"Book of Abstracts" 2011 of the Conference

Transcription

CONFERENCE ABSTRACTS
International Student Conference
“Science and Progress”
German-Russian
Interdisciplinary
Science Center
St. Petersburg – Peterhof
November, 14-18
2011
Programm
International Student Conference
“Science and Progress”
November, 14-18
St. Petersburg – Peterhof
November, 14 (Monday)
• 09.30 – 10.30
Registration (hall, 1-st floor, Faculty of Physics)
• 10.30 – 10.45
Opening Ceremony, aud. B-04
• 10.45 – 11.25
Lection I, aud. B-04
“Analysis and control of photon-induced processes”,
Prof. Dr. Eckard Ruehl, Faculty of Chemistry, Freie University Berlin,
Germany
• 11.30 – 12.10
Lection II, aud. B-04
“Topological surface states by spin-resolved photoemission”,
Prof. Dr. Oliver Rader, Helmholtz-Zentrum Berlin, Germany
• 12.10 – 12.40
Coffee-break
• 12.40 – 14.00
Oral sections
E – Applied Physics, aud. B-02
G – Theoretical, Mathematical and Computational Physics, part I,
aud. B-04
H – Biophysics, part I, aud. 210
Steering Committee of G-RISC (for SC members only, Office G-RISC)
• 14.00 – 15.00
Lunch
• 15.00 – 16.30
Oral sections
G – Theoretical, Mathematical and Computational Physics, part II,
aud. B-04
H – Biophysics, part II, aud. 210
Poster section, 2-nd floor hall
E – Applied Physics
3
• 16.30 – 17.00
Coffee-break
• 17.00 – 18.00
Oral Section
G – Theoretical, Mathematical and Computational Physics, part III,
aud. B-04
Poster Section, 2-nd floor hall
H – Biophysics
• 18.00 – 19.00
Supper
• 19.00 – 20.30
G – Theoretical, Mathematical and Computational Physics
November, 15 (Thursday)
• 10.30 – 12.00
Annual Metting of G-RISC “Results-2011”, aud. B-04
• 12.00 – 12.30
Coffee-break
• 12.30 – 13.15
Lection III, aud. B-02
“Atom dynamics on reconstructed silicon surfaces”,
Prof. Dr. Alexander Saranin, Institute of Automation and Control Prosesses
FEB RAS, Vladivostok, Russia
• 13.15 – 14.00
Lunch
• 14.00 – 18.00
Excursion to Pavlovsk (bus starts from Faculty of Physics)
18.00 – 19.00
Supper
November, 16 (Wednesday)
• 10.30 – 12.00
Oral sections
B – Geo- and Astrophysics, part I, aud. B-02
F – Optics and Spectroscopy, part I, aud. 210t
• 12.00 – 12.30
Coffee-break
12.30 – 14.00
Oral section
B – Geo- and Astrophysics, part II, aud. B-02
F – Optics and Spectroscopy, part II, aud. 210
4
• 12.30 – 13.15
Lection IV, aud. B-04
“Plasma technology – an overview. Plasma research at the INP
Greifswald”,
Prof. Dr. Dirk Urlandt, Leibniz Institute for Plasma Science and Technology,
Greifswald, Germany
• 13.15 – 14.00
Lection V, aud. B-04
“Solid state NMR spectroscopy and application to study properties of nanosized systems”
Prof. Dr. Dieter Michel, Leipzig University, Germany
• 14.00 – 15.00
Lunch
• 15.00 – 16.30
Oral sections
A – Chemistry, aud. B-04
I – Resonance Phenomena in Condensed Matter, aud. B-02
Poster section, 2-nd floor hall
B – Geo- and Astrophysics
• 16.30 – 16.50
Coffee-break
• 16.50 – 18.00
Poster sections, 2-nd floor hall
A – Chemistry
F – Optics and Spectroscopy
I – Resonance Phenomena in Condensed Matter
18.00 – 19.00
Supper
November, 17 (Thursday)
• 10.30 – 12.00 Oral section
D – Solid State Physics, part I, aud. B-04
• 11.15 – 12.00
Lection VI, aud. B-02
“Applications of non-thermal atmospheric pressure plasmas. Diagnostics and
simulation of atmospheric pressure plasmas”,
Prof. Dr. Dirk Urlandt, Leibniz Institute for Plasma Science and Technology,
Greifswald, Germany
• 12.00 – 12.30
Coffee-break
• 12.30 – 14.00
Oral sections
C – Mathematics and Mechanics, part I, aud. B-02
5
D – Solid State Physics, part II, aud. B-04
• 14.00 – 15.00
Lunch
• 15.00 – 16.30
Oral section
C – Mathematics and Mechanics, part II, aud. B-02
D – Solid State Physics
• 16.30 – 16.50
Coffee-break
• 16.50 – 18.00
C – Mathematics and Mechanics, part III aud. B-02
• 18.00 – 18.30
C – Mathematics and Mechanics
• 18.00 – 19.00
Supper
November, 18 (Friday)
• 12.50 – 13.20
Ceremony of Ending, Honor Price, aud. B-04
• 13.20 – 15.00
Lunch
• 15.00 – 18.00
Excursion to Oranienbaum – Menshikov’s Palas, park
(bus starts from Faculty of Physics)
6
Organizing committee
Prof. Dr. S.F. Bureiko, Prof. Dr. A.M. Shikin, E.I. Spirin,
E.V. Serova, Dr. A.G. Rybkin, A.A. Popova, Dean of Physical Faculty of SPbSU
Coordinator of G-RISC in SPbSU
Dean-assistant of Physical Faculty of SPbSU
Head of Academic Mobility Department
G-RISC office in SPbSU
G-RISC office in SPbSU
Program Committee
Prof. Dr. E. Rühl, Prof. Dr. C. Laubschat, Prof. Dr. A.M. Shikin, Prof. Dr. Yu.S. Tver’yanovich, Prof. Dr. V.N. Troyan, Coordinator of G-RISC in FU Berlin
Physical Faculty of TU Dresden
Coordinator of G-RISC in SPbSU
Chemical Faculty of SPbSU
Physical Faculty of SPbSU
Heads of sections
A. Chemistry – Prof. Dr. Yu.S. Tver’yanovich, Chemical Faculty of SPbSU
B. Geo- and Astrophysics – Prof. Dr. V.N. Troyan, Physical Faculty of SPbSU,
Dr. V.G. Nagnibeda, Mathematical and Mechanics Faculty of SPbSU
C. Mathematics and Mechanics
– Prof. Dr. V. Reitmann,
Mathematical and Mechanics Faculty of SPbSU
D. Solid State Physics – Prof. Dr. A.P. Baraban,
E. Applied Physics
– Prof. Dr. A.S. Chirtsov,
F. Optics and Spectroscopy
G. Theoretical, Mathematical and Computational Physics
– Prof. Dr. Yu.V. Chizhov,
Prof. Dr. N.A. Timofeev,
– Prof. Dr. Yu.M. Pis’mak,
7
H. Biophysics
– Prof. Dr. N.V. Tsvetkov,
I. Resonance Phenomena in Condenced Matter
– Prof. Dr. V.I. Chizhik,
Contacts
Physical Faculty of Saint-Petersburg State University
Ulyanovskaya ul. 3,
Peterhof, St. Petersburg, Russia
198504
Tel. +7 (812) 428-46-56,
Fax. +7 (812) 428-46-55
E-mail: [email protected]
Website: www.phys.spbu.ru/grisc
8
Invited Lections
German-Russian Interdisciplinary Science Center
(G-RISC)
Prof. Eckart Rühl, Natalia Kolanovska
[email protected]
Physical Chemistry, Freie Universität Berlin
The German-Russian Interdisciplinary Science Center (G-RISC) was founded
as a binational platform of scientific research and education with two main offices at
Saint-Petersburg State University, Russia and Freie Universität Berlin, Germany.
The Center of Excellence was established in March 2010. It builds on a
long-standing tradition of scientific cooperation between scientists of Russia and
Germany. G-RISC relies on funding and regulations of the German Academic
Exchange Service (DAAD) and the German Federal Foreign Office. The Center
supports education and research in binational projects between both countries. Focus
is interdisciplinary research in four fields of natural sciences: physics, geophysics,
physical chemistry, and mathematics.
G-RISC is operated by two scientific coordinators: Prof. Alexander Shikin
(Saint-Petersburg State University) and Prof. Eckart Rühl (Freie Universität Berlin),
supported by administrative coordinators and binational Steering Committee.
G-RISC encourages the experienced and novel promising groups to submit
their projects. Proposals can be submitted by all research institutions in Russia and
Germany and are selected by Steering Committee on the basis of there scientific
quality. This type of competition is organized every six months. In January 2012
starts the fifth funding period.
G-RISC funds primarily mobility of young researchers between Russia and
Germany. This concerns first of all research stays in laboratories of the partner
groups in the other country. For outstandingly bright Russian students who are
involved in interdisciplinary research projects with German partner groups it is also
possible to become a sur-place stipend for maximum half a year. It is anticipated
that research stays and stipend are increasing the chances for stable long-term
Russian-German collaborations. Each single project is important helping to tie
researchers and research interests together and to develop novel, interdisciplinary
research between Russia and Germany.
In total, more than 30 institutions and more than 100 young and experienced
researchers from Russia and Germany conduct research and teach at the Center.
Since the opening of G-RISC five interdisciplinary workshops/conferences with
over 400 participants have been already held. Detailed information can be found
at the website: http://www.g-risc.org.
Current developments and future perspectives of G-RISC will be presented
and all open questions related to G-RISC will be answered.
10
Topological surface states by spin-resolved
photoemission
Prof. Oliver Rader
rader@helmholtz-berlin.,de
Helmholtz-Zentrum Berlin für Materialien und Energie
The topological insulator was proposed in 2005 when Kane and Mele theoretically
investigated its two-dimensional version, the quantum spin Hall insulator, taking graphene as example: Provided a sizeable spin-orbit interaction existed in that material, a
corresponding electronic band gap opens giving rise to topological surface states which
are 100% spin polarized and protected by time-reversal symmetry. We will introduce
the underlying concepts of this effect which has for the first time been proven in 2007
by transport experiments in HgTe quantum wells at Würzburg University.
In the experimental part of this presentation we will show for graphene how
the weak spin-orbit interaction in this material can indeed be enhanced by 4 orders
of magnitude to 100 meV splitting but we argue that it is principally impossible
to realize the quantum spin Hall insulator in this material. --- The systems Bi2Te3
and Bi2Se3 are instead three-dimensional topological insulators where the topologically protected state is a two-dimensional surface state. We investigate this
system by spin- and angle-resolved photoemission and discuss the observed high
spin polarization of the topological surface state and of bulk states in the context
of frequent attempts to measure their signatures in transport experiments. --- Metal
surfaces are known to host electronic states with a Rashba-type spin-orbit splitting.
We observe such a state on iridium with an extremely large splitting. Surprisingly,
this state continues to exist after graphene is catalytically deposited on top, and
indications are presented that a topological protection could be responsible for this
stability. --- Magnetic fields break time-reversal symmetry and lift the protection
of the surface state. We show for Bi2Te3 and Bi2Se3 that topological surface states
are surprisingly tolerant to deposited magnetic moments at the surface which can
be used for various device applications.
References
1. D. Marchenko, A. Varykhalov, M. R. Scholz, E. I. Rashba, G. Bihlmayer, A.
Rybkin, A. M. Shikin, O. Rader. Giant Rashba splitting, band topology and hybridization at the graphene-Au interface, submitted to Nat. Mater.
2. A. Varykhalov, D. Marchenko, M. R. Scholz, E. D. L. Rienks, T. K. Kim, G.
Bihlmayer, J. Sánchez-Barriga, O. Rader, arXiv:1104.3308
3. M. R. Scholz, D. Marchenko, A. Varykhalov, A. Volykhov, L. V. Yashina, and
O. Rader. High spin polarization and circular dichroism of topological surface
states on Bi2Te3, arXiv:1108.1053
4. M. R. Scholz, J. Sánchez-Barriga, D. Marchenko, A. Varykhalov, A. Volykhov,
L. V. Yashina, and O. Rader. Tolerance of topological surface states towards magnetic moments: Fe on Bi2Te3 and Bi2Se3, arXiv:1108.1037
11
Atom Dynamics on Reconstructed Silicon Surfaces
Prof. Alexander A. Saranin
[email protected]
Institute for Automation and Control Processes FEB RAS,
Vladivistok, Russia
Study of atoms dynamics on surfaces plays an important role in the understanding of the mechanisms of low-dimensional structures formation. In the present
work we investigated a number of metal-induced reconstructions on Si surface
by using high-resolution scanning tunneling microscopy in which atom dynamic
plays an essential role.
(1) We demonstrated the possibility of doping of atomic magic cluster in In/
Si(100)4×3 system [1] and its switching behavior [2].
(2) It was found that In atom adsorption results in the domain wall melting in
Si(111)α-√3×√3-Au system [3].
(3) Ge atom migration on the incommensurate Si(111)'5×5'-Cu surface was
investigated [4].
(4) The even-odd symmetry is broken in the self selection of distances between
indium magic-number clusters on a Si(100)4×3-In reconstructed surface. Cluster
pairs separated by even units are less abundant because they are linked by silicon
atomic chains carrying topological solitons, which induce local strain and create
localized electronic states with higher energy [5].
1.
2.
3.
4.
References
V. G. Kotlyar et al. //Phys. Rev. Lett. 91 (2003) 026104.
A. A. Saranin et al. //Phys. Rev. B. 74 (2006) 125304.
D. V. Gruznev et al. //Phys. Rev. B. 73 (2006) 115335.
D. V. Gruznev et al. //Surf. Sci. 604 (2010) 666.
5. [5] M. Y. Lai et al., //Phys. Rev. Lett. 106, 166101 (2011).
12
Presentations St. Petersburg State University
Lectures mainly for students
Prof. h.c. Dirk Uhrlandt
Leibniz-Institute for Plasma Science and Technology e.V. (INP
Greifswald), Germany
16.11.
A)
Plasma
Technology
–
an
Overview
(from basic operation of a plasma, features like radiation, plasma volume processes
and interaction with surfaces to the main application ranges like radiation sources,
conversion of substances, surface treatment)
B) Plasma Research at the INP Greifswald
(includes topics and recent highlights of the research at the INP Greifswald, short
presentation of two other institutes dealing with plasma physics in Greifswald,
some facts of the Greifswald university, features of the town Greifswald and its
surrounding at the Baltic sea coast, conditions for students education)
17.11.
C) Applications of Non-Thermal Atmospheric Pressure Plasmas
(includes different kinds of these plasmas and their features, established applications e.g. for gas conversion as well as potentials for new applications e.g. in
environmental techniques, biology and medicine)
D) Diagnostics and Simulation of Atmospheric Pressure Plasmas
(focus on optical and spectroscopic methods as well as models of the electron kinetics and the plasma chemistry, fluid simulation of the discharge development)
13
Solid state NMR spectroscopy and application to study
properties of nanosized systems
Prof. Dieter Michel
[email protected]
Department of Experimental Physics II, Leipzig University,
Linnestrasse 5, 04103 Leipzig, Germany
In the first part of the lecture a more general introduction into possibilities and
limitations of solid state NMR spectroscopy will be given, including the techniques
of solid-state high-resolution NMR mainly for nuclei with nuclear quadrupole
moments. This part is not considered to be a representative presentation but only
a simplified overview.
In the second part NMR spectroscopy (also with a reference to the application
of electron paramagnetic resonance, EPR) is used to study size effects on the properties of small particles of materials showing ferroelectric properties in the bulk
phase. Besides barium titanate and lead titanate [1-3] the studies are extended to
the behaviour of NaNO2 and other materials embedded into mesoporous materials.
As composite materials mesoporous silicates of type MCM 41 and synthetic opals
will be used [4]. It will be shown that NMR and EPR [5] and NMR methods can
sensitively probe the spontaneous ferroelectric polarization and are suitable to study
size dependent changes of ferroelectric properties. This is based on the fact that
the quadrupole coupling constant CQ = e2qQ/h (in case NMR studies using nuclei
with quantum number I > ½) as well as the fine structure parameter D (in case of
EPR studies) are proportional to the square of the spontaneous polarization. The
advantage of the NMR studies is that they may be performed on natural probes
without dotation, e.g. on 23Na, 137Ba nuclear spins. Central transitions (mI = -1/2 ⇔
mI = +1/2) NMR spectra are measured the line shape of which is dominated by the
nuclear quadrupole interaction in second order of the perturbation theory. This was
checked by measurements at various Larmor frequencies. The quadrupole coupling
constant CQ can be directly determined from the NMR line shape of the central
transition line where the distance between the two edge singularities (e.g. in the
tetragonal phase of barium titanate) is given by the coupling constant. Normally
the studies show that the small particles reveal two different regions reflecting a
normal (“ordered”) part an a distorted part (“disordered” part). On this base, details
about critical sizes and size driven phase transitions may be investigated.
References
1. Sedykh P., Haase J., Michel D., Charnaya E.V. // Ferroelectrics 363 (2008)
215-226.
2. Sedykh P., Michel D. // Phys. Rev. B 79, (2009) from 134119-1 to 134119-8.
3. Sedykh P., Michel D., Charnaya E.V., Haase J. // Ferroelectrics, 400 (2010)
135-143.
14
4. Cheng Tien, Charnaya E.V., Lee M.K., Baryshnikov S.V., Michel D., and
Böhlmann W. // Ferroelectrics, 366 (2008) 177-186. See also further refs. of
Charnaya E.V. et al. cited in this paper.
5. Erdem E., Boettcher R., Glaesel H.-J., Hartmann E., Klotzsche G., Michel D.,
in: Advances in Solid State Physics, edited by B. Kramer, Springer-Verlag, Berlin/
Heidelberg, 2005, p. 351.
15
A. Chemistry
Quantum-chemical investigation of 2,1-benzisoxasoles
formation process
Andreeva Ksenia
[email protected]
Scientific supervisor: Prof. Orlov V.Yu., Department of Organic
and Biologic Chemistry, Faculty of Biology and Ecology, Yaroslavl
Demidov State University
Reactions of aromatic nucleophilic hydrogen substitution (SNArH) is one of
perspective methods for nitroaromatic compounds functionalization. The arylacetonitriles with nitroarenes interaction processes is one of the examples of nucleophilic hydrogen substitution reaction. The final product of such type reactions is
2,1 - benzisoxazole.
CN
CH2
Ar
H2O
NO2
OH-
CN
+ CHAr
X
H-OR
-
O O
N+
X
-
CN
CH Ar
H
RO-
H-OR
-
O OH
N
CN
C Ar
H
X
RO-
-
-H2O
+H2O
-
O
N
OR
N O
Ar
CN
Ar
-
X
-CN
ROH
X
1 X=Cl; 2 X=Br; 3 X=Ph; 4 X=OPh; 5 X=СН(ОСН2СН2О)2;
6 X=С(ОСН2СН2О)2СН3;7 X=COOH; 8 X=C6H4CH(OCH2OCH2);
In this work, the quantum chemical modeling has been carried out, and
potential energy surface (PES) profiles has been obtained for cyclization stage
(2,1-benzisoxazolic cycle formation process) of arylacetonitriles with nitroarenes
interaction. The modeling has been performed for various para-substituted nitrobenzenes (1-8).
The values of activation energy barriers (ΔЕakt) have been obtained, during
quantum-chemical modeling. Also, the experimental data for kinetic regularities
of investigated process – the values of efficient velocity constants – has been
obtained with the influence of 1-8 substratum structure. The ln kef dependence of
ΔЕakt values has been obtained. It was shown, that the character of this dependence
is linear, and the correlation coefficient is 0,992.
It is established, that correlation of modeling results, which obtained during
the quantum-chemical modeling in this work, has a good correspondence with the
results, obtained during the experiment. The analysis of obtained results has been
shown, that 2,1-benzisoxasolic cycle formation stage for arylacetonitriles with
nitroarenes interaction process is limiting stage, and this stage defines the specific
characteristics of investigated process.
18
Study on polyamide/montmorillonite membranes for
pervaporation of methanol-toluene mixture
Avagimova Natalia
[email protected]
Scientific supervisors: Dr. Polotskaya G.A., Prof. Toikka A.M.
Department of Chemical Thermodynamics and Kinetics, Faculty
of Chemistry, Saint-Petersburg State University; Institute of
Macromolecular Compounds, Russian Academy of Sciences,
Saint-Petersburg, Russia
Development of membranes with new properties by modification of polymers
by inorganic particles is one of the most promising ways for progress in membrane
technology. Introduction of inorganic additives in polymer matrices could influence
on permeability and selectivity of polymer materials. The objectives of this work
are poly(phenyleneisophtalamide) (PA) and montmorillonite (MMT). PA is a commercially available and exceptionally interesting in membrane application because
of its good mechanical, thermal and chemical resistance. Montmorillonite Cloisite®
15A is a natural nanoadditive modified with a quaternary ammonium salt.
The aim of the present work is to prepare PA/MMT membranes and to study
their sorption and transport properties in pervaporation of methanol/toluene mixture. The PA/MMT membranes (dense films of 25–35 μm thick) containing up to
7 wt% MMT were prepared by dispersion ММТ and PA in solid-phase method
with subsequent dissolution in dimethylacetamide (DMA) and sonation. After that
solution is applied thinly on a glass substrate and dried. Pervaporation of methanol/
toluene mixture was studied in wide range of feed mixture contents at 50°С in
vacuum conditions. In pervaporation the mass transfer through membrane occurs
by three-stage process: sorption of penetrant on membrane surface, diffusion
through the membrane and desorption on the back side of membrane. Sorption
coefficient and effective diffusion coefficient were evaluated from data of sorption experiments that were carried out by an immersion of membrane samples in
individual liquid components of feed. The sorption kinetics curves were plotted
and analyzed. The values of diffusion coefficients were determined from the slop
of sorption curves at the initial time.
Membranes based on PA/MMT composites were selective with respect to methanol in pervaporation of organic mixtures. It was established that PA/MMT(3wt%)
membrane exhibits maximal permeability and selectivity in separation of methanol/
toluene mixture.
This work was supported by Russian Foundation for Basic Research (grant №
09-03-00812). The authors acknowledge Saint-Petersburg State University for a
research grant (reg. № 12.0.105.2010 (01201052803)).
19
Dependence of rheological properties of supramolecular
system based on L-cysteine and silver ions on its structure
Baranova Olga
[email protected]
Scientific supervisor: Dr. Pakhomov P.M., Department of
Physical Chemistry, Faculty of Chemical Technology, Tver State
University
The study of supramolecular systems is one of the most important trends of
modern chemistry. Nowadays, the wide variety of such supramolecular ensembles
including polymers is analyzed. One of these systems is supramolecular gel
obtained from water solution of L-cysteine and silver nitrate [1]. Gel has some
unique properties. Ability to gel formation with very low concentrations of dissolve
components (less 0, 1%) and within very narrow concentration and temperature
range is one of most interesting properties. The structural distinctive features of
CSS condition such a behavior [2].
The aim of this research was further study structure and properties of cysteinesilver solution (CSS) and hydrogel based on it using dynamic light scattering
(DLS) method and viscometry, as well as establishment dependence of rheological
properties of CSS and gel on their structure.
It was established that the average hydrodynamic radius (rH) of scattering particles is a convenient parameter for CSS structure characterization. At the same
time, it is impossible to use particles size distribution as such parameter as it is too
unstable in time in our case while the rH stays constant a quite time.
Rheological experiments achieved that CSS has abnormal reduced viscosity
during the dilution (growth of viscosity at low concentrations). In the first the reduced viscosity and the average hydrodynamic radius of particles in CSS smoothly
decrease at the dilution of CSS up to dissolved phase concentration equal 0,05%.
It indicates that from the beginning the weak, not covalent bonds between clusters
(particles) in CSS are destroyed. At the further dilution, the viscosity and rH was
increased. It is known, that fractal clusters in CSS composed of supramolecular
chains of silver mercaptide [1, 3] are situated in a «clue» form in solution. It was
indicated by the viscosity and rH increasing at the strong dilution. At low concentrations of dissolved components, the supramolecular «clues» become looser, frictional
force between particles rises and because of this the CSS viscosity increases too.
In addition, it was established that with the rise in temperature (to 40-45°C),
the supramolecules destruction takes place and/or size of solvation sphere decreases.
References
1. Pakhomov P.M. et al.// Kolloidnyi zhurnal. V. 66. N 1. P. 75-79 (2004).
2. Pakhomov P.M. et al.// Polymer Science. V. 53. N. 9. P. 1574-1581 (2011).
3. Komarov P.V. et al.// Kolloidnyi zhurnal. V. 73. N 4. P.470-482 (2011).
20
New associates of imino- and hydroxyimino-Pt(II and
IV) complexes with 18-crown-6
Bulatov E.Yu.1, Chulkova T.G.1, Gushchin P.V.1, Haukka M.2,
Kukushkin V.Yu.1
[email protected]
Scientific supervisor: Dr. Chulkova T.G., Faculty of Chemistry,
Saint Petersburg State University
1
2
Department of Chemistry, SPbSU, St.Petersburg, Russian Federation;
Department of Chemistry, University of Eastern Finland, Joensuu, Finland
Association of heteroatom containing macrocyclic compounds such as crown
ethers with metal complexes provides a new approach for generation of supramolecular architecture [1]. A large amount of crown ether associates have been produced and studied by different methods [2]. In this study, a new type of 18-crown-6
associates with platinum complexes has been produced using trans-[PtClnL2]
(n = 2, 4; L = acetaldoxime, acetoxime, methyl propionimidate) as representative
platinum complexes. The associates were characterized by X-ray crystallography,
IR spectroscopy, and elemental analysis.
Fig. 1. trans-[PtCl2(methyl propionimidate)2]/18-crown-6 associate packing in
solid state.
The structural features of the trans-[PtClnL2]/18-crown-6 associates, the nature
of interactions between the ligands and 18-crown-6 molecules, structural changes
in the platinum complexes and the crown ether due to their assembly into supramolecular associates will be discussed.
The authors are very much obliged to Russian Fund for Basic Research for grant 0903-00065-а and Saint-Petersburg State University for a research grant (2011-2013).
References
1. Batinic-Haberle I., Crumbliss A.L. // Inorg. Chem., 1995, 34, 928-932.
2. Colquhoun H.M., Lewis D.F., Stoddart J.F., Williams D.J. // J. Chem. Soc.,
Dalton Trans., 1983, 607-613; T.B. Vance, Jr., E.M. Holt, D.L. Varie, S.L. Holt.
Acta Crystallogr., Sect. B, 1980, 36, 153-155; T.G. Chulkova, P.V. Gushchin, M.
Haukka, V.Yu. Kukushkin. Inorg. Chem. Commun., 2010, 13, 580-583.
21
Thermal decomposition of РН2ВН2•NMe3
Butlak Alina, Kazakov Igor
[email protected], [email protected]
Scientific supervisor: Dr. Timoshkin A.Y., Department of Inorganic
Chemistry, Saint-Petersburg State University
РН2ВН2•NMe3 is a colorless viscous liquid slowly decomposing at room temperature. Knowledge about its thermal decomposition is important due to suggested
use of phosphinoboranes as hydrogen storage materials [1].
Decomposition processes were experimentally investigated by static tenzimetry
method with glass membrane null-manometer [2]. РН2ВН2•NMe3 was purified by
slow vacuum sublimation below the melting point and stored frozen in the fridge
in sealed glass systems. Measured amount of sample was placed in the system of
known volume, vapor pressure – temperature dependence measurements have
been performed in the range 25-300 ºC. At several temperatures, system was
thermostated and kinetic measurements have been performed. By repetition of
the heating-cooling cycles information about reversibility/irreversibility of the
process of thermal decomposition was obtained, freezing the system by liquid
nitrogen allowed to qualitatively analyze the amounts of gaseous products evolved
at different temperatures.
Major results can be summarized as follows: at low temperatures (up to 150 ̊ C)
РН2ВН2•NMe3 slowly releases trimethylamine as the only gaseous product.
Formation of non-volatile (H2BPH2)n polymer in the condensed phase was proposed.
Above 150 ºC release of H2 and PH3 was observed which is accompanied by the
formation of volatile adduct BH3NMe3 (isolated and structurally characterized) and
non-volatile glassy polymer (HxBPHx)n, x <2. Further release of hydrogen gas from
this polymer occurs at higher temperatures (ca 300 ºC). Slow hydrogen evolution
and formation of side products do not allow to recommend the title compound for
the practical applications. It is suggested that replacement of NMe3 by non-volatile
ligand may improve the situation.
This work was supported by Saint Petersburg State University research grant
12.37.139.2011. We are thankful to Professor Manfred Scheer (University of
Regensburg, Germany) for providing РН2ВН2•NMe3 samples.
References
1. Staubitz A., Robertson A.P.M., Sloan M. E., Manners I. // Chem. Rev., 2010,
110 (7), pp 4023–4078.
2. Suvorov А.V. Thermodynamic chemistry of vapor phase, Leningrad, 1970.
-208 p. (in Russian).
22
Hydrated forms of lithium and sodium perchlorate in
aqueous solutions by IR spectroscopy
Davidian Anna
[email protected]
Scientific supervisor: Dr. Khripun M.K., Department of Inorganic
Chemistry, Faculty of Chemistry, Saint-Petersburg State
University
The aim is to study the conversion of hydrate forms of lithium and sodium
perchlorate at varying concentrations in solution.
The IR absorption spectra of the first overtone of stretching vibrations of
water νOH (5400 - 7500 cm-1) were measured, depending on the concentration of
aqueous solutions of LiClO4 and NaClO4 in the range 0 - 4.20 M and 0 - 8.16 M,
respectively. The spectra were recorded on a Spectrum BX spectrometer in steps
of 2 cm-1 at room temperature (21°C). The test solution was placed in a glass cell
with a layer thickness of 0.1 cm.
It was found that variation of the concentration of selected alkali metal perchlorates determines changing shape of the contour ν02OH (H2O). If you change the
spectra of a solution of lithium perchlorate, isosbestic point will be observed. In
solutions of sodium perchlorate is not.
The variance of the experimental optical density was deternined for the two
systems at each measured wavelength. To determine the variance of the optical
density was prepared in two series of solutions LiClO4 and NaClO4. Each series
contained ten different concentrations, and recorded three times.
Chemometric analysis of the experimental data matrix Aexp (Np, Nw) was done,
where Np - number of experimental points, Nw - number of spectral channels. These
data were used to establish the number of factors which determine the dispersion
of the observed property.
The spectra of forms and abstract diagrams of distribution of these forms of
concentrations were obtained by the method of "soft" modeling.
Chemometric analysis in combination with a phenomenological model of the
structure of aqueous electrolyte solutions shows that the change of the spectra in
the case of solutions of lithium perchlorate can be interpreted as the antibate change
of water not related to ions and water in the structure of lithium hydrate. In the
case of sodium perchlorate, these changes are associated with the interconversion
of forms hydrates of sodium also.
23
Tensimetric investigation of complex formation between
alumazene and acetonitrile
. Doinikov Dmitry
[email protected]
Scientific supervisor: Dr. Timoshkin A.Y., Department of
Inorganic Chemistry, Faculty of Chemistry, Saint-Petersburg
State University
Alumazene (Az), as shown in Fig. 1, is a borazine-like 13-15 group compound
with alternating Al –N atoms in the ring. Due to more polar character of the Al–N
bond compared to the B–N bond in borazine, alumazene is less “aromatic” and
is able to form complexes with Lewis bases, such as pyridine (py). Az(py) and
Az(py)2 can be isolated; Az(py)3 only exists in excess of pyridine [1]. Acetonitrile
(an), being a weaker donor, is expected to be less reactive.
iPr
N
iPr
H 3C
Al
iPr
CH3
Al
N
iPr
N
iPr
Al
CH 3
iPr
Fig. 2. Vapour pressure-temperature deFig. 1. Alumazene.
pendence scheme.
In the present work, two experiments with Az:an ratio of 1:6.7 and 1:3.8 were
performed. Vapor pressure-temperature dependence was measured by a static tensimetric method with glass membrane null-manometer [2]. It is found that in excess
of acetonitrile alumazene forms solid adducts Az(an)x (3.7<x<5.4). After heating to
340~350K the loss of acetonitrile is observed (area a in Fig. 2). The estimated enthalpy
of the process (4.8~8.0 kJ/mol) is too small to be related with a dissociation of a donoracceptor bond. Therefore, excess of an is physically bound in the crystalline structure
of the complex. The further heating to 370~380K (area b) shows the elimination of
a coordinated an (∆H=77±2 kJ/mol) with formation of solid Az(an)x (1.8<x<2.4).
After the system is heated to 430K, the pressure dramatically drops (point c). We
attribute this fact to polymerization of acetonitrile, catalyzed by alumazene.
This work was supported by Saint Petersburg State University research grant
12.37.139.2011. We are thankful to Professor Jiri Pinkas (Masaryk University,
Brno, Czech Republic) for providing alumazene samples.
References
1. Löbl J., Timoshkin A.Y., Cong T., Necas M., Roesky H.W., Pinkas J. // Inorg.
Chem., 46, p. 5678-5685, (2007).
2. Davydova E.I., Sevastianova T.N., Suvorov A.V., Timoshkin A.Y. // Coord.
Chem. Rev., 254,p. 2031-2077, (2010).
24
Synthesis of potential inhibitors of Estrone Sulfatase
Drozdov Andrey
[email protected]
Scientific supevisor: Prof. Shavva A.G., Department of Natural
Product Chemistry, Faculty of Chemistry, Saint-Petersburg State
University
Breast cancer is the most common cancer diagnosed in women. Up to 95%
of human breast cancers, at the origin, are hormone-dependent. One of the main
purposes of endocrine therapy is to reduce this hormonal stimulation of tumor cell
proliferation by either inhibiting receptor activation (anti-estrogens) or inhibiting
the formation of E2 using specific anti-enzymes which are involved in tissulal E2
biosynthesis. One of the most perspective way to block biosynthesis is inhibition
of steroid sulfatase (ES). Estrone 3-sulfamate (EMATE) was the first potent ES
inhibitor that causes irreversible inactivation of the enzyme. However, in vivo it
can be hydrolyzed to estone, active estrogen, thus rendering EMATE unsuitable
for usage in the treatment of breast cancer. Potential ES inhibitors should be based
on the compounds without estrogenic properties [1-3].
We have synthesized several sulfamate derivatives of 8α- analogues of steroid
estrogens. These compounds are being tested for ability to inhibit ES.
O
S
O
H
H
O
H2N
O
I
S
O
H
O
H
O
S
O
O
H
O
II
O
S NH2
O
O
H
H
H
IV
O
H2N
H
O
O
H2N
H
H
H
H2N
O
O
O
O
S
O
H
III
O
NH2
O S
O
O
H
V
O
(CH2)n
H
H2N S O
O
H
O
H
H
n = 1,2
O
Fig. 1. Potential inhibitors of Estrone Sulfatase.
VI, VII
References
1. Lawrence H., Vicker N., Allan G.M., Smith A., Mahon M.F., Tutill H.J., Purohit
A., Reed M.J., and Potter B.V.L. // J. Med. Chem., 48, 2759 (2005).
2. Numazawa M., Ando M., Watari Y., Tominaga T., Hayata Y., Yoshimura A. //
J. Steroid Biochem. Mol. Biol., 96, 51, (2005).
3. Prokai-Tatrai K., Perjesi P., Rivera-Portalatin N.M., Simpkins J.W., Prokai L.
// Steroids, 10, 33-42. (2007).
25
Unusual Rh(II)-catalyzed reactions of diazoesters
with α,β-unsaturated δ-(N-aryl)aminoesters: tandem
N-H-insertion/intramolecular cyclization into N-aryl
pyrrolidines
Galkina Olesya
[email protected]
Scientific supervisors: Prof. Dr. Nikolaev V.A., Department of
Organic Chemistry, Faculty of Chemistry, Saint-Petersburg State
University; Prof. Dr. Schneider Ch., Institut für Organische
Chemie, Universität Leipzig
Pyrrolidine unit is an important heterocyclic element found in the structure of
natural alkaloids and various pharmaceutically active substances which show a wide
range of biological activity [1]. Numerous methods for the synthesis of pyrrolidines
are described in the literature, however application of a catalytic decomposition of
diazo compounds for this purpose is practically unknown [2].
We for the first time established that catalytic decomposition of diazocarbonyl
compounds 1 with rhodium(II) tetraacetate in the presence of esters of N-aryl
substituted α-unsaturated δ-amino acids 2 [3] results in the formation of N-aryl
pyrrolidines 3 with good yields (up to 86%).
R
N2
Ar
+
R1
O
1
N
H
Rh(II)
CO2Et
Ph
Ar
-N2
R
H
N
Ph
2
Ar
R1
O
Ph
N
O
R1
R
CO2 Et
EtO2 C
3
4
R, R1 = H, OAlk; CO2Alk, OAlk; COMe, Me; CO 2-CMe 2-O etc.
The reaction presumably occurs as a tandem process that involves the initial
insertion of Rh(II)-carbenoid into the N-H bond of the amino group of unsaturated
ester 2 and subsequent intramolecular cyclization of tertiary amines 4 formed into
pyrrolidines 3. In some cases intermediate N-H insertion products 4 can be isolated
from reaction mixture.
The reaction usually gives rise to the formation of two diastereomeric pyrrolidines 3. It was established that cis-trans-stereoselectivity and efficiency of the
catalytic process essentially depends on the structure of the diazocarbonyl substrate
used, temperature and other reaction conditions.
References
1. O’Hagan D.// Nat. Prod. Rep., v. 17, p. 435 (2000), and references cited
therein.
2. Zhu Y., Zhai C., Yue Y., Yang L., Hu W. // Chem. Commun., p. 1362 (2009).
3. Sickert M., Schneider Ch. // Angew. Chem. Int. Ed., v. 47, p. 3631 (2008).
26
Some experimental peculiarities of behavior of
multicomponent reactive systems: solubility and critical
phenomena
Golikova Alexandra, Trofimova Maya, Toikka Maria
[email protected]@yandex.ru, maya.
[email protected]
Scientific supervisor: Dr. Toikka M.A., Department of Chemical
thermodynamics and kinetics, Faculty of Chemistry, SaintPetersburg State University
Phase transitions accompanied by chemical reactions are of great importance
as effective and energy saving industrial processes. The data on such coupled
processes can be used both for reaction engineering and separation technology
purposes. Liquid phase splitting and critical states of liquid – liquid equilibrium
could also significantly influence on the reaction kinetics [1].
The main goal of this work is to discuss some experimental peculiarities of
quaternary reactive systems on example of the system with ethyl acetate synthesis
reaction. The acetic acid – ethanol – water – ethyl acetate system is one of the limit
set of reacting system with almost full set of experimental data on binary and ternary
subsystems including both chemically equilibrium and non-equilibrium states.
The experimental part of work includes: the purifying of substances, the getting of solubility data and in the end – the concerning of critical phenomena in
this system. To purify the substances the purifying columns were used. Some new
solubility data were determined with the use of special thermostat constructed
(with transparent walls) for the ternary subsystems (ethanol – water – ethyl acetate,
acetic acid – water – ethyl acetate) and for quaternary system investigated. One
of the main aspects of the study of solubility is the determination of critical points
and critical manifolds (curves, surfaces). In the case of binary systems, the critical
states usually are considered as a critical (plait) point for diagrams “composition–
temperature (or pressure)”. For ternary phase diagrams at variable temperature, the
critical curve can be considered. In general, the critical curves are sets of critical
points resulting from shifts of external conditions (e.g., temperature changes). Some
recent experimental data on critical curves disposition had been presented in [2,
3]. In the case of quaternary LLE, the critical curve may be realized at isothermal–
isobaric conditions. Such a critical curve in the composition tetrahedron is formed
by the set of critical points on the solubility surface.
References
1. Sundmacher K., Weinheim Kienle A. Reactive Distillation: Status and Future
Directions. WILEY-VCH Verlag GmbH & Co. KgaA. 287. (2003).
2. Cherkasov D.G., Ilin K.K. // J. Chem. Eng. Data. 47. 1303. 23. (2002).
3. Sazonov V.P., Lisov N.I., Sazonov N.V.// J. Chem. Eng. Data. 47. 599.
(2002).
27
Solution – solid equilibrium in systems MX2 – H2O – S
(M – Cu, Co; X – Cl, Br; S – DMSO, DMF)
Gorbunov Artem, Tikhomirova Anastasia
[email protected]
Scientific supervisor: Dr. Skripkin M.Yu., Department of General
and Inorganic Сhemistry, Faculty of Chemistry, Saint-Petersburg
State University
Solid phase formation in ternary saline water-organic systems and particularly
generation of mixed water-organic crystallosolvates still remains one of the insufficiently explored fields of chemistry of heterogeneous systems. In continuation
of earlier systematic study of the effect of anion’s nature and properties of organic
solvent on the solution - solid equilibrium in the systems CuCl2 - H2O - S (S - dimethyl sulfoxide, N, N-dimethylformamide, acetonitrile, 1,4-dioxane) the study of
systems CuBr2 - H2O - S and CoX2 - H2O
Moles/100 moles
DMSO DMF - S was undertaken in this work.
of solvent
The results obtained show that solubilCuCl2
0.8
9.6
ity of MX2∙nDMSO is much differ from
CuBr2
2.0
20.4 that of MX2∙mDMF. The reason is much
higher structuring of neat DMSO comparCoCl2
0.5
10.9
ing with DMF. The solubility of copper
CoBr2
1.7
4.6
salts is generally higher than that of cobalt
compounds due to the difference between
the stability constants of halide complexes:
the higher stability of copper complexes
in solution leads to displacement of phase
equilibrium to dissolved forms.
The solubility in ternary systems obeys
the similar laws like in binary organic
solutions. For example, solubility of copper bromide higher that that of chloride
because ionic association is higher in the
latter case.
Crystallization fields of compounds
MCl 2∙xDMF are smaller compared to
Fig. 1. Structure of CoCl2*8/3DMF. MCl2∙xDMSO. This fact is correlated with
the difference in donor numbers of DMF and DMSO. Eight isotherms of solubility
were obtained and six new mixed crystallosolvates were synthesized in the course
of work. Their structures were investigated by single-crystal X-Ray diffraction and
IR spectroscopy (as an example structure of CoCl2∙8/3DMF is given in Fig. 1).
Russian Fund for Basic Research (project 09-03-00755-a) is greatly acknowledged for the financial support.
28
Effect of copper oxidation state on the structure of
complexes of copper chlorides with morpholine
Gorbunov Artem
[email protected]
Scientific supervisors: Dr. Skripkin M.Yu., Dr. Starova G.L.,
Department of General and Inorganic chemistry, Faculty of
Two coordination compounds of copper (I, II) chloride with organic ligand
morpholine have been synthesized and investigated. The composition of complexes
was determined with complexonometric titration and IR spectroscopy. Morpholine
molecules coordinate to copper atoms with nitrogen atoms in both complexes. The
structure of complexes was determined by the single-crystal X-Ray diffraction. The
results obtained show that in CuCl2∙3MP (MP – morpholine) copper atoms have coordination number five (Fig. 1) and are surrounded by two chlorine atoms and three
organic molecules. The polyhedron is distorted square piramide with morpholine
molecules in trans-position in basal plane (2.045 Å). The third organic molecule
occupies an apical position at the significantly longer distance (2.234 Å).
In complex CuCl∙2MP coordination polyhedron of copper atoms is triangle
(Fig. 2) with one chlorine atom and two nitrogen atoms (1.985 Å).
Fig.1 Structure of CuCl2*3MP.
Fig. 2. Structure of CuCl*2MP.
Russian Fund for Basic Research (project 09-03-00755-a) is greatly ��
acknowledged for the financial support.
29
Investigation of oxidation processes of iron oxidenanoparticles using NEXAFS-spectroscopy
Goroncy Christian
[email protected]
Scientific supervisors: Prof. Dr. Eckart Rühl and Prof. Dr.
Christina Graf, Freie Universität Berlin
Iron oxide nanoparticles are used in many applications, especially as contrast
agents in Magnetic Resonance Tomography (MRT). Modern syntheses, like thermal decomposition of iron oleate, offer a novel way of producing monodisperse
systems with small particle radii.
In the present study, oleic acid-stabilized iron oxide nanoparticles were prepared by thermal decomposition. Subsequently, the particles were tempered in
oxygen-free or oxygen-rich environment to improve their crystalline order and
to change their magnetite to maghemite ratio. The different nanoparticle systems
were investigated by transmission electron microscopy and dynamic light scattering before and after this thermal treatment. It could be shown that no aggregation
is caused by these post-synthetic oxidation processes.
Using NEXAFS spectroscopy (Near Edge X-Ray Absorption Fine Structure)
the local electronic structure of theses particles was studied and the results were
compared with those of bulk iron oxides (magnetite, hematite, and maghemite).
Especially, the NEXAFS spectra at the Fe-K edge allow characterizing which types
of iron ions are present in the samples and also yield information on the local environment of the ions. In this way, we could show that treating the nanoparticles with
oxygen at 150°C strongly increases the maghemite content of the nanoparticles. In
contrast, oxidation at temperatures below 120°C as well as heating the particles in
an oxygen-free environment at 150°C does only slightly influence the maghemite/
magnetite ratio of the iron oxide particles.
30
Solid-contact ion-selective electrodes with ion-to-electron
transducer layer composed of nanostructured materials
Ivanova Nataliya
[email protected]
Scientific supervisor: Prof. Mikhelson K.N., Department of
Physical Chemistry, Faculty of Chemistry, Saint-Petersburg State
University
Ion-selective electrodes (ISEs) – potentiometric sensors of electrolytes, are
routinely used in analysis of clinical, agricultural, industrial, and environmental
samples. Use of ionophores selectively binding ionic species allows for selective
assay of a large number of analytes. Therefore, ISEs with ionophore based polymeric membranes are of special interest. Unfortunately, this kind of ISEs, unlike
those with glass or crystalline membranes, show stable potential readings only
in the so-called conventional setup: with internal filling solution and a suitable
internal electrode, normally – Ag/AgCl. On the other hand, the presence of the
internal filling solution hampers the miniaturization of ISEs and does not allow for
the planar technology of the sensor production. The development of ISEs without
internal solution – the so-called solid contact ISEs (SC-ISEs), is a challenging task.
Some stabilization of the potentials of these electrodes can be achieved by use of
a transducer layer with mixed ionic and electronic conductivity, placed in between
the sensing membrane (ionic conductor) and substrate (electronic conductor).
We have studied K+-selective SC-ISEs with PVC membranes plasticized
with bis(2ethylhexyl)phthalate, containing various nanostructured materials in
the transducer layer between the membrane and graphite substrate. These were
(i) graphenes in combination with potassium hexacyanoferrates, the same doped
with dispersed carbon black (ii), or with fullerenes (iii), and Cu(I) -polymeric
nanocomposite material (iv).
All the ISEs showed near-Nernstian response in KCl solutions, however only
ISEs of the (iv)-th type showed normal lower detection limit: 10−5 M. The rest
showed 10−4 (ii), or even 10−3 M (i), (iii), which is unacceptable for most applications. SC-ISEs (i) and (iv) showed the best stability of the potentials over time,
although still worse than the conventional ISEs with internal solution. Electrodes
(iv) also showed the best piece-to-piece reproducibility, and therefore seem the
most promising. The insufficient stability of electrode potentials is, most likely,
due to high charge transfer resistance at the transducer layer registered by the acimpedance measurements. Lowering of this resistance will be our further task.
Prof. A. Yakimanski and Dr. M. Goikhman (Institute of Macromolecular compounds RAS, St.Petersburg) are kindly acknowledged for providing with Cu(I)
-polymeric nanocomposite.
31
Effect of nonionic surfactants on laser-induced copper
deposition process
Eugene M. Khayrullina, Sergey V.Safonov
[email protected]
Scientific supervisor: Dr. Kochemirovsky V.A., Department of Laser
Chemistry and Laser Materials Science, Faculty of Chemistry,
Saint-Petersburg State University
The interest in the laser-induced chemical liquid phase deposition (LCLD) of
metals is due to the prospects of application of this method in microelectronics
and technology, as it allows maskless manufacture of localized metallic structures
5-100 mkm wide. Focused laser beam scanning of the surface of a dielectric placed
into a special solution results in local initiation of chemical reduction to give metallic copper according to equation (1)
CuL(n–2)– + 2HCHO + 4OH– = Cu0 + Ln– + H2 + 2HCOO– +2H2O
(1)
where L is an organic complexing agent (in this case EDTA salts was used); formaldehyde serves as the reducing agent and is introduced in a 6 - 7.5 fold excess.
The copper salt used is most often sulfate or chloride [1].
An unsolved technical problem that prevents the practical application of
LCLD is intense gas evolution occurring around the laser beam focus point on the
dielectric surface. The formation of gas bubbles in the laser beam path leads to its
defocusing. As a result of this fact, metal deposition from solution is uncontrollably discontinued, or it occurs in a refracted or reflected irradiation zone. In such
a case, diffuse edges, areas with unsatisfactory topology are formed on the metal
deposited structure (ruptures, tails of the metal deposited in a non-localized way
and other flaws).
The mechanism of the influence of nonionic surfactants on the process of laser
deposition can be expected: non-ionic surfactant affects the process of formation
of gas bubbles at the focus of the laser beam, which in turn affect the topology of
the deposited copper structures. Also, non-ionic surfactant can moisten the surface
of the dielectric and promote the adsorption of copper ions in a complex on the
surface of the dielectric, thus activating it by creating a metallic activation centers.
As prospective non-ionic surfactants in this study were examined Empilan and
Tween in two modification and Sintanol. As a result of the work was obtained by
the qualitative dependence of the morphology of the deposited structures and the
formation of gas bubbles on the HLB value of surfactants.
References
1. Kochemirovsky V.A., Menchikov L.G., Safonov S.V., Bal'makov M.D., Tumkin
I.I., Tver'yanovich Yu.S. Laser-induced chemical liquid phase deposition of metals: chemical reactions in solution and activation of dielectric surfaces // Russian
Chemical Reviews 80 (9).
32
CsNdTa2O7 ion exchange reactions in the acidic solutions
Korvinson K.V. Chislov M.V.
[email protected]
Scientific supervisor: Prof. Zvereva I.A., Department of Chemical
Thermodynamics and Kinetic, Faculty of Chemistry, SaintPetersburg State University
Protonated forms of layered perovskite-like oxides, or Bronsted solid acids,
attracted an attention for a long time due to a number of physico-chemical properties that hydrogen derivatives of layered oxides possess. For example, they may
participate in ion exchange reactions and intercalation processes, exhibit photocatalytic properties [1], could be split to produce monolayers, etc. First of all,
these solid acids are promising as precursors for the low-temperature ion exchange
reactions. For example, tantalates of neodymium KNdTa2O7 and NaNdTa2O7 are
unstable at high temperature and cannot be synthesized by solid state synthesis
from the simple compounds, however these layered oxides more prone to interlayer
ion substitution and could be obtained from CsNdTa2O7 by the low-temperature
ion exchange reactions.
Moreover, CsNdTa2O7 is regarded as one of the most promising photocatalysts for water splitting into H2 and O2 under UV irradiation [2]. That is why the
investigation of the stability of this compound in aqueous acidic solutions has an
important practical value.
In this study were found intervals of acidity where: a) the original compound
CsNdTa2O7 is stable; b) the monophase product of substitution HNdTa2O7 could
be obtained; and c) the perovskite-type intergrowth structure of layered oxide
CsNdTa2O7 gets destructed.
The study was carried out at 20 and 80OC in range of acid concentration
from 0.01 to 10 M, CsNdTa2O7 was obtained by ceramic technology (1100°C and
10 h).
X-ray powder diffraction, X-ray fluorescent spectroscopy, SEM, thermogravimetry have been used for the investigation of structure, chemical content and
morphology of products of ion-exchange reactions.
Photocatalytic activity of obtained compounds and precursor was determined
for the photoinduced process of water splitting. The investigation of CsNdTa2O7
stability in acidic solutions with different pH values allows us to determine the
limits of acidity in which the compound can be used in photocatalytic processes.
References
1. Kudo A., Sakata T. // J. Phys. Chem., 1996, 43, 17323-17326.
2. Masato Machida, Kaori Miyazaki, Shigenori Matsushima, Masao Arai. // J.
Mater. Chem., 2003, 13, 1433–1437.
33
Synthesis, characterization and photophysical
properties of gold(I)-copper(I) alkynyl clusters with 1,4bis(diphenylphosphino)butane ligand
Krytchankou Ilya
[email protected]
Scientific supervisor: Dr. Krupenya D.V., Department of General
and Inorganic Chemistry, Faculty of Chemistry, Saint-Petersburg
State University
A series of novel intensely luminescent gold(I)-copper(I) alkynyl-phosphine
clusters of general formula [Au3{Ph2P(CH2)4PPh2}3Au3Cu2(C2C6H4X)6][PF6]2 (X =
NO2 (1), H (2), OMe (3), NMe2 (4)) was prepared by the self-assembly reactions,
starting from simple precursors. The compounds obtained were characterized by
NMR spectroscopy and ESI-MS measurements. The solid state structures of complexes (2), (3) and (4) have been elucidated by X-ray crystallography.
X
Au
X
n
+
PPh2
Ph2P
+
P
X
X
Cu
P
P
P
P
P
Cu
[Cu(NCMe)4][PF6]
Au
P = PPh2
X
X
X
The luminescence behavior of these compounds in solution has been studied
and intense room-temperature emission with maximum quantum yield of 0.66 (2)
was detected that is comparable with the luminescence properties of closely analogous complexes based on the 1,4-bis(diphenylphosphino)benzene ligand1. Slight
decrease in the luminescence quantum yield and hypsochromic shift of emission
maxima may be caused by absence of rigid π-conjugated aromatic rings between
phosphor atoms of the diphosphine ligand.
The authors greatly appreciate financial support of Saint-Petersburg State
University research grant 12.37.132.2011; RFBR grants 11-03-00974-a and 1103-00541-а.
References
1. Koshevoy I.O., Lin Y.-Ch., Karttunen A.J., Chou P.-T., Vainiotalo P., Tunik S.P.,
Haukka M., Pakkanen T.A. // Inorg. Chem., v. 48, № 5, p. 2094-2102, (2009).
34
Synthesis and structure of a new series of mononuclear
alkynyl-phosphine Au(I) complexes
Kulish Kirill, Shakirova Julia
[email protected]
Scientific supervisor: Dr. Grachova V.E., Department of Inorganic
University
Luminescent d10 transition metal complexes attract increasing attention because
of their rich photophysical properties and possible practical applications [1, 2].
In present work a new series of mononuclear alkynyl-phosphine complexes
of gold(I) were synthesized and characterized. All new compounds were obtained
according to Scheme 1.
Scheme 1.
Composition of complexes obtained was established on the basis of polynuclear NMR and IR spectroscopy. In addition, the solid structure of complex (2)
was elucidated by X-ray crystallography.
References
1. Koshevoy, I.O. et al. // Inorg. Chem., 2094-2102, 2009.
2. Koshevoy, I.O. et al. // Angew. Chem. Int. Ed, 3942-3945, 2008.
35
Creating microelectronic elements by laser induced deposition
of high-quality copper conductor for dielectric surfaces
Logunov Lev, Tumkin Ilya, Safonov Sergey
[email protected]
Scientific supervisor: Kochemirovsky V.A. Department of laser
chemistry and laser materials, Faculty of Chemistry, SaintPetersburg State University.
Ceramic and glass-ceramic materials are currently widely used in the manufacturing of microelectronic products. Photolitography is being used for printed
circuit boards production in industry. However, this method is multistage and not
environmentally friendly.
The development of single-stage methods of metallization, such as laser-induced
chemical liquid phase deposition (LCLD). is challenging problem for scientists
and engineers.
Laser-induced deposition of copper technique is based on the reactions that
occur during heating of the local volume of solution by a focused laser beam:
CuL( n − 2 ) − + 2 HCHO + 4OH − → Cu 0 + Ln − + H 2 + 2 HCOO − +2 H 2 O (1)
where L- one or more complexing ligands.
Previously, our laboratory has developed a technique to obtain the copper
structures on quartz glasses [1]. The aim of this study was to obtain high-quality
copper tracks on surfaces of commercially used ceramics Polikor VC-96 VC-100
Polikor and glass-ceramics Sitall ST-50-1, because oxide glass is almost never
used in microelectronics.
The deposition of copper tracks on the surface of ceramics Polikor VC-96
VC-100 Polikor and glass ceramics Sitall ST-50-1 with the use of formaldehyde
as a reducing agent (eq. (1)) resulted in high values of resistivity (more than
8 Ohm * mm2 * m-1) of copper lines[2]. To improve conductivity and topology of
the copper structures we used sorbitol as a reducing agent. The use of sorbitol can
leads to deposition of continuous copper tracks on the glass-ceramic ST-50-1, 1 cm
long, more with an electrical resistivity of 0.115 Ohm * mm2 * m-1. The results of
experiment have good reproducibility of geometric parameters and conductivity
of copper structures.
The use of sorbitol as a reductant in the reactions of laser-induced deposition
of copper offers the prospect of wide application of the method LCLD for micromanufacturing in electronics.
References
1. Tver'yanovich Yu.S. et al. // Mendeleev Communications, 21, 34-35 (2011).
2. Kochemirovsky V.A., Menchikov L.G., Safonov S.V., Bal'makov M.D.,
Tumkin I.I., Tver'yanovich Yu.S. // Russ. Chem. Rev., 80 (9), 905-920 (2011).
36
Using of semiconductor oxide films for detection of
volatile organic compounds in gases
Lopatnikov Artem
[email protected]
Scientific supervisor: Dr. Povarov V. G., Department of Analytical
University
One of the main problems of modern analytical chemistry is creating new
methods for the detection of volatile organic compounds with their preliminary
identification. Currently, gas-sensitive sensor systems based on semiconductor
films, are of widespread. Such sensors satisfy many requirements for gas chromatography detectors, and can be used for this purpose
The aim of the present work is the development of gas chromatographic detector
based on tin dioxide films, which modified by transitive metal oxides. Tin dioxide
is selected due to its pronounced semiconducting properties. One way to improve
the selectivity is a chemical modification of basis with the addition of oxidation
catalysts. The film surface of tin dioxide has the ability to high adsorption and
reactivity. The presence of volatile
Fig. 1
organic compounds in the flowing 2,4 n-C H
CH OH
CH COOH
gas leads to its adsorption on a sur- 2,2
(C H ) O
2,0
face of film with subsequent oxidation. The mechanism of oxidation 1,8
is accompanied by formation of 1,6
VO
1,4
the number of ionic and ion-radical 1,2
forms, which are come from va- 1,0
lence band to the conductivity 0,8
CuO
band, which temporarily increases 0,6
0
100
200
300
400
500
600
700
800
the conductivity of film.
��
The received dependence,
presented in graphical form, is Fig. 1. Typical view of analytical signal, meaused as an analytical signal. Fig. sured at two films of different composition.
1 shows its typical view. Signals were obtained simultaneously for the two films of
different composition. The measurements were carried out on gas chromatograph
‘LKhM-80’ with column (3mm*3m) packed with Inerton coated with 5% SE-30,
carrier gas – nitrogen with the rate of 30 ml\min, detector temperature – 400 oC.
Concentration of VOC – 10 mkg\l for each sample.
6
14
3
∆U(V )
2
5 2
3
2
37
5
Synthesis diaryl ethers in the presence of iron oxide (III)
as the promoting agent
Lyutkin Andrew
[email protected]
Scientific supervisor: Dr. Orlov V.Yu., Department of Organic and
Biological Chemistry, Demidov Yaroslavl State University
Synthesis of ethers is usually carried out by diaryl nitrohalogenbenzenes (or
other activated substrates) reaction with phenoxides anions in aprotic dipolar solvents. The process is carried out to give the nucleophilic attack of a particle in situ.
In this case the reaction medium is heterogeneous, as potassium carbonate (commonly used agent for the formation of phenoxides anion) is practically insoluble in
aprotic dipolar solvents. The resulting heterophase system has a significant influence on the rate and completeness of the implementation process of nucleophilic
substitution. Therefore, it is relevant is the modification of the system by making
the promoting additives that foster effective nanoreactors.
The literature contains data on the influence of organic complexes of iron in
the solid-phase reactions of nucleophilic substitution [1, 2]. It can be assumed that
the promoting effect may have, and inorganic compounds of iron, including the
solid phase. At the same time have an activating effect center, which presumably
are associated with features (including defects) of the surface structure. Due to
the fact that the course of the process is largely determined by the localization of
the reaction zone at the interface of reagents and products of critical importance
genesis of solid samples, determining the nature of the surface, the localization of
active sites, the structure of nanoreactor. The experiments using different samples of
hematite showed that the addition of this solid-phase component of the accelerating
flow process. The greatest influence on the process under study has iron oxide (III),
obtained from ferrous sulfate and passed additional mechanical processing.
An explanation of the observed effect. The iron oxide has a supporting role,
acting as a promoter of potash. This effect may be to ionizing effects on the crystal
lattice of potassium carbonate in places of contact phases or by antidiffusion potassium and iron ions in the surface layers of the lattice of hematite and potassium
carbonate, respectively. Presumably, that this effect leads to a weakening of ties
of K-O and Fe-O in the crystalline phases.
References
1. Thomas Ruhland, Kia S. Bang, Kim Andersen // J. Org. Chem. 2002. N. 67. P.
5257-5268.
2. J. Peter Storm, Carl-Magnus Andersson // J. Org. Chem. 2000. N. 65. P. 52645274.
38
Synthesis, characterization, luminescence and non-linear
optical properties of diimine platinum(II) bisacetylide
complexes
Melekhova Anna
[email protected]
Scientific supervisor: Dr. Krupenya D.V., Department of General
and Inorganic chemistry, Faculty of Chemisry, Saint-Petersburg
State University
Platinum(II) bisacetylide complexes have attracted considerable attention
over the last years due to their luminescent and non-linear optical properties [1].
A series of platinum (II) complexes (diimine)Pt(-C≡C-R’)2, where diimine is 2,2’bipyridine or 4,4’-di-tert-butyl-2,2’bipyridine and alkyne is biphenylacetylene
or terphenylacetylene, were synthesized and their photophysical and non-linear
optical properties were investigated.
R
R
N
N
Cl
Pt
Cl
H
R'
(i-Pr)2NH, CuI
R
N
R
R = H, t-Bu
R'
N
CH 2C l2
Pt
R'
;
R' =
All compounds were characterized using NMR spectroscopy, ESI mass-spectrometry and elemental analysis. X-Ray crystal structure of the complex containing
4,4’-di-tert-butyl-2,2’-bipyridine and terphenylacetylene ligands is reported. The
electronic absorption and emission properties of the complexes have been studied.
Room temperature phosphorescence was observed for the complexes in solution
with the luminescence quantum yield in the range 2,1-7,7% and excited-state
lifetimes in microsecond domain. All complexes under study exhibit two-photon
luminescence.
References
1. Castellano F.N., Pomestchenko I.E., Shikhova E., Hua F., Muro M.L., Rajapakse
N. // Coord. Chem. Rev., v. 250, p. 1819-1828, (2006).
39
Novel polymers with heteroaromatic structure as promising
membrane materials
Pulyalina Alexandra
[email protected]
Scientific supervisors: Prof. Toikka A.M., Department of Chemical
Thermodynamics and Kinetics, Faculty of Chemistry, SaintPetersburg State University; Dr. Polotskaya G.A., Institute of
Macromolecular Compounds, Russian Academy of Sciences and
Department of Chemical Thermodynamics and Kinetics, Faculty
of Chemistry, Saint-Petersburg State University
Membrane technology is widely used in industry for separation of liquid and
gas mixtures. The high separation properties are determined by specialties of
morphology and individual parameters of membranes. Thus, the development of
novel membrane materials and investigate their physico-chemical properties are
the primary tasks.
The object of present work is novel membranes based on polycarbamate
(PCA).
PCA is a polymer of heteroaromatic structure with unique properties such as
good mechanical strength and chemical resistance to majority organic solvents. The
aim of this work is the study of peculiarities of composition, structure and separation properties of PCA membranes. Morphology details were analyzed by scanning
electron microscopy. The membrane surface tension was estimated through the
measurement of contact angles by sessile drop technique. Membrane composition
and thermostability were characterized by thermogravimetric analysis.
Transport properties of PCA membranes were investigated in sorption tests and
pervaporation processes. Pervaporation is the promising membrane method allows
separate thermally unstable, azeotropic mixtures, isomers and compounds with close
boiling points. Transport of liquids through polymer matrix occurs due to specific
interaction between components of the separating mixture and the membrane
material. It was established that PCA membranes are effective in pervaporation
of water-alcohol mixtures, including azeotropic composition.
The work was supported by Russian Foundation for Basic Research (grant
09-03-00812). The authors acknowledge Saint-Petersburg State University for a
research grant (reg. № 12.0.105.2010 (01201052803)).
40
Mechanism of formation, thermal stability and
thermodynamic properties of cation-ordered layered
perovskite-type titanates NaNdTiO4 and Na2Nd2Ti3O10
Sankovich Anna, Blokhin Andrey
[email protected]
Scientific supervisor: Prof . Dr. Zvereva I.A., Department of
Chemical Thermodynamics and Kinetics, Faculty of Chemistry,
Saint Petersburg State University
Layered perovskite-type oxides possess a wide spectrum of physical and
chemical properties (electrical, optical, catalytic) depending on their composition
and structure. Moreover cation-ordered oxides are attractive as precursors in soft
chemistry roots for synthesis of new layered compounds.
In report we present results of the study on mechanism of formation, thermal
stability and heat capacity of titanates NaNdTiO4 and Na2Nd2Ti3O10 that belong to
the Ruddlesden-Popper phases and built by the intergrowth of alternating layers
– Perovskite type blocks and Rock-salt type slabs.
Mechanism of formation and thermal stability of layered oxides NaNdTiO4 and
Na2Nd2Ti3O10 has been investigated by isothermal annealing-quenching method
followed by X-ray powder diffraction, SEM analysis and methods of the thermal
analysis with constant speed of heating (TGA and DTA). The processes of phase
formation in Nd2O3–TiO2–Na2CO3 system has been studied in the range 750-1350K,
thermal stability of complex oxides has been studied in the range 1050-1350K and
1350-1650K, respectively.
The structure-chemical mechanism of oxides formation and decomposition and
temperature intervals of phase transformations are determined. The comparison of
oxides stability is carried out in terms of crystal chemistry. The essential contribution
in the phase transformations are brought by the effect accompanying change of the
coordination environment of Nd+3 (C.N. = 9, 12, 6) and Ti+4 (C.N. = 6, 5) cations
and considerable distortions of their coordination polyhedra. The difference in the
length of Na–O bond connecting P and RS layers results in the greater stability of
Na2Nd2Ti3O10 layered structure in comparison with the NaNdTiO4.
The heat capacity (Cp) of NaNdTiO4 and Na2Nd2Ti3O10 is measured in the range
of 7-368K and 5-368K by calorimetric method. Certain anomalies were observed on
curves of temperature dependence of a thermal capacity of samples. The increase of
heat capacity at temperature decrease is observed for Na2Nd2Ti3O10 at temperatures
below 7.4K that can be explained by anomaly of Shottki. The increase in speed of
change of a thermal capacity with temperature growth is fixed above 340K both
for NaNdTiO4, and for Na2Nd2Ti3O10. This phenomenon is likely to be caused
by the beginning of phase transitions. Standard heat capacity, entropy, derived
enthalpy and derived Gibbs energy for NaNdTiO4 and Na2Nd2Ti3O10 compounds
were calculated.
41
Digital spectrographic analysis of human biological
fluids for determination of microelements
Sergey Savinov
[email protected]
Scientific supervisor: Prof. Drobyshev A.I., Department of
Analytical Chemistry, Faculty of Chemistry, Saint-Petersburg
State University
Chemical elements being presented in the human body can be divided into two
groups, namely, essential and toxic. Toxic elements (xenobiotics), which penetrate
into the body usually from the environment, even in low concentrations damage not
only health but also human life. As for the essential elements, which are necessary
for life, a significant increase or decrease in their concentration can also lead to
disorder of normal body functioning. In this regard, very important and called-for
area of analytical chemistry is to develop highly sensitive, multi-element, reliable,
and available methods of express determination of microelements in biosubstrates
of organs and tissues, as well as in biological fluids of the body. In particular,
atomic emission digital spectrographic analysis with the excitation spectrum of
dried residue of sample from end of carbon electrode in an arc discharge satisfies
the above requirements.
The aim of this study is to develop this method for direct (without sample treatment) analysis of human biological fluids (as an example, saliva) for determination
the concentration of microelements in them.
The report presents the results of studies on which the procedures such as preparation of carbon electrode to apply sample on its end and to evaporate this sample
for obtaining a dried residue, the terms of the excitation spectrum of the sample
(current strength, interelectrode distance), and the parameters of digital registration
of spectrum by the photodiode linear detector MAES have been optimized.
The developed method was tested for the absence of influence of variations in
the concentration of matrix biological components and in the acidity (from 2 to 8
pH values) of the samples on the results of analysis. Application of this method
allows to determine 18 elements (Na, P, Ca, Mg, Si, Zn, Fe, B, Ti, Mn, Cr, Cu, Al,
Co, Ag, Pb, Sn, Cd) at a concentration 10-6-10-7 g/l in human saliva. The generalized data of the content of microelements in saliva from the analysis of 60 samples
are given in the report.
42
Design and synthesis of 3D organometallic architectures
from Au(I)-polyphosphines and tert-Butylamine
Shakirova Julia
[email protected]
Scientific supervisor: Grachova E.V., Department of Inorganic
University
Recent years have seen a surge of interest in the construction of discrete
molecular assemblies, since these architectures have a wide range of possible applications [1]. For example, these compounds can serve as hosts to accommodate
small molecules [2].
In present work we developed the method of synthesis of supramolecular
organometallic cages from Au(I) - polyphosphines and tBuNH2 building blocks.
The reaction of [THT2Au2dppb](PF6)2 and [THT3Au3tppb](PF6)3 {THT = tetrahydrothiophene, dppb = 1,4-bis(diphenylphosphino)benzene, tppb = 1,3,5-Tris(4diphenylphosphinophenyl)benzene} with H2O in presence of Et3N give the corresponding trigoldoxonium complexes [O2(Au2dppb)3](PF6)2 and [O4(Au3tppb)4]
(PF6)4 as white solids. Treatment of these intermediate compounds with tBuNH2
affords the triply bridging amide derivatives [tBuN2(Au2dppb)3](PF6)2 (Fig. 1(1))
and [tBuN4(Au3tppb)4](PF6)4 (Fig.1(2)).
Fig. 1. Schematic structures of cations [tBuN 2 (Au 2 dppb)3] 2+ (1) and
[tBuN4(Au3tppb)4]4+ (2). Phenyl rings omitted for clarity.
The final compounds were fully characterized by elemental analysis, ESI-MS,
1D (1H, 31P{1H}) and 2D (1H-1H-COSY) NMR spectroscopy. The solid state structure of (Fig.1(2)) was elucidated by X-ray crystallography.
References
1. Thomas J.A. // Dalton Trans., Advance Article (2011).
2. Koshevoy I.O., Haukka M., Selivanov S.I., Tunik S.P. and Pakkanen T.A. //
Chem. Commun., v. 46, p. 8926 -8928 (2010).
43
Modification of polylactide films by aminogroups for
cells cultivation
Shalak Ksenia
[email protected]
Scientific supervisor: Dr. Shved J.A., Department of Chemistry
of Macromolecular Compounds, Faculty of Chemistry, SaintPetersburg State University
Polylactide is a biodegradable synthetic polymer that has found wide application in biomedical technology in particular it is used for making scaffolds in tissue engineering. Polylactide is a polymer with rather good mechanical properties
and operational characteristics but the surface hydrophobicity and the absence of
functional groups lead to low biocompatibility of this polymer to living cells and
tissues. So that, modification of polymeric materials used in tissue engineering is
needed in order to remove these limitations.
In the present work modification of polylactide was carried out with the introduction of amino groups on its surface. There are many ester groups (-COO-) in
the polylactide molecules that make it possible to bond different amino groups by
reaction with various diamines. We used diamine L-lysine for polylactide film modification. This amino acid is a part of all proteins and contains two amino groups.
One can expect some of the benefits of modified polymers due to the bonding of
amino groups. Some of them decrease the hydrophobicity of the surface, receiving the active sites. Such biomolecules as collagen, gelatin or RGD-peptides can
be immobilized on these sites in the future for obtaining a biocompatible surface
possible for good cells grow.
Polylactide films were treated with aqueous-alcohol solutions of lysine with
different concentrations at different temperatures and at different times. The number of bonded amino groups was determined photometrically using reaction with
ninhydrine in dimethylsulfoxide.
As a result of this work it was shown that with increasing temperature, reaction time and the basicity of the reaction medium increases the number of attached
lysine. It was founded also the conditions of maximum lysine bonding to the surface:
temperature – 55°C, time – 120 min, the reaction mixture – i-propilyc alchohol/
water (3:1). The concentration of lysine in the reaction medium does not affect
the number of bonded lysine.
References
1. Goddard J.M., Hotchkiss J.H. // Progress in polymer science, 2007, Vol. 32,
pp. 698-725.
44
Synthesis of condensed imidazole derivatives with a
nodal nitrogen atom - pyrido[1,2-a]benzimidazoles
Sokolov Alexandr
[email protected]
Scientific supervisor: Dr. Begunov R.S., Department of Organic
and Biological Chemistry, Faculty of Biology and Ecology,
Yaroslavl Demidov State University
One group of compounds, which are high demand in contemporary applied and
experimental sciences, are condensed imidazole derivatives containing a bridging
nitrogen atom. For example, to such structures belong pyrido[1,2-a]benzimidazoles, which exhibit a high biological activity, and furthermore, due to the system
of conjugated bonds have fluorescent properties. By analysis of more than 240
literary sources, it was concluded that the most promising method of synthesis of
substituted pyrido[1,2-a]benzimidazoles is reductive cyclization of pyridinium
salts (Fig. 1). This method allows to realize the process selectively, with a high
yield of target products.
We investigated the main factors determining the reaction and the possibility
for further chemical modification of the resulting products.
R2
R1
R
N
+
Cl
X
R3
O2N
R3
X
Cl
R2
N
+
2 a-g
NO2
..
X
[H]
N
+
R2
R3
X
Nu
N
N
R1
R1
R
1 a-c
Cl
R2
R3
3,4
R
R1
R
5,6
1 a) R=R1=H, b) R=R1=CH3, c) R=H, R1=CH3;
2 X=CH, a) R2=H, R3=CF3, b) R2=H, R3=CN, c) R2=H, R3=COOH, d) R2=H,
R3=CONH2, e) R2=R3=CN; f) R2=H, R3=NO2 g) X=N, R2=R3=H;
3,5 Х=CH; 4,6 Х=N
Fig. 1. Scheme of reductive cyclization of pyridinium salts.
As a result of investigations were selected optimal synthesis conditions, which
allowed to obtain the desired products of high purity and high yields. Based on experimental data and quantum-mechanical simulation was set key stage of reduction
of the nitro group, which determines way of the process of reductive cyclization
of pyridinium salts (Fig. 1) and was proposed the mechanism of intramolecular
reductive cyclization.
36-substituted pyrido[1,2 - α]benzimidazoles, which were obtained in our
research have been investigated as drugs, with mechanism of action is based on
intercalation into DNA and inhibition of replication of target cells. Among them,
the greatest biological activity have structures containing amino, amido, or both
amino and amido groups. Such drugs have high intercalary activity, which exceeding the known DNA intercalators in a few times.
45
Aggregation processes of gold nanoparticles and CdSe/
ZnS quantum dots using multivalent ligands
Stein Benjamin
[email protected]
Scientific supervisor: Prof. Graf C. Department of Chemistry,
Freie University Berlin
The influence of the colloidal stability of nanoparticles functionalized with
multivalent ligand was studied. Aggregation rates of gold nanoparticles and CdSe/
ZnS core-shell quantum dots, which are stabilized with mono- or multivalent [1]
ligands were analyzed at different pH, buffers and temperatures.
The ligands consist of thiol-terminated compounds and are also hydrophilic due
to a polyethylene glycol unit, and can therefore be applied in the pharmaceutical
field. The extent of aggregation of gold nanoparticles was determined from the
position and width of the surface plasmon resonance bands in the UV-Vis absorption spectrum. Time- and pH-dependent measurements indicate that the divalent
ligands undergo slower aggregation process than the monovalent one.
In addition, the divalent-protected gold nanoparticles exhibit a greater stability
at elevated temperature. Similar studies will be done on quantum dots and will be
characterized using fluorescence and UV-Vis absorption spectroscopy.
References
1. Mei B.C., Susumu K., Medintz I.L., Mattoussi H. // Nat. Protoc. 2009, 4,
412.
46
Application of gas chromatography to the investigation
of solution – solid equilibrium in the systems
salt – S – H2O (S – DMSO, DMF, 1,4 - Dioxane)
Tikhomirova Anastasia, Gorbunov Artyom
[email protected]
Scientific supervisors: Dr. Skripkin M.U., Dr. Povarov V.G.,
Department of General and Inorganic Chemistry, Faculty of
The establishment of the effect of competitive solvation of ions in the liquid
phase on the solution – solid equilibrium in multicomponent saline water-organic
systems is of great interest to development of methods of liquid-phase synthesis of
new materials. To the present time the number of papers devoted to this problem is
very limited. To a great extent this fact is caused by the difficulties in choose of the
appropriate analytical methods to determine the content of each component in this
type of systems. This problem arises from the ability of metal ions to coordinate
the organic component, which in case of use of standard methods of analysis can
lead to inadequate results.
To determine the content of the saline components complexometric titration
is rather suitable in most cases. However, the use of titrimetric method for the determination of the organic component in the saline systems involves considerable
difficulties. That is why it seems to be rather actual to fulfill some kind of work
with the particular task to establish the true content of organic component in the
mentioned above systems by means of gas chromatography method. The main
advantages of this method are the speed of analysis, the possibility of its automation, as well as the accuracy of the analysis.
Quantitative gas chromotographic analysis of mixtures consists from two main
steps: (1) Selection of conditions for the separation of water – organic solvent
mixtures with subsequent processing of the data that includes an experimental
determination of temperature, pressure and speed of carrier gas for optimal separation of mixtures. Gas chromatographic analysis was performed on packed column
3 mm * 3 m with a phase of Carbowax-20M on inertone and thermal conductivity detector – katharometer. Optimal speed of carrier gas and pressure are 30 ml
per minute and 1.05 atm respectively, temperatures analysis depend on organic
component (Table below). (2) Fulfillment ofchromatographic analysis for ternary
mixtures, which differ from the above mentioned by the presence of a specific
saline component.
Solvent
DX
DMSO
DMF
This method was applied to
t of column
120
150
170
determine solubilities of salts
in oC
in the wide number of ternary
systems MX2 – S – H2O (S = DX, DMSO, DMF, M = Cu2+, Cd2+, Co2+, X =Cl-,
Br-, SO42-).
47
Properties hybrid macromolecular antioxidants based
on hydroxyethyl starch and sterically hindered phenols
Zavyalova Margarita
[email protected]
Scientific supervisor: Dr. Domnina N.S., Department of
Macromolecular Chemistry, Faculty of Chemistry, SaintPetersburg State University
At the present time, the chemistry of phenol antioxidants has reached its apex
and simple variation of molecular elements does not gain a significant change
of antioxidant effectiveness. Thereby it is very perspective to synthesize hybrid
macromolecular antioxidants combining in structure valuable macromolecular and
antioxidant properties as regulators of free-radical processes.
We have developed hybrid macromolecular phenol antioxidants based on hydroxyethyl starch and functional derivatives of sterically hindered phenols. Hybrid
antioxidants with different degree of substitution were prepared by variation of
reaction conditions and, as was expected showed different solubility in water and
its mixtures with organic solvents. We have found that anti radical activity of the
synthesized compounds is considerably higher compared to low molecular weight
phenol antioxidants and is dependents on the nature of covalent spacer between
polymer and phenol.
Molecular properties of hybrid antioxidants were investigated by means of
DLS and TEM. It was shown that the structures in water solutions are represented
mainly by single macromolecules and do not form associates.
In vitro and in vivo tests proved that the designed hybrid macromolecular antioxidants possess high antioxidant activity as well as membrane stabilizing and
cardioprotector properties. The study indicates that these compounds might serve
as active components of blood plasma replacement and cardioplegic solutions.
48
B.Geo- and Astrophysics
The double-square root approximation for converted waves –
a pragmatic approach implementation
Abakumov Ivan, Schwarz Benjamin
[email protected]
Scientific superisors: Prof. Dr. Kashtan B.M., Department of Earth
Physics, Faculty of Physics, St.-Petersburg University, Prof. Dr.
D. Gajewski, Department of Geosciences, Institute of Geophysics,
University of Hamburg
Over the past years, multi-parameter stacking has become a standard tool for
seismic reflection data processing. Although several traveltime approximations
for converted waves may be found in literature, all of them are designed for the
common-mid-point geometry and are not applicable to an arbitrary distribution
of source-receiver pairs.
Recently the so-called double-square root tSq approximation for converted waves
was introduced which is valid for arbitrary observation geometries and curved
reflectors [1]. It was demonstrated that for converted waves this approximation
is applicable to large offsets and in the case of non-converted waves it provides
better results than other multi-parameter moveout formulas.
In this work the pragmatic search strategy for the double-square root tSq approximation of converted waves is introduced. The key step of the strategy is the
simulation of a zero-offset section by the stack of so-called γ-CMP gathers. These
gathers can be considered as the first approximation of common conversion point
gathers. For the case of monotypic waves this approach reduces to the well-known
pragmatic CRS search strategy of Müller et al. [2]. The CRS-type approximation
for converted waves is derived from the tSq approximation. It is shown that the
processing of converted waves with a PP-type operator, leads to incorrect values
of wavefield attributes. The processing of converted waves with the tSq operator
does not require the separation of PP and PS reflections. Effective wavefield attributes of converted and monotypic waves obtained by the corresponding type of
the operator display comparable values and may be used in a joint interpretation.
The difference in subsurface illumination and reflection coefficients of PP and
PS events allows to obtain a better image in some parts of the PS stacked section
compared to the PP section.
References
1. Abakumov I.V., Kashtan B.M. Traveltime Approximation for Converted Waves
// 73rd EAGE Conference & Exhibition P072, 2011.
2. Müller T., Jäger R. and Höcht G. Common reflection surface stacking method
- imaging with a unknown velocity model // 68th Ann. Internat. SEG Mtg., New
Orleans, USA, Expanded Abstracts, pp. 1764–1767, 1998.
50
New exact solutions of the Grad-Shafranov equation for
the 2D asymmetric current layers
Ainov Matsak
[email protected]
Scientific supervisor: Prof. Semenov V.S., Department of Earth’s
Physics, Faculty of Physics, Saint-Petersburg State University
Grad-Shafranov (GS) equation describes the kinetic equilibrium of plasma
embedded into magnetic field, in particular the space current sheets. GS equation
can be derived from the Vlasov equations with self-consistent electromagnetic
field [1, 2]. It is known (Walker, 1915), that the exact solutions of the GS equation
can be obtained by use of a special complex function g(ξ) which is responsible
for the current sheet structure [6]. Up to now it were obtained only symmetric
solutions which are not enough to describe the structure of the real space current
layers. For example, the symmetric current sheet in the Earth’s magnetotail happens to be only twice per year during the spring and autumn equinox. Therefore
it was suggested to extend the well-known classes of the exact kinetic solutions
(Harris, Fadeev, Kan and Manankova) [3] of the GS equation for the asymmetric
current sheet configurations by use the appropriate complex Walker function g(ξ).
As a result a new class of asymmetric kinetic current sheet equilibrium has been
obtained and investigated.
References
1. Сергеев В.А., Цыганенко Н.А. Магнитосфера Земли. –М.: Наука, 1980.
2. Пудовкин М.И., Самсонов А.А. Дополнительные главы магнитное
гидродинамики и физики плазмы, лекции для магистров.
3. Yoon P.H., Lui A.T.Y. // Journal of Geophysical research, vol.110, A01202,
doi:10.1029/2003JA010308, 2005.
4. Tsyganenko N.A. // Journal of Geophysical research, 5599-5612, 1995.
5. Tsyganenko N.A., Peredo M. // Journal of Geophysical research, 99, 199,
1994.
6. Walker G.W. Some problems illustrating the forms of nebulae // Proc. R. Soc.
London, Ser. A, 91, 1915, 410.
51
Influence of IMF Bx-component on the magnetotail
dynamics
Amosova Mariya
[email protected]
Scientific supervisor: Dr. Sergeev V.A, Department of Earth's
Physics, St.-Petersburg State University
Using global MHD simulation we investigated the influence of interplanetary
magnetic field (IMF) Bx-component on the configuration of the magnetotail and
especially on the tail neutral sheet (NS) geometry. Two simulations with Bx=-6nT
and Bx=6nT were performed. We used stable solar wind (SW)/IMF parameters during both simulations expect IMF Bz that had time-dependent variations. Simulations
show large Z-displacement of the tail NS depending on IMF Bx sign (goes up for
Bx<0, down for Bx>0). The magnitude of NS displacement also depends on radial
distance and increases in tailward direction achieving values 2-2,5 Re at X=-30Re.
It was found that NS vertical motion has two different modes. The first one connects to asymmetric energy loading into the North and South tail lobes. The second
mode associated with substorm expansion phase. Processing of Geotail observed
data for 1995-2005 in general confirms the global MHD results. The observed
displacement have an average magnitude 1 Re in the same direction as obtained
from MHD simulation.
52
Evolution of large-scale long-lived magnetic structures,
derived from synoptic Hα charts
Avramenko Evgeniya, Abakumov Ivan
[email protected]
Scientific supervisor: Dr. Ponyavin D.I., Department of Earth’s
Physics, Faculty of Physics, St.-Petersburg University
We analyzed Makarov and Sivaraman catalogue [1] of magnetic field charts
displaying the distribution of large-scale magnetic field inferred from H-alpha
observations during solar cycle 19. This distribution is strongly complicated by
small-scale fields and has a very difficult structure. In order to simplify the structure and reduce the influence of small-scale magnetic fields the averaged charts
method was developed [2]. According to this method to obtain the averaged chart
it is necessary to stack a few charts before and after the desired one. This method
gives acceptable results in comparison with satellite data and Stanford charts of
magnetic field. Averaged synoptic charts provide insight on evolution of long-lived
magnetic structures.
We improved averaged chart technique by taking into account the shift of
magnetic structures caused by differential rotation of the Sun, meridional flow and
evolution of field. In the first approximation the complex movement of structures
may be described by three velocities: horizontal velocity of Sun as whole, poleward
velocities in South and North hemispheres. We designed an algorithm for automatic
determination of these velocities for pair of charts based on the correlation of topologically similar parts of charts. The implementation of the algorithm leads to
construction of so-called optimal shifted averaged charts which allow to analyze
the behavior of long-lived magnetic structures during the reversal process.
Study of the behavior of large-scale magnetic structures in pole zones led us to
the fact that after simple reversal a strong structure is formed in the pole. We could
not find such a structure in the Northern hemisphere during the tree-fold reversal.
We have found that the poleward velocity of magnetic structure during the threefold reversal was in 2-3 times higher than one in the simple reversal. High poleward
velocity and absence of clearly seen large-scale magnetic structure after the reversal
doubt us whether the multiple reversal in cycle 19 really took place.
References
1. Makarov V.I., Sivaraman K.R. 1986, Atlas of H-alpha synoptic charts for solar
cycle 19 (1955 -1964). Carrington solar rotations 1355 to 1486. Kodaikanal Obs.
Bull., Vol. 7, 138 pp.
2. Bazhanov A.A., Ponyavin D.I. 2007, Large-scale organization and dynamics
of solar magnetic fields in solar activity cycle, Section B, Astrophysics and Solar
Physics, BShFF-2007, pp. 194–195.
53
Fractal characteristics of the ULF emissions during
quiet and disturbed conditions based on the data of 210
MM stations
Bondareva Tatiana
[email protected]
Scientific supervisor: Dr. Smirnova N.A., Department of Earth's
Fractal analysis of ULF emissions – fluctuations of the Earth’ magnetic field in
the ULF (f=0.001-1 Hz) range, - have been fulfilled based on the magnetic records
(1Hz sampling rate) of the 5 stations situated along the 210 geomagnetic meridian
(210 MM). The profile is lasted from the low latitude to the auroral zone. This
chain of stations includes the Guam, Moshiri, Paratunka, Magadan and Chokurdakh
locations. 22 months period (1992-1994) that embodies the date of the strong
Guam earthquake of 8 April 1993 is analyzed. We have used the Higuchi method
to get the stable values of fractal characteristics (fractal dimensions D and spectral
exponents β). Dependence of D and β versus Kp index of geomagnetic activity has
been analyzed. It is shown that fractal dimensions decrease and the corresponding spectral exponents increase with increasing of Kp index. Dynamics of D and
β have been investigated in relation to the quiet and disturbed conditions as it is
followed from the Dst index dynamics. It is revealed that ULF emissions change
their behavior from antipersistent regime (during quiet conditions) to persistent
regime during geomagnetic disturbances. The results obtained are considered on
the basis of the SOC (Self-organized criticality) concept.
54
Investigation of plasma injections into the inner
magnetosphere
Chernyaev Ivan
[email protected]
Scientific supervisor: Prof. Sergeev V.A., Department of Earth’s
Many recent studies show that the main contribution to the Earthward plasma
convection from the magnetosphere plasma sheet provide bursty bulk flows (BBFs).
In this study we define their basic charactericstics and evaluate their plasma and
magnetic parameters, taken from the Geotail satellite, when the latter was at the
center of the plasma sheet at a distance of 8-13 RE from the Earth. The fact of the
penetration into the inner magnetosphere was determined from data of the LANL
satellites, located at geostationary orbit. To estimate the volume of earthward moving plasma tubes we used the formula by Wolf et al (2006). In the model of plasma
bubble, the motion is primarily due to lower values for the entropy SB= PVγ, which
is the cause of the electric polarizarion bubble because of the difference currents
inside and outside. Confirmation of this model is that the BBFs with lower values
of entropy SB and large amplitudes of dipolization have a better chance to penetrate
into the inner magnetosphere, as well as the fact that the penetration depth of the
BBFs is independent of its initial velocity. However, it turned out that the entropy
parameter has a dependency on the radial distance, which contradicts the model
of a plasma bubble. From the analysis of baseline characteristics (parameters of
the plasma around BBF) we obtained the expecting result, which is that the depth
of penetration also depends on the state of the magnetosphere. Not expected and
interesting result was that the percentage of BBFs penetrating into the inner magnetosphere increases with decreasing distance from the registration point to the
inner magnetosphere. Thus, this study identifies the key parameters that control
the penetration depth of the BBFs and provide some evidence infavor of the model
of a plasma bubble.
55
Slow fluid wave in a symmetric trilayer model
Danilovskaya Ludmila
[email protected]
Scientific supervisor: Prof. Dr. Kashtan B.M., Department of
Earth’s Physics, Faculty of Physics, Saint-Petersburg State
University
The Krauklis wave is a slow dispersive wave mode that propagates in a fluid
layer bounded by elastic media [1]. There are indications that Krauklis wave plays
a significant role in a variety of wave propagation phenomena in seismology, acoustics, engineering and hearing physiology. This is defined by its large amplitudes,
high dispersion and confinement to the fractures filled with fluid (Fig. 1). In the
prospecting seismology Krauklis wave might be an important component of the
hydro-fracturing, seismic wave propagation in fractured reservoirs, and fracture
detection.
In this paper, we consider propagation of the interface waves for a model of a
fluid layer enclosed between two elastic plates and demonstrate that Krauklis wave
can be observed in a laboratory scale model within seismic frequency range.
H
H
Krauklis wave
depth (m)
depth (m)
Krauklis wave
H
H
Fig.1 Radial (a) and vertical (b) components of the displacement field for a vertical receiver line with 5 m offset from the source. Vertical components are amplified by the factor of 100. H- thickness of elastic plate.
The obtained asymptote solutions revealed good coincidence with the exact
solutions. The found analytical conditions accurately evaluate the transitions between different asymptote. Resonance conditions for the Krauklis wave predict
existence of resonances within the seismic frequency range at a laboratory scale.
If verified, this will allow experimental studies of the Krauklis waves in a variety
of realistic models that simulate fractures filled with fluids.
References
1. Krauklis P.V. About some low frequency oscillations of a liquid layer in elastic
medium, Prikladnaya matematika i mekhanika, 26, 1111-1154.
56
Signatures of atmospheric long-period oscillations in
seismometric data
Ermolenko Svetlana
[email protected]
Scientific supervisor: Prof. Shved G.M., Department of Atmospheric
In the 1970s Lin'kov with colleagues from St. Petersburg University [1] first
detected oscillations of much longer periods than 1 day from records of zero drift
of vertical seismometer. For example, strong oscillations of ~ 15, 25, and 50 day
periods have been revealed. However the origin of these oscillations remained
unclear.
The aim of the given work is to check the possibility of interpretation of these
oscillations as effect of influence of planetary waves on the seismometer.
Here, we analyze measurements, made by a three-channel seismometer at Collm
Observatory (51.3°N, 13°E) in 2002, together with simultaneous measurements
of atmospheric pressure variations by a microbarometer. Power spectra have been
obtained for the Z-, N-, and E-channels of the seismometer. These spectra show
oscillations at periods of several days for all of the channels. Likewise, the spectra
of pressure variations shows a strong features similar periods. The comparisons
of seismometric running spectra for all the channels and with microbarometeric
running spectrum have been made for annual series over the 30-day window sliding along the series with the 1-day step. As a result, common features in the 3 - 20
day period range have been confidently revealed in all four running spectra. In
particular, joint spectral peaks have ben found in the pressure and Z-componnet
series in summer, and in the pressure and N-componet in winter. The frequencies of common spectral features change with time. The features in seismometric
spectra may be explained as signatures of planetary atmospheric waves. For now,
a physical mechanism of action of planetary waves on the 'mass' of seismometer
remains unknown yet.
This study was supported by German-Russian Interdisciplinary Science Center
(Project G-2011a-1).
References
1. Lin'kov E.M. Seismic phenomena. Leningrad University Press, (1987).
57
Head waves in the full waveform inversion
Kazei Vladimir
[email protected]
Scientific supervisor: Dr. Kashtan B.M., Department of Earth’s
Full waveform inversion is now one of the most modern and effective methods of geophysical data processing, usually used for parameters reconstruction
with different observations schemes. The main idea of this method is established
long time ago and one of the most correct formulations can be found in the work
by [1] which states Inversion = Migration + Tomography. The author considers
a 2d problem with a horizontal layer over the halfplane and shows the spectrum
recovered with full wave data.
Improvements for this paper results are established at the same simple model
after a deep investigation. One of the most significant of them is that we give an
estimate for the head waves influence on the velocity recovering. Diagrams for
the inhomogeneity spectrum parts are plot with use of head waves answering the
question about the domain in the space spectrum of heterogeneity which can be
reconstructed on this type of waves.
References
1. P. Mora. Inversion = migration + tomography. - Geophysics, 1989.
58
The application of projection operators to the studding
of atmospheric waves
Lebedkina Anastasia
[email protected]
Scientific supervisor: Dr. Karpov I.V., Department of Theoretical
Physics, Immanuil Kant Baltic State University
Traditionally, in the experimental studies of the wave structure of the atmosphere determine the frequency of the waves. These data are generally insufficient
to establish the type of wave disturbances as determined by the spatial scale of no
waves. To find the spatial scales involved are usually spaced observations in space
stations. The accuracy of this approach is low, but the problem may be obtained
by methods of projection operators that allow you to identify the observed wave
field of the contribution to the well-known wave type in the observed wave field.
The idea is that the initial field is a superposition of waves of known types.
Solution of the problem is to construct the projection operators and their application
to the wave field. The use of projection operators allows us to passon the solution
of the original system to solve the evolution equations for the eigenvectors of L.
Then, using the polarization ratio, to receive the initial system of equations, which
in many cases, greatly simplifies the process of finding solutions.
Capabilities of the method of projection operators are shown to the analysis
of planetary waves in the model of “shallow water” describing the Poincare and
Rossbi waves.
59
Creating software for processing GPR data
in the auto mode
Mikhalaki Nadezda
[email protected]
Scientific supervisor: Dr. Krylov S.S., Department of Earth’s
Over the years, experience of using GPR (ground penetrating radar) for solving various problems in the subsurface part of the section is growing constantly.
However there is not enough number of programs for processing GPR data. There
is a possibility in a number of standard applications to use ready tools which will
improve the quality of the collected data for following processing. The further
problem of constructing a section of the subsurface environment is solved by the
visual analysis of the wave pattern and tracing of coherent lineups from the reflected signals, which correspond to the boundaries between layers with different
electrophysical parameters.
Since in reality the layers do not always have sufficiently high dielectric contrast,
it takes enough time to construct the section. But in the field, it is often necessary to
evaluate the approximate distribution of electrical parameters of the environment,
quality of work. Thus, it is evident that there is hard necessity of creation software
that allows getting the first approximate results in real time.
It is known that the theory of GPR uses three main types of waves: direct, reflected and diffracted. Only last one is considered in this work, because hodograph’s
shape of the diffracted wave depends only on the properties of host rock. Thus, the
determination of the velocities of electromagnetic waves in the medium and the
subsequent construction of the section of the permittivity is reduced to constructing
an algorithm of automatic search for the hyperboles on radarogramms.
Synthetic radarogramms were made for use as initial data. Algorithm proved
to process well such a data. Also was used experimental data collected during the
summer practice at the White Sea (it was included in the geophysical master’s
program).
References
1. Denisov R.R., Kapustin V.V.// Geophysics, № 4, p. 76 (2010).
2. Vladov M.L., Starovoytov A.V.// Introduction to GPR, p. 20 (2004).
60
Interacting galaxies at z~0.7
Mohamed Y.H.
[email protected]
Scientific supervisor: Prof. Reshetnikov V.P., Department of
Astrophysics, Faculty of Mathematics and Mechanics, SaintPetersburg State University
The morphologies of galaxies in several deep fields (HDF-N, HDF-S, HUDF,
GOODS, GEMS) of the Hubble Space Telescope are analyzed visually. Lists are
made of the galaxies with tidal structures (tails, bridges) and M51-type galaxies in
these fields. Photometric characteristics and estimated redshifts for most of these
objects are found in the published literature. A total of 29 candidate M51-type
galaxies and 381 galaxies with tidal structures are discovered in three of the fields
(HDF-N, HDF-S, HUDF). More than two hundred interacting galaxies are found
in the regions of each of the GOODS and GEMS projects. These data constitute
the largest sample of interacting galaxies among distant objects currently available
in the literature [1].
In the second part of our work, we presented the results of analysis of the frequencies of galaxies with tidal tails and M51-type galaxies in several deep fields
of the Hubble Space Telescope (HDF-N, HDF-S, HUDF, GOODS, GEMS). The
sample of galaxies is based on our catalog of interacting galaxies in these fields
[1]. In total, we have found about seven hundred interacting galaxies at redshifts
z < 1.5 in these fields. At z < 0.7, the observed space densities of galaxies with
tidal structures and M51-type galaxies have been found to increase as ∞ (1+z)m,
where m ≈ 2.6 [2].
According to our estimates, over the last 6-7 Gyr, i.e., at z < 0.7, about a third
of the galaxies with absolute magnitude M(B) < -18 mag must have undergone
strong gravitational perturbations and mergers and ~1/10-1/5 of the galaxies have
accreted relatively low-mass nearby satellites typical of M51-type galaxies. The
possible decrease in the timescale on which a distant galaxy appears peculiar with
growing redshift can increase considerably the estimated rate of mergers.
The high galaxy merger rates found from observations of distant objects clearly
suggest that gravitational interactions and mergers were among the most important
processes that determined the individual properties of the galaxies surrounding us.
Furthermore, they affect the evolution of the “luminous” matter in the Universe as
a whole, because galaxy mergers change the luminosity function of galaxies, the
luminosity density produced by them, and other characteristics.
References
1. Y.H. Mohamed, V.P. Reshetnikov // Astrophysics, v.54, p. 155 (2011).
2. V.P. Reshetnikov, Y.H. Mohamed // Astron. Lett., v.37, p. 743 (2011).
61
Waveform inversion of microseismic data for
permeability estimation
Renat Shigapov
[email protected]
Scientific supervisor: Prof. Kashtan B.M., Laboratory of Elastic
Media Dynamics, Department of Earth’s Physics, Faculty of
Physics, Saint-Petersburg State University
The estimation of poroelastic properties of reservoir rocks is a very important
and topical problem [1]. In this work we focused on the permeability estimation
[2]. Assuming that the input data were obtained during hydraulic fracturing experiments [3, 4], our goal was to estimate the rock permeability using full waveform
inversion of microseismic records. Using certain values of microseismic source
location, timing, and mechanism [5], we have successfully tried the elastic full
waveform inversion of the rock permeability on the synthetic data in the Born approximation generated for the crosswell (the vertical and horizontal well) geometry
with the irregular distribution of receivers. We used a quasi-Newton algorithm to
minimize a misfit function between the observed and synthetic elastic (P + S) wave
fields. We also used the grid search method to show a cost function behavior. Prior
to inversion we used trace normalization and time-domain gating of the observed
displacements. Assuming that the true permeability value is 5·10-10 m2, we have
done a set of numerical tests in order to study stability of the method to noise and
velocity model errors. We have shown that our method is rather stable to noise, if
the initial value of permeability is close to the exact one. However, even 5% errors
in a velocity model can lead to method failure. It would be reasonable in our future
research to fit a velocity model simultaneously with a permeability inversion.
References
1. de Barros L., Dietrich M., Valette B// Geophysical Journal International, Vol.
182, Issue 3, 2010, P. 1543-1556.
2. Shapiro S. A., Dinske C., and Rothert E. //Geophysical Research Letters, 33,
2006, L14312.
3. Grechka V., Mazumdar P., and Shapiro S.A. //Geophysics, 75, Is. 1, 2010, P.
B1-B10.
4. Pride S.R. et al. Permeability dependence of seismic amplitudes: TLE, June
2003, P. 518-525.
5. Droujinine A.B., Oates S., Ita J. Elastic Full Waveform Inversion for Locations
and Moment Tensors of Microseismic Events: 73rd EAGE Conference &
Exhibition, Vienna, Austria, 2011.
62
Subsolar magnetic barrier properties in dependence of
interplanetary parameters
Slivka Kirill
[email protected]
Scientific supervisor: Dr. Dmitrieva N.P., Department of Earth’s
When the supersonic solar wind flows around the magnetosphere the magnetic barrier is formed in the inner magnetosheath layer adjacent to the dayside
magnetopause. The magnetic barrier is the region of enhanced magnitude of the
magnetic field and decreased values of plasma density. If there is no reconnection
it doesn’t depend on the orientation of the interplanetary magnetic field. The other
way it does. The magnetic barrier is on average absent in the case of southward
magnetic field in the magnetosheath [1]. But it is not always true. In this regards,
it has been tasked to find experimental evidence for the existence of the magnetic
barrier in the case of southward magnetic field.
We have studied low-latitude dayside magnetopause crossings by the Themis
satellites. The variations of the magnetic field and key plasma parameters in the
magnetosheath have been investigated to distinguish the fact of existence of the
magnetic barrier for any direction of the magnetic field in the magnetosheath.
According to our preliminary results the magnitude of the magnetic barrier field
may be the same order for the strictly southward IMF as for the northward.
References
1. Phan T.-D., Paschmann G., Baumjohann W., and Sckopke N. // J. Geophys.
Res., v. 99, № A1, p. 121-141, (1994).
63
A study of global electric current distributions in the
geomagnetosphere,
based on spacecraft magnetometer data
Yurina Agata
[email protected]
Scientific supervisor: Dr. Tsyganenko N.A., Department of Earth's
The goal of this work is to study the global structure of the equatorial current
sheet in the Earth’s magnetosphere using a sliding modeling method. The essence of
the approach is to divide the entire modeling domain into a set of adjacent spatially
limited cells, so that the electric current density in each cell can be represented
by a simple locally planar distribution of the vector j=(c/4π)×B shifted with
respect to the equatorial plane (in GSM coordinates) and rotated around XGSM and
YGSM axes. The shift and rotation angles for each cell are derived from spacecraft
magnetic field measurements using a simple local model, whose coefficients are
fitted to local subsets of data that belong to the cell. The work uses the data of the
following spacecraft: Polar (1996-2003), Cluster (2001-2007), Geotail (1995-2005),
and Themis (2007-2010).
The sliding modeling revealed global distributions of the electric current density
in the magnetospheric equatorial current sheet, its average shape and thickness as
functions of the Earth’s magnetic dipole tilt angle with respect to the terminator
plane. By sorting out the data into bins of the Akasofu’s solar wind - magnetosphere
coupling index, we derived the dependence of the equatorial current configuration
and magnitude on the solar wind state.
64
С. Mathematics and
Mechanics
Programming technology for multi-agent controlling the
group of UAVs
Amelin Konstantin
[email protected]
Scientific supervisor: Dr. Granichin O.N., Faculty of Mathematics
and Mechanics, Saint-Petersburg State University
The modern calculation model can be presented as mobile device, which have
different sensors (e. g., video or photo camera, GPS, temperature and pressure
sensors, etc.) and are able to “communicate'' with each other. They collect the
information and then hand over information on the supercomputer which does the
finite calculations. Mobile devices, gathering the information at the same time can
filter it, i.e., mark features and separate data on different topics (such as separate
files with coordinates from photo files).
In this paper such a model is illustrated on real example of multi-agent system
for the group of unmanned aerial vehicles (UAVs). The aspects discussed above
are manifested in the creation of such a system. If anybody uses traditional UAVs
with operators and systems of transmit / receive data then usually automated system
failed to work properly on a huge stream of data, which should also save and pass
it to the computer for processing. For the reverse of UAVs flow control the results
cannot be obtained in real time.
The main idea of this work is to create network of UAVs. This is a group of
UAV-agents, which are able to communicate and exchange data on two level:
between each other and with base (ground) stations. Base stations receive data
from a group of UAVs, filter it and send to a supercomputer. The group of UAVs
solves the current task which can be changed by supercomputer or operator through
the network of the base stations. There are no strong tasks for the single UAV and
this principle allows increasing the overall performance for the group which has
a general task.
Three layers of UAV's control system are considered in details to realize this
approach. For example the common group's task of monitoring of wide land is
studied in the focus of the maximizing the flight duration through common usage
possibilities of thermal updrafts. For the precise detection of the thermal updraft's
center the simultaneous perturbation stochastic approximation (SPSA) type
algorithm is proposed.
66
Consensus problem in multi-agent load balancing
system
Amelina Natalia
[email protected]
Scientific supervisor: Dr. Fradkov A.L., Faculty of Mathematics
and Mechanics, Saint-Petersburg State University
Distributed coordination in networks of dynamic agents has attracted numerous
researchers in recent years. It is mostly due to broad applications of multi-agent
systems in many areas, formation control, flocking, cooperative control of
unmanned air vehicles (UAVs), attitude alignment of clusters of satellites, and
others. Many of these problems can be reformulated in terms of achieving consensus
in multi-agent systems. The solutions of such problems are much more complicated
in the practical application. On the one hand, it is because of imperfect information
exchange, which is, moreover, usually measured with noise. On the other hand, it
is due to the effects of quantization effect common to all digital systems.
In this paper we consider the problem of load balancing in decentralized
stochastic dynamic network with noisy information about the current load and
productivity, changing set of communication links and delay. Such problem is
important for control of production networks, multiprocessor or multicomputer
networks, etc.
Load balancing problem is reformulated as consensus problem in noisy model
with switched topology. For solving this problem we suggested to use the stochastic
approximation type algorithm. The performance of the system is evaluated both
analytically and by simulation.
The simulation results for decentralized load balancing computing system
demonstrated good performance of the algorithm.
To analyze closed loop system we propose to use method of continuous models
(ODE approach or Derevitskii-Fradkov-Ljung (DFL)-scheme). The usage of this
method let us to reduce the computation load. The simulation results evaluating
performance of the system and comparison with its deterministic model are
presented.
67
The appearance of chaos in discrete dynamical systems
Brandt Christopher
[email protected]
Scientific supervisor: Prof. Dr. Fiedlers B., Faculty of Mathematics,
Freie University Berlin, Germany
We are going to give a mathematical definition for chaos in discrete dynamical
systems, followed by a famous example of a system exhibiting chaos called 'Smales
Horseshoe'. The aim is to give a brief overview of dynamical phenomena which
are connected to chaos, namely homoclinic tangencies and cascades of period
doubling bifurcations.
68
Frequency estimates of oscillation period for nonlinear
discrete-time systems
Fyodorov Alexey
[email protected]
Scientific supervisor: Prof. Dr. Leonov G.A., Department of
Applied Cybernetics, Faculty of Mathematics and Mechanics,
Discrete-time dynamical systems play a very important role in the modern
applied mathematics [1-3, 4]. They provide a convenient tool for describing control
systems and deliver a simple models of the chaotic dynamics [4, 5].
Systems having a complex chaotic behavior are considered in the present
work. The problem of estimating the cycles periods for systems with one timeindependent differentiable non-linearity and for systems with one periodical nonlinearity is solved. The received estimates are applied to classical one-dimensional
systems and to phase-locked loops that hold a prominent place in electronics and
in computer architecture.
References
1. G. Leonov, S. Seledzhi, A. Fyodorov, O. Kuznetsova, E. Kudryashova.
Analytical-numerical analysis methods of control system // Proceedings of the
23rd IAR Workshop on Advanced Control and Diagnosis, pp. 287 – 291. 2008,
Coventry, UK.
2. G. Leonov, S. Seledzhi, O. Kuznetsova, A. Fyodorov, E. Kudryashova. Periodical
oscillations of control systems. Analytical and numerical approach. // Proceedings
of 6th Vienna International Conference on Mathematical Modeling, pp. 416 – 427.
2009, Vienna, Austria.
3. G. Leonov, A. Fyodorov. Frequency estimates of oscillation period for discretetime systems. // Proceedings of 3rd IEEE Multi-conference on Systems and Control
MSC, pp. 26 – 27. 2009, Saint-Petersburg, Russia.
4. Hassan K. Khalil. Nonlinear Systems. Prentice Hall, 2002.
5. Li T.Y., Yorke J.A. // American Mathematical Monthly 82, 985 – 992, 1975.
69
Decentralized adaptive synchronization of dynamical
networks with white noise disturbances
Grigoriev Grigory
[email protected]
Scientific supervisor: Prof. Fradkov A.L., Department of
Theoretical Cybernetics, Faculty of Mathematics and Mechanics,
An enormous interest is observed recently in control of networks. There
were several researches made in this area during recent years, such as [1, 2],
and others. It is motivated by a broad area of potential applications: formation
control, cooperative control, control of power networks, communication networks,
production networks, etc. Despite a great interest in control of networks, only a
restricted class of them is currently solved. For example, existing papers are dealing
mostly with networks of disturbance-free systems [2] or availability of the whole
state vector for measurement as well as appearance of control in all equations for
all nodes is assumed in decentralized stability and synchronization problems [1].
Thanks to growth of the area application of the results achieved for the networks
of dynamical systems, a lot of new problems arise, such as taking into account
uncertainties and a switching structure of the bond graph, partial decomposition
of a control, nonlinear dynamic of the local subsystem (agent) and uncertainties
in measures. In the previous works synchronization algorithms for networks
with bounded disturbances have been developed, but powerful passivity based
approaches are not developed for adaptive synchronization problems for systems
with white-noise disturbances.
Speed gradient algorithm is used to develop the adaptation algorithms in this
case. In contrast to the disturbance-free case, convergence of trajectories of the
leader and the agents with white-noise disturbances is not possible. To avoid
instability of the overall system, adaptation algorithms are regularized by means
of negative parametric feedback, similarly to [3].
References
1. Jinhu Lu, Guanrong Chen. // IEEE Trans. Autom.Control, V. 50, N. 6, 2005.
2. Dzhunusov I.A., Fradkov A.L. // Automation and Remote Control, 2009, V.70,
(7), pp.1190˝U1205.
3. Fradkov A.L., Razuvaeva I.V., Grigoriev G.K. Passification Based Adaptive
Control Under Coordinate-Parametric White Noise Disturbances. Prepr. 8th IFAC
Symposium NOLCOS 2010, Bologna, 2010. pp. 659-664.
70
Upper Hausdorff dimension bounds for invariant sets of
dynamical systems on Hilbert manifold
Ignatovich Amina
[email protected]
Scientific supervisor: Prof. Reitmann V., Department of Applied
Cybernetics, Faculty of Mathematics and Mechanics, SaintPetersburg State University
In this talk we offer a proof of some upper bounds of the Hausdorff dimension
of invariant sets of dynamical systems on infinite-dimensional manifolds. In the
first part of the talk we provide basic concepts of the theory of infinite dimensional
manifolds. We introduce the following constructions: the concept of a differentiable
mapping, the covariant derivative, parallel transport, the exponential of the
derivative in the finite and infinite cases. In the second part of the talk we present
the basic of dimension theory, define the outer measure and the Hausdorff dimension
and show some auxiliary theorems. The concept of singular values is introduced.
This concept is needed to formulate the main result, i.e. the theorem on the upper
bound of the dimension of an invariant set of a map. We also formulate a theorem on
upper bounds of the Hausdorff dimension of the invariant set of a vector field.
71
Construction of exact solutions of differential inclusions
Kasatkina Olga
[email protected]
Scientific supervisor: Dr. Shamin R., Department of Differential
Equations and Mathematical Physics, Faculty of Science, Peoples’
Friendship University of Russia
Finding exact solutions for nonlinear differential equations is possible only
in exceptional cases. As a rule, in order to find solutions it is necessary to use
approached numerical methods [1]. As a result the numerical solution satisfies the
initial equation only with some residual. If the application of numerical methods
has appeared successful then the received residual will appear small. It is possible
to formalize a problem by means of differential inclusions on a finding of the
approximate solution with residual not surpassing the set size. Thus the finding of
the approximate solution can be treated as a finding of the selector of differential
inclusions.
Such replacement of the initial equation by differential inclusion can have clear
physical sense. Really, if the right parts have certain physical sense, for example,
external force, as it is known, any physical sizes have certain accuracy. Hence, in
this case the change of the right parts on a small residual is always justified from
the physical point of view. On the other hand, it is possible to present the found
numerical solution, as a rule, in a closed form. And often initial equation has such
form that for the received approximate solution it is possible to find residual also
in a final form. As a result we find not only the selector of the differential equation
in a final form, but also the exact solution of the differential equation with the
corrected right part.
On the first step, on the example of an ordinary differential equation with an
algebraic right part the 4th order Runge-Kutta method has been applied for finding
the approached solution. Its error and residual have been calculated.
In the second step, on an example of the equation of nonlinear transfer has been
calculated it’s residual, and by means of the received data a graph of maxx∈[0;2π]|R(t,x)|
has been constructed on the set [t0,t1].
The third step deals with modeling of “killer waves” within the limits of the
exact equations of hydrodynamics. It also looks at the prospect of finding the exact
solution with the corrected right part in equations which describe the dynamics of
superficial waves of an ideal liquid.
References
1. Shamin R.V. Numerical experiments in modeling of surface waves in ocean.
M.: Science, p. 133 (2008).
72
Existence of quadratic Lyapunov function for the
systems with several nonlinear blocks
Lipkovich Mikhail
[email protected]
Theoretical Cybernetics, Mathematics and Mechanics Faculty,
In this paper a problem of finding necessary and sufficient conditions for the
existence of a quadratic Lyapunov function for the control system with multiple
inputs of a special form is considered. Inputs are nonlinear functions of outputs,
which graphs are located in the first and third quadrants.
It is well-known that existence of Lyapunov function with special properties
implies stability. Also, it is known that stability of system involves existence
of Lyapunov function, but there is no rule how to find it. That is why a typical
approach to stability study is to find Lyapunov function from a certain class, e.g.
quadratic Lyapunov function. For functions from this class it is necessary to find
only one Hermitian matrix. So, it is convenient to have conditions of existence of
quadratic functions.
In this paper it is shown that standard circle frequency domain criterion is
necessary and sufficient for existence of a quadratic Lyapunov function for the
case of the nonlinearities with graphs in the first and third quadrants.
The proven conditions can show, how wide a class of stable system, which have
a quadratic Lyapunov function. In such systems tending of solutions to the zero
can be estimated by exponents. Coefficients in this estimate can be easily founded
through eigenvalues of matrix of Lyapunov function.
The same problem for systems with one input was solved by V.A.Yakubovich
in 70th. In common case, it isn't possible to solve this problem for systems with
multiple nonlinear inputs, because such conditions request lossless of the S
procedure for functions of appropriate form. But in the case considered in this
paper, when inputs are located in the first and third quadrants, S-procedure isn't
lossless. The theorem about it was proved and considered in this paper.
73
Algebraic approximation of global attractors of discrete
dynamical systems
Malykh Artiom
[email protected]
Scientific supervisor: Prof. Dr. Reitmann V., Department of
Algebraic sets are a useful tool for the approximation of global
attractors. There was proposed a method by Foias and Temam [1] which allows
to construct algebraic approximations with given precision for a large class of
continuous dynamical systems. In this talk we describe a modification of the FoiasTemam method for discrete dynamical systems.
References
1. Foias C., Temam M. // SIAM J. Math. Anal. 25 (5), p. 1269-1302, (1994).
74
Trajectory steering problem for an autonomous
wheeled robot
Melnikov Alexander
[email protected]
Scientific supervisor: Prof. Dr. Fradkov A.L., Theoretical
In the present paper we apply the result obtained in [1] to the problem of
trajectory tracking for non-holonomic wheeled robot. The linearized vehicle models
considered below are analogous to those proposed by Ackermann et al. Unlike
the Ackermann models, we consider the case of unicycle-like robots analogous
to those considered.
The essence of the invariance problem is to design a controller that provide
the closed-loop system to be stable with some of its outputs independent on
the exogenous input (signal invariance) or system parameters (parametric
invariance).
The conditions providing invariance are well known nowadays. Nevertheless,
even for the linear case no constructive description of all controllers providing the
signal invariance seems to be known.
As an example of practically important signal invariance problem, we consider
the trajectory tracking problem for autonomous wheeled robot. The problems of
trajectory tracking for such vehicles are investigated in a great deal of papers [2, 3]
most of which exploit methods of nonlinear control. In the vicinity of the desired
path the vehicle motion may be described adequately with the linearized Ackermann
model [4], and thus may be investigated by means of linear control theory
techniques. Unlike the referenced works, we consider the case of three wheeled
unicycle-like robot. We reduce the trajectory steering problem in question to the
signal invariance problem, the ”external signal” to suppress being the curvature of
the steered line and the input to be invariant is the steering error (distance to the
desired path). The performance of the obtained controllers for robust trajectory
steering is modeled using both MATLAB simulations and experiments with real
robot assembled of the LEGO Mindstorms NXT constructor.
References
1. Yakubovich V.A. // Doklady Mathematics. 1995. V.52. N1. 1995, pp.151–
154.
2. Soetano D., Lapierre L., Pascoal A. // Proceedings of IEEE CDC 2003, pp.
1765-1770.
3. Theory of Robot Control, C. Canudas de Wit, B. Siciliano, and G. Bastin (Eds.),
Springer Verlag London, 1996.
4. J. Ackermann et al. Robust Control Systems with Uncertain Physical Parameters,
Springer Yerlag, London, 1994.
75
Solvability of some class of boundary value problems for
differential-difference equations
Neverova Daria
[email protected]
Scientific supervisor: Dr. Skubachevskii A.L., Department of
Differential Equations and Mathematical Physics, Faculty of
Science, Peoples’ Friendship University of Russia
Let Q3n be a bounded domain with boundary ∂Q 2C∞. We introduce the
operator
RQ = PQ R I Q ,
where IQ is the operator of extension by zero in n \Q, PQ is the operator of restriction
to Q, operator R is defined by the following formula
Ru ( x) =
∑ a u ( x + h).
h∈
h
Here  is a finite set of vectors h2n with integer coordinates, ah are complex
numbers.
We consider the following problem:
−∆u ( x) + RQ u ( x) = f ( x)
( x ∈ Q) (1)
with homogeneous Dirichlet conditions
u |∂Q = 0, (2)
where
f ( x) ∈ C σ (Q ), (0 < σ < 1). We assume that operator RQ+ RQ* is nonnegative, then we have proved existence
and uniqueness of classic solution u2 C2+σ(Q̅ ) of the problem.
References
1. Skubachevskii A.L. // Elliptic functional differential equations and applications.
Basel–Boston–Berlin, 1997.
2. Gilbarg D., Trudinger N. // Elliptic partial differential equations of second order,
2nd ed. Berlin-Heidelberg-New York: Springer, 1983.
76
Synchronization of power systems
Pchelkina Irina
[email protected]
Scientific supervisor: Dr. Fradkov A.L. Mathematics and
Mechanics Faculty Saint-Petersburg State University
Feature of most power system lies in the fact that manufacturing processes
cause significant variations and jumps of consumed power in generators. There
are objects where failures in electricity lead to disastrous effects; therefore it is
necessary to ensure uninterrupted power supply. The solution of this problem is
to synchronize generators into unified system whose components work in parallel
regime. Although to date some solutions of synchronization task have been offered,
development of simple and robust controllers for electrical generators remains an
important issue. Also there is an interest to solve the problem with incomplete
measurement of the system variables. In addition it is desirable that the control
algorithm would be simple and not containing systems parameters.
Often, control algorithms for several objects are a generalization of the methods
proposed for single-node systems [1, 2]. Thus in the first stage of this work the
model of single electrical generator from [3] was considered. In this model there
are parameters characterizing the losses in the lines. For this model the energylike function was written. The control goal was to achieve a minimum value of
this function. If the value of the generator EMF (electromotive force) equals its
equilibrium, then other system variables converge to their equilibria, as a energylike function – to its minimum. Having used the PI controller to control the EMF
the control goal was achieved.
Here we study the generalization of the considered single-node model to the
case of several generators [3]. The control goal is to ensure the synchronization
of the system. A nonlinear EMF control algorithm is proposed and the coefficients
providing synchronization are determined. The efficiency of the proposed algorithm
is illustrated by numerical simulation with parameters from [3] for a system of
two and ten generators.
References
1. Pogromsky A.Yu., Fradkov A.L., Hill D.J. Passivity based damping of power
system oscillations / in Proc. Of the 35th Conf. On Decision and Control. Japan,
pp. 3876-3881, (1996).
2. Dib W. et al. // IEEE Trans. on Automatic Control, vol. 54, no. 9, pp. 2179-2185,
(1999).
3. Ortega R. et al. // IEEE Trans. on Automatic Control, vol. 50, no. 1, pp. 60-75,
(2005).
77
Control of the creeping three-linked robot
Plotnikov Sergei
[email protected]
The problem of an independent control of the plane three-linked robot
locomotion on a horizontal plane is considered. The dry friction forces interact
between the three-linked robot and the mounting plane, that submit to Coulomb's
law. The algorithm for a robot control is based on the sequence of the fast and
slow locomotion phases idea, which is offered by an academician of RAS Felix
Chernousko [1]. The suggested algorithm has some differences from Chernousko’s
approach. The areas of preference for the proposed algorithm and for the
Chernousko’s algorithm are outlined.
The control vehicle was made from Lego Mindstorms NXT set-up. The robot
has three links and no wheels, therefore it is a mechanical analog of snakes and
other creeping animals. The central part of the robot is the NXT block. On the
sides of it there are two motors which ensure the robot locomotion. In the article
it is shown how mechanical system can move in the longitudinal direction by
using the internal control moments. The displacements and locomotion speed are
estimated. The control algorithm is developed on NXT OSEK software platform.
Experimental results are demonstrated.
References
1. Chernousko F.L. State Estimation for Dynamic Systems — Boca Raton: CRC
Press, 1994. - 304 p.
78
Taken’s time delay embedding theorem for dynamical
systems on infinite-dimensional manifolds
Popov Sergey
[email protected]
Applied Cybernetics, Faculty of Mathematics & Mechanics, SaintPetersburg State University
In 1981 Takens proved a theorem that allows the phase space of dynamical
systems evolving on smooth finite-dimensional manifolds to be reconstructed from
an appropriate time series. Later this result was generalized by Robinson [1] to
the case of dynamical systems on an arbitrary Hilbert space. Our talk considers
dynamical systems defined on infinite-dimensional manifolds. We provide a certain
generalization of the result of Robinson for such dynamical systems. Moreover,
unlike Robinson’s paper where the results were obtained by the embedding theorem
for infinite-dimensional sets due to Hunt & Kaloshin [2], our result makes use of
an embedding theorem for infinite-dimensional manifolds due to Okon [3]. All
results are stated using the notion of prevalence.
References
1. Robinson J.C. // Nonlinearity № 18 pp. 2135-2143 (2005).
2. Hunt B.R. and Kaloshin V.Yu. // Nonlinearity № 12, pp. 1263-1275 (1999).
3. Okon T. // Arch. Math. № 78 pp. 36-42 (2002).
79
Energy based and sampled-data control of the cartpendulum system
Seifullaev Ruslan
[email protected]
Scientific supervisor: Dr. Fradkov A.L., Department of Theoretical
Cybernetics, Mathematics and Mechanics Faculty, SaintPetersburg State University
The possibilities of implementation for energy-based control of nonlinear
oscillations are studied. This approach is based on the speed gradient method [1,
2] and energy-based goal functions. The approach is analysed by example of cartpendulum system control. As a result of the research the algorithm of a swing of
the pendulum on the cart is obtained. Vertical stabilization algorithm is based on
sampled-data control of linear systems under uncertain sampling with the known
upper bound on the sampling intervals [3]. Working capacity of algorithms is
confirmed by simulating in MATLAB Simulink.
Paper also contains the description of cart-pendulum laboratory set-ups
controlled by program block LEGO Mindstorms NXT and their use in education
and research. Every set-up has a unique construction and characteristic singularities
concerning operational mechanism and measuring systems. The control algorithms
are carried out in MATLAB by using the package RWTH Mindstorms NXT
(Aachen Path, www.mindstorms.rwth-aachen.de) or nxtOsek (http://lejos-osek.
sourceforge.net). In the first case (RWTH) there is a possibility to control the robot
microcontroller directly from the computer. Packages of commands are transferred
to the block NXT while program executing. In the second case (nxtOsek) the
program is executed directly on the microcontroller board. It allows to avoid delays
during the transmission of the data.
References
1. Fradkov A.L. // Remote Control, vol. 3, 1999, pp. 213-229.
2. Fradkov A.L. The Cybernetic Physics: Principles and Examples. Nauka,
2003.
3. Fridman E. // Automatica 46, 2010, pp. 421-427.
80
Adaptive synchronization of networks with nonlinear
delayed interconnections
Selivanov Anton
[email protected]
Synchronization in the networks of dynamical systems has attracted a growing
interest during recent years. It is motivated by a broad area of potential applications:
formation control, cooperative control, control of power networks, communication
networks, production networks, etc. Most of existing works are dealing with full
state feedback and linear interconnections. Such system models are restrictive for
applications. In addition, existing papers consider fully controlled systems, where
the number of controls is equal to the number of the state variables and each control
variable enters the corresponding state equation. The aim of the present work is
to overcome these restrictions. Moreover, all results are formulated for delayed
coupled networks.
Controllers of the systems are decentralized, that is the only information that
is available for the controller of the node is an output of current node. As soon
as the controller doesn’t posses any information about the states/outputs of other
nodes it is natural to suppose that the influences of other nodes are small enough.
Furthermore, the case of unknown system parameters is considered. An adaptive
controller based on the Speed-Gradient Method [1] is synthesized. Sufficient
conditions for synchronization are formulated. Numeric simulations demonstrate
efficiency of proposed controller.
References
1. Fradkov A.L. Cybernetical Physics: From Control of Chaos to Quantum Control.
Springer, Heidelberg, Germany, 2007.
81
Two-phase problem arising from a microwave heating
process in nonhomogeneous material
Serkova Nadezhda
[email protected]
Scientific supervisor: Prof. Dr. Reitmann V, Department of Applied
A process of microwave heating of material is considered in our talk.
Mathematical model of this process consists of Maxwell’s equations and the heat
transfer equation. A case of nonhomogeneity with respect to the Maxwell's equations
is examined. Consequently, electric permittivity and magnetic permeability
functions have piecewise constant type. A theorem of existence of global weak
solution of the problem is given.
The problem is modeled using a numerical method. Changes in the temperature
profile are considered depending on the parameters of electric permittivity
and magnetic permeability on different intervals with respect to the Maxwell's
equations.
82
Lyapunov functions in upper Hausdorff dimension
estimates of cocycle attractors
Slepukhin Alexander
St_Sandro@mail,ru
General upper estimates of the Hausdorff dimension of attractors of dynamical
systems have been derived for the first time by A. Douady and J. Oesterlé in [1].
Later these results were generalized by other authors [2, 3]. For the first time
Lyapunov functions have been introduced into the estimates of Hausdorff dimension
by V.A. Boichenko and G.A. Leonov in [4].
The investigation of non-autonomous differential equations leads to the theory
of cocycles and their attractors, which is briefly introduced in this paper. The aim
of this paper is to give upper Hausdorff dimension estimates for a class of global
cocycle attractors or invariant sets by using the singular values of the linearized
cocycle flow and adapted Lyapunov functions, where the cocycle is generated by
nonautonomous ordinary differential equation.
The main results of this paper are two theorems about upper Hausdorff dimension
estimates of cocycle attractors or invariant sets which include Lyapunov functions.
These results can be looked as generalization of the estimates for attractors or
invariant sets of autonomous systems [4, 5] to cocycle attractors.
The well-known Rössler system with time-dependent coefficients is investigated.
An upper estimate for the Hausdorff dimension of the associated cocycle invariant
set is derived.
Obtained results are mainly published in [6].
References
1. Douady A., Oesterlé J. // Comptes Rendus de l'Académie des Sciences. Série
A, 290, pp. 1135-1138. (1980).
2. Smith R.A. Some applications of Hausdorff dimension inequalities for ordinary
differential equations. // Proceedings of the Royal Society of Edinburg, vol. 140
A, pp. 235-259. (1986).
3. Temam R. Infinite-Dimensional Systems in Mechanics and Physics. Springer,
New York – Berlin, 1988.
4. Boichenko V.A., Leonov G.A., // Acta Applicandae Mathematica, vol. 26, pp.
1-60, 1992.
5. Boichenko V.A., Leonov G.A., Reitmann V. Dimension Theory for Ordinary
Differential Equations. Vieweg-Teubner Verlag, Wiesbaden, 2005.
6. Leonov G.A., Reitmann V., Slepukhin A.S. // Doklady Mathematics, Vol. 84,
No 1., pp. 1-4, 2011.
83
Dirichlet kernel and Lebesgue constants for a certain
type of Hadamard matrices
Stojanoska Irena
[email protected]
Scientific supervisor: Prof. Dr. Malozemov V.N., Department of
Operations Research, Faculty of Mathematics and Mechanics,
The standard discrete Walsh functions, used to perform the Hadamard transform,
are one of the basic objects in discrete harmonic analysis, due to their efficiency in
solving number of tasks in digital signal processing. The aim of this work was to
investigate another powerful tool for signal processing, the less known orthogonal
set of discrete functions PONS, also taking values only ±1, and forming basis of
arbitrary size.
We study the problem of the determination of Lebesgue constants of certain
special types of Hadamard matrices, the rows of which represent the previous
mentioned discrete PONS functions. The properties of the corresponding Dirichlet
kernel are investigated. Relationships are derived between two Dirichlet kernels,
one of which is twice the size of the other. Interesting properties of the Lebesgue
constants were obtained, among which is a formula for recursive calculation of an
arbitrary Lebesgue constant.
References
1. Byrnes J.S., Saffari B., Shapiro H.S. Energy spreading and data compression
using the Prometheus Orthonormal Set // Proc. IEEE DSP Conf. on DSP, Loen,
Norway, 1996.
2. Byrnes J.S. // Applied and Computational Harmonic Analysis, Vol. 2, pp. 261266, 1994.
84
Synchronization of two nonlinear Lurie systems with
delaybased on passification and backstepping
Usik Egor
[email protected]
Scientific supervisr: Prof. Dr. Fradkov A.L., Theoretical
In practical problems of automatic control often arises a problem of designing
the control algorithms of dynamic cascade systems. These systems consist of two
units: an irreducible stabilizable system and an integrator (a chain of integrators).
The system describing the motion of mobile robots, belongs to this type of systems
and the role of the integrator in this case is the rate of the change of the angle.
This problem is solved on the basis of backstepping. The special class of nonlinear
dynamical systems is built from subsystems that radiate out from an irreducible
subsystem that can be stabilized using some other method.
The problem of synchronization of nonlinear affine systems by feedback is so
far well researched and one of the approaches to solve this problem is an approach
based on passive objects [1]. The concept of passivity means that the system satisfies
an integral relation with a functional of the system’s input and output. The task
of stabilizing an object is conducted in two stages. The first phase is the task of
passification of the system, that is the problem of finding a feedback law that makes
the system passive [2]. In the second phase, with certain additional conditions such
as observability, the problem of stabilization of the passive system is solved.
In this paper we solve the problem of synchronization of two nonlinear systems
using the backstepping method, which reduces to the passification problem and
stabilization of cascade systems in the case when the system is described in Lurie
form with a functional uncertainty. This method is applied to two systems describing
the motion of mobile robots with delay. This class of systems was not considered
in earlier passification problems. The approach formulated in this paper is different
from existing approaches of passification cascade systems. Those methods require
complete knowledge of all the parameters of the object and may not be applied to
the systems considered.
References
1. Fradkov A.L. // Autom. Remote Control, vol. 35, no. 12, pp. 1960–1966,
1974.
2. Seron M.M., Hill D.J., Fradkov A.L. Adaptive passification of nonlinear systems
// Proc. 33rd IEEE Conf. on Decision and Control. Orlando, FL. Dec. 1994, pp.
192–195.
85
The sunflower-equation: in search of the global attractor
Vu Xuan Tuyen
[email protected]
Scientific supervisor: Prof. Dr. Fieier B., Faculty of Mathematics,
Free University Berlin
Consider the delay-equation:
r*x''(t)+a*x'(t)+b*sin(x(t-r))=0 , a,b > 1, r> 0
This delay equation describe the motion of the sunflower, where x(t) is the
angle of the plant with the vertical. a, b are positive constants bigger 1. r is the
time lag depending on the geotropic reaction of the sunflower, which is caused by
the auxin concentration in the plant. We want to study the asymptotical behavior
of this delay-equation, therefore we are looking for the global attractor, if it exists.
Furthermore we want to know if the Hopf Bifurcation for the sunflower-equation
using the delay as parameter occurs? For technical details we refer the audience
to the work [1, 2].
References
1. Lizana M. // Journal of Mathematical Analysis and Applications 190,1-11
(1995).
2. Somolinos A.S. // Quarterly Applied Mathematics 35 (1978), 465-477.
86
Illiquidity measure. New empirical approach
Yamshchikov Ivan
[email protected]
Scientific supervisor: Prof. Bordag L.A., Hochschule ZittauGorlitz, Germany
We use the ideas of Lippman and McCall and Hooker and Kohn in order to
build a "comprised" measure of illiquidity that would take into consideration the
time aspect as well as the aspect of price. We demonstrate how crucial both of
these aspects are, yet as far as we know there was no any empirical definition that
could constructively work with both aspects and not compromise on other minor
factors.
We are developing our model in the economical settings of the paper by Tebaldi
and Schwartz. This is a framework of the optimal consumption problem with the
fixed terminating moment. Similar concept and notations are used yet the reasoning
is as general as possible. Our method was inspired by this work, however, it could
be applied for a broader class of cases.
Basing on the empirical data obtained from the real market it is shown how
the new upsilon-measure corresponds to the empirical data. The analysis of the
model is carried out by comparison of the results of its' implementation with the
corresponding results of the models known before. The measures are calculated
for different stocks on the market. Also it is calculated for a fixed quote during the
so-called “illiquidity shock”.
References
1. Acar E., Adams R. and Williams R.// Journal of Asset Management, 2, 2001,
pp. 75 – 83.
2. Bordag L.A. // Lobachevskii Journal of Mathematics, 31(2), 2010, pp. 90 99.
3. Hooker M.A. and Kohn M. An Empirical Measure of Asset Liquidity. Hanover,
NH 03755-3514, 1994.
4. Lippman S.A. and McCall J.J. // The American Economic Review, 76(1), 1986,
pp. 43 – 55.
5. Schwartz E.S. and Tebaldi C. Illiquid Assets and Optimal Portfolio Choice.
NBER Working Paper Series, 2006, 12633.
87
On qualitative characteristics of rogue waves
Yudin Alexander
[email protected]
Scientific supervisor: Prof. Shamin R.V., Shirshov Institute of
Oceanology of the RAS, Moscow, Russia
Waves with extreme amplitude (rogue waves) can arise in the nonlinear
dynamics of the ideal liquid with a free surface. Our aim is to show this effect and
consider qualitative characteristics of these waves:
•
amplitude;
•
energy;
•
impuls.
To solve this problem, we should conduct a high-accuracy calculation on
large intervals of time. This becomes realizable due to properties of the functional
differential equations [1].
References
1. Shamin R.V. // J. Math. Sci. (N.Y.), 160, №5, 537—678 (2009).
88
Smoothness of the value function for the optimal
consumption problem with the presence of a random
income flow
Zhelezov Dmitrii
[email protected]
Scientific supervisor: Prof. Dr. Bordag L.A., Department of
Mathematics/Natural Sciences, University of Applied Sciences
Zittau/Görlitz, Germany
We consider the intertemporal investment and consumption problem with the
presence of the random income. Duffie and Zariphopoulou (1993) [1] proved the
existence and uniqueness of the viscosity solution of the associated HJB equation
for the class of concave functions. Some years later, in 1997, Duffie, Fleming, Soner
and Zariphopoulou [2] proved the smoothness of the viscosity solution in the case
of the HARA utility function and infinite time horizon. The proof of the smoothness
the latter case heavily relies on the reduction of the initial HJB equation to the
ODE. After the reduction the main result stems from the uniform convergence of
the classical solutions of the uniformly elliptic equation of the viscosity solution
that is unique. We provide the similar reduction in the case of the logarithmic utility
function and prove that the value function is twice differentiable as well. As far as
we know this fact was not explicitly addressed before.
References
1. D. Duffie, T. Zariphopoulou. Optimal investment with undiversifiable income
risk. // Mathematical Finance, № 3, pp. 135 - 148, (1993).
2. D. Duffie, W. Fleming, H. M. Soner and T. Zariphopoulou. Hedging in incomplete
markets with HARA utility. // Journal of Economic Dynamics and Control, № 21,
pp. 753 - 782, (1997).
89
D. Solid State Physics
Shape memory effect in microsized samples of ferromagnetic
alloy Ni-Mn-Ga
Akatyeva Christina
[email protected]
Scientific supervisor: Dr. Koledov V.V., Kotelnikov Institute of
Radio-engineering and Electronics of RAS
Since the discovery of giant magnetic-field-induced strains in Ni-Mn-Ga ferromagnetic alloy with the shape memory effect (SME) much of works have been
done with purpose to apply this phenomenon to micromechanics. Unfortunately,
the SME is intrinsically irreversible. Usually, external force biasing or special
procedure of ‘training’ of the alloy for ‘two-way’ SME should be applied. This is
not convenient for microsized samples of the alloy. Recently, the new two-layer
composite scheme is proposed, which allow obtaining of the reversible deformation
using only one-way SME [1]. In the present work we describe the preparation and
study of microsized composites with SME on the base of 50 µm thick Ni-Mn-Ga
Heusler alloy melt spun ribbons (see Fig. 1).
a
b
Fig. 1. Pure SME in melt spun ribbon of Ni-Mn-Ga alloy. Sample is in martensite
(a) and in austenite (b).
The microsized samples preparation and experiments on thermally actuated
SME are achieved in vacuum chamber of FEI Strata 201 FIB device. The sample
size is approximately 10x3x1 µm3. The thicknesses of the layer with SME of the
composite are down to 0.5 µm and less. The experiments on thermal actuation and
prospects of magnetic field control of the new type of actuators are discussed.
References
1. Irzhak A.V., Kalashnikov V.S., Koledov V.V. et al. // Technical Physics Letters.
V. 36, p. 329–332 (2010).
92
The isolated molecular cluster approach and study of
point surface phenomena in TiO2
Andreev Alexey
[email protected]
Scientific supervisor: Dr. Chizhov Yu.V., Department of Photonics,
Faculty of Physics, Saint-Petersburg State University
The properties of point intrinsic defect states on TiO2 surface such as oxygen
vacancies or Ti3+ ions attract great attention since they determine advantages of
titania in various technological applications. The quantum chemistry methods are of
key importance to make clear the physical and chemical properties of such species.
In present work we proposed to apply the isolated molecular cluster approach to
study the point surface phenomena in more detail. Specifically, the reduction of TiO2
nanoparticle by hydrogen adsorption and the consequent adsorption of molecular
oxygen on resulting Ti3+ defect states were investigated. All calculations were performed at density functional theory level. A small isolated molecular stoichiometric
cluster Ti8O16 was used as a model nanoparticle with extended surface.
The calculations show that the atomic hydrogen reacts with O atoms of Ti8O16
and forms stable OH groups without significant activation energy. The OH group
formation is accompanied by appearance of singly occupied 3d-Ti level in the
cluster’s “band gap”. It means that one of the Ti4+ atoms is reduced to Ti3+ active surface point center. The modeling of molecular oxygen adsorption on these
reduced titanium atoms shows that molecular O2 trap an extra electron from the
Ti3+ atom converting the latter into initial Ti4+ state. Meanwhile the 3d-type level
in the cluster’s “band gap” disappears. These features are in agreement with the
main experimental observations on the H plasma reduction of TiO2 nanoparticles
and interaction of reduced TiO2 with molecular oxygen. Our calculations are confirmed by: 1) the EPR spectroscopy data and sample coloring of TiO2 from white
to blue upon atomic hydrogen exposure [1]; 2) the bleaching of reduced TiO2 upon
molecular oxygen exposure and data on optical absorption in NIR region [2].
Thus, the rather new computational approach may be consistently used for
describing the point surfaces phenomena on nanoscaled TiO2. Specifically, that
allows us to simulate the more complex redox reactions at the TiO2 surfaces in
further studies using proposed model.
References
1. Berger T., Diwald O., Knözinger E., Napoli F., Chiesa M., Giamello E. // Chem.
Phys. 2007, 339, 138.
2. Komaguchi K., Maruoka T., Nakano H., Imae I., Ooyama Y., Harima Y. // J.
Phys. Chem. C 2010, 114, 1240.
93
Atomic force microscopy as a method ofсonstructional
materials study
Borygina Klavdiya, Nikolaev Philipp, Ulyanov Pavel,
Senkovskiy Boris
Scientific supervisor: Prof. Adamchuk V.K., Dr. Usachov D.Yu.,
Department of Solid State Electronics, Faculty of Physics, SaintPetersburg State University
Equipment protection of industrial objects requires development and perfecting
of constructional materials diagnostic tools. Metallographic examinations are very
important among the different nondestructive methods of control and diagnostic of
operating equipment constructional materials. Existing standards of optical metallography were developed decades ago and nowadays they need modernization of
either mathematical image processing and instrumentation of researches.
Use of atomic force microscopy (AFM) for nondestructive analysis of constructional materials may become one of the leading directions of development
of standard metallography methods. In comparison with optical microscopy AFM
methods have some advantages. First of all AFM methods have better resolution;
secondly AFM image is three dimensional, which allows to get additional information about microstructure of material.
In this work we present an AFM study of 5 steel grades of different classes,
which are mostly used as constructional materials in oil-processing and petrochemical equipment and comparison of images obtained with instrumentation of
standard optical metallography and AFM. It was shown that both AFM and optical
metallography can give information about microstructure of material but with AFM
is possible to achieve resolution on a nanometer scale. Construction steels surface
preparation methods of optical metallography are also applicable for AFM studies.
Differences in etching rate of different phases, grains in definite crystallographic
directions and grain boundaries give opportunity to determine steel microstructure
via analysis of three dimensional AFM images.
Presented results can serve as a basis for development of new direction of
constructional materials diagnostics which can be called atomic force metallography.
This work was supported by Russian Government resolution 218.
94
Influence of boundary conditions on reflection spectra of
thin films
Chernyy Valeriy
[email protected]
Scientific supervisor: Dr. Grigorieva N.R., Department of
Solid State Physics, Faculty of Physics, Saint-Petersburg State
University
Recently considerably increased an application of thin films in various semiconductors devices. Therefore a development of investigation methods becomes very
urgent. The exciton spectroscopy is a very effective and quite sensitive method of
semiconductors structures. Analysis of reflection spectra allows to get information
about structure under study and watching over influence of exposure. A complicate
structure of thin film reflection spectra cause by interference and size quantum
effect. A task of modeling of a line shape of reflection exciton spectra has not completely decision. Sufficient quantitative coincidence theoretical and experimental
exciton spectra required taking to account additional boundary conditions.
As an object of the modeling was chosen a thin film of the cadmium sulfide.
The surface on which light incident called boundary 1, other surface designation as
boundary 2. The contribution of the boundary 2in reflection spectrum was studied.
The contribution of boundary 2 was estimated from changing of shape of exciton
reflection line with and without dead layer at boundary 2. Modeling was performed
in wide range of thicknesses including thickness where size effects is important
and thickness exceeded the free length.
It was found that the value of contribution of boundary 2 is periodically changed
with film thickness. The contribution of boundary 2 is neutralized for relatively
small thicknesses of the films. This fact can be explain by suppress of the reflected
wave by interference. For tacking to account influence of interference and size
quantum effect the comparison of reflection spectra and the exciton energy spectra
in quantum wall was performed.
95
Hybridization of f- and d-electron states in EuRh2Si2
Chikina Alla
[email protected]
Scientific supervisor: Prof. Dr. Adamchuk V.K. , Department of
Solid State Electronics, Faculty of Physics, Saint-Petersburg State
University
The element europium with its half-filled 4f shell occupies an unique position
among other rare-earth(RE) metals. Europium in different solids can be either
divalent and magnetic, or trivalent and nonmagnetic. Some compounds with an
intermediate valency are also known.
Angle resolved photoemission (ARPES) allows the most direct access to individual 4f states and their interactions with the valence bands: From the intensity
of the individual 4f 5 final-state multiplets in the ARPES spectra the valency may
be determined, while interactions with valence states are reflected by dispersions
of individual multiplet lines. Since in Eu systems the 4f5 final state is degenerate
in energy with the mixed-valent ground state, properties of the latter are directly
monitored in the ARPES spectra.
The purpose of the given work is to calculate band structure and estimate
contribution into anisotropy of the f-d hybridization in ARPES spectra EuRh2Si2.
In the case of Ce[1] and Yb [2] it was possible in the framework of a simple approach to the Periodic Anderson Model (PAM). Application of the model to Eu
systems is not trivial because the model anticipates that like in Ce (or Yb) only
one electron (or one hole, respectively) is involved in the hybridization process
leaving the other 4f electrons unaffected. Therefore it was developed a model of
the hybridization between 4f- and valence states.
As a result the valence band structure of surface and bulk states without
interaction with 4f states was calculated. All bands in the vicinity of 4f states
location were tested for ability of interaction. It was found that linearly dependent
states, which are able to couple to the 4f of the surface, is a Rh (4d) surface state.
Finally, interaction between Rh (4d) surface state and 4f multiplet was calculated
in frameworks of hybridization model. Comparing the results of calculations with
experimental data has been verified the validity of this approach.
References
1. Danzenbächer S., Kucherenko Yu., Heber M., Vyalikh D.V., Molodtsov S.L.,
Servedio V.D.P., and Laubschat C. // Phys. Rev. B №72, 033104 (2005).
2. Vyalikh D.V., Danzenbächer S., Yaresko A.N., Holder M., Kucherenko Yu.,
Laubschat C., Krellner C., Hossain Z., Geibel C., Shi M., Patthey L., and Molodtsov
S.L. // Phys. Rev. Lett. №100, 056402 (2008).
96
Supersonic speed in the disperse environments
Dejnega Marina
[email protected]
Scientific supervisor: Dr. Koltsova I.S., Department of Solid State
Under the "supersonic" speed means the propagation velocity of ultrasonic
waves in the heterogeneous – disperse environments, in excess of the speed in
the matrix.
The search for new advanced materials for the industry, led to the heterogeneous - disperse environment have become the objects of study of modern physics.
In such environments, the physical parameters of the change on the border of the
matrix and disperse phase. By varying the properties of the components disperse
environments can be purposefully obtain new materials with desired parameters.
One of the most important parameters of composites is the bulk modulus, which
is responsible for the deformation of structures, created from composite materials.
Information on the effective module of elasticity of the heterogeneous - disperse
mediums can be obtained by exploring the propagation velocity of ultrasonic
waves in them.
The experiments showed that the propagation velocity of ultrasonic waves in
before percolation areas with higher concentration decreases, in percolation area
reaches its minimum, in post percolation the speed of sound begins to increase, and
at a concentration exceeding 50% of the speed of sound in heterogeneous - disperse
environments exceeds the speed of sound in the matrix. Ultrasonic measurements
of the concentration dependence of the speed of sound in heterogeneous - disperse
media showed that the deformability heterogeneous-disperse systems in before
percolation area the more the deformability of the matrix, and in post percolation
the deformability heterogeneous-disperse systems is less than the deformability
of the matrix.
References
1. Koltsova I.S. Distribution of ultrasonic waves to heterogeneous environments.
- St.-Petersburg, 2007, 245 p.
2. Isakovich M.A, Mandelshtam L.I. Distribution of a sound in micronon-uniform
environments // УФН, 1979. Т.129, №3. p.531-540.
3. Kolesnikov A.E. Ultrasonic measurements. – М: Sovjet Encyclopedia, 1970.
4. Shutilov V.A. The Basis of physics of ultrasound. - L. Publishing house LSU,
1980. 280 p.
97
XPS study of kinetics of graphene hydrogenation
Fedorov Alexander
[email protected]
Scientific supervisor: Prof. Dr. Adamchuk V.K. , Department of
University
Recently graphene has been discussed as a material with highest potential for
post-silicon electronics [1]. The main requirement for graphene to have applications
in electronics is existence of a phase transition from semimetal to semiconductor
or insulator. The most promising route for the realization of this transformation is
through chemical functionalization, such as hydrogenation.
The totally hydrogenated graphene is well known as the “graphane”.
Electronically, graphene is the zero-gap semiconductor and graphane is an insulator
with an energy gap of 3.5 eV [2] which makes it an attractive material for optoelectronics in the UV range. For graphane theory predicts electron localization, a
peculiar midgap state, strong excitation effects and high-Tc superconductivity in
hole-doped graphane.
In this work kinetic properties of the graphene hydrogenation were studied by
means of X-Ray photoelectron spectroscopy (XPS) approach with high energy
resolution, achieved by using the synchrotron radiation source. Graphene was
prepared using chemical vapor deposition technique (CVD) on the Ni(111) thin
film. Gold intercalation approach was used to obtaine quasi-freestanding graphene
and to reduce Ni influence on the hydrogen adsorption process.
Stability of the intermediate states of the hydrogenation process was observed,
which allowed using “step by step” technique for investigation of kinetic process.
By performing long hydrogenation cycle it was shown with XPS that only 25%
of carbon atoms can be bonded with hydrogen. The results of quantitative XPS
data analysis were treated in the frameworks of the Langmuir adsorption theory
to obtained kinetics constants. Low adsorption probability - only 3.5% and high
reflection (85.5%) and stimulated hydrogen desorption (11%) probabilities were
demonstrated.
References
1. Geim A.K. and Novoselov K.S. // Nature Mat., 6, 183 (2007).
2. Richard B., Bjarke J., Louis N., Mie A., Emile R., Marco B., Mattia F., Erik L.,
Alessandro B., Silvano L., Zeljko S., Flemming B., Bjork H., Thomas G. Pedersen,
Philip H. & Liv Hornekær // Nature Mat. 9, 315 (2010).
98
The investigation of routes of the reaction NO + CO +
hν → ½ N2 + CO2 on TiO2 (Hombifine N) under visible
irradiation
Glazkova Nadezda, Nikitin Konstantin
[email protected]
Scientific supervisor: Dr. Mikhaylov R.V., Department of Photonics,
Titanium dioxide is widely used as photocatalyst in environmental catalysis,
because it is highly active in degrading of many organic and inorganic pollutants.
Earlier it had been shown that the photoreaction
CO+NO+hν → N2 + CO2
(1)
on TiO2 (Degussa P-25) under UV (λ < 400 nm) or VIS (λ > 400 nm) irradiation
takes place [1] due to the activity caused by interband electron transitions (UV) or
VIS light absorption by surface and/or bulk structure defects (oxygen vacancies,
Ti3+ ions). The course of the reaction (1) was divided into two stages [1]. The first
stage is characterized by NO photoadsorption (PA) and appearance of N2O in gas,
whereas the second one is distinguished by an increase in N2 pressure up to a half
of the initial NO pressure accompanied by N2O disappearing. CO2 was found to
remain on the surface. The similar behavior of reaction (1) on TiO2 (Hombifine
N) superfine powder was observed.
The aim of the present work was to investigate the routes of intermediate
species formation during the photoreaction (1) on TiO2 (Hombifine N, anatase,
S=320 m2/g) under visible irradiation by means of kinetic mass-spectrometry and
thermo-programmed desorption spectroscopy. The isotope enriched gases 15N18O
and 13C16O as well as 14N16O and 12C16O were used. The emission lines λ = 404 nm
of the high-pressure mercury lamp SVD-120 equipped with a set of glass filters
(LOMO) were used as light source. The experimental technique and procedures
are the same described in [1].
It is found that in the first stage of reaction (1) the PA NO is accompanied by
intensive hetero-exchange of gaseous NO with the TiO2 surface oxygen atoms,
which rate exceeds 1-2 order the PA one. Two channels of PA NO (fast and slow)
are revealed. The fast channel leads to the formation of NOads species, which rapidly
turn into two adsorbed species of N2O. The slow channel provides the accumulation
of strongly bonded NO-species on the TiO2 surface, which react with CO in the
second stage of reaction (1) forming the intermediate N2O and then N2. CO2 formed
in reaction (1) contains the oxygen atoms early belonged to initial NO.
This work was supported by RFBR under grant 09-03-00795-a.
References
1. Lisachenko A.A., Mikhailov R.V., Basov L.L., Shelimov B.N., Che M. // J.
Phys. Chem. C, 2007, v. 111. p. 14440.
99
Synthesis of Co-based Heusler compound on a singlecrystalline silicon
Grebenyuk Georgy, Popov Konstantin
[email protected]
Scientific supervisor: Dr. Pronin I.I., Division of Plasma Physics,
Atomic Physics and Astrophysics, A.F. Ioffe Physical Technical
Institute of the Russian Academy of Sciences
The half-metallic Heusler alloys are of great basic and technological interest
due to their 100% spin polarization of electrons at the Fermi level. They are very
promising for the creation of spintronics devices based on the injection of polarized electrons into semiconductors. In recent years specifically Co2FeSi Heusler
alloy thin films have received considerable attention as a half-metallic ferromagnetic electrode material for magnetic tunnel junctions. It has been shown that the
high-quality thin films of Co2FeSi can be grown on Si (111) by molecular beam
epitaxy [1]. The aim of the present work was to form the ultrathin layer (~2 nm)
of this compound by less expensive method of evaporation of Co and Fe on the
heated Si substrate. The study of the film growth was completed by investigation
of its magnetic properties.
The growth of the film was carried out in UHV by alternate deposition of small
portions of Co (2 Å) and Fe (1 Å) on the Si(100)2x1 surface supported at ∼170°C.
Characterization of the films was performed by high-resolution photoelectron spectroscopy with synchrotron radiation. Their chemical composition and electronic
structure were probed via the sets of Si 2p, Co 3p, Fe 3p and valence-band spectra.
Information about ferromagnetic ordering of the film was obtained in situ using
magnetic linear dichroism in photoemission of Co 3p and Fe 3p electrons. The
spectra were measured for two opposite directions of remanent magnetization.
Deposition of Co and Fe on the Si(100) surface at elevated temperature results
in the growth of Co-Fe-Si alloy islands. The effect of the magnetic linear dichroism
has a threshold nature and arises at the coverage of 12 Å due to the coalescence of
the islands. Further deposition of metals increases the effect both for Co and Fe lines.
As for the chemical composition of the film, it is not stoichiometric for Co2FeSi
and is depleted in silicon. Post-growth annealing of the film at the temperature of
240°С gives rise to formation of the Co2FeSi Heusler alloy and a small decrease
of the film magnetization. Subsequent temperature increase to 275°С leads to
decomposition of the compound and formation of nonmagnetic silicides.
The study was supported by Russian Foundation for Basic Research (Project
no. 10-02-00632) and the Russian-German Laboratory at HZB-BESSY.
References
1. Y. Maeda, K. Hamaya et al. // Appl. Phys. Lett. 97, 192501 (2010).
100
Relaxation of the magnetization near Curie point in
gadolinium
Kamantsev Alexander
[email protected]
Scientific supervisor: Dr. Koledov V.V., Laboratory of Physics of
Magnetic Phenomena, Kotelnikov Institute of Radioengineering
and Electronics of RAS
The research in the field of the new technology of refrigeration at room temperature based on magnetic materials with phase transitions (PT) attracts much attention
last years. In spite of the fact that magnetic PT were investigated theoretically and
experimentally for a long time, at the moment there is no deep understanding of the
question of the kinetic phenomena going on with magnetic PT, which is crucial in
development of this technology. Practically it is very important to known the fundamental physical restrictions on speed of relaxation processes of order parameter
(magnetization) near critical point of PT. Theoretically [1], relaxation processes
near the 2d order PT point are described by Landau-Khalatnikov equation:
dη
∂Ω = −γ
dt
∂η
where η – order parameter, t – time, Ω – thermodynamic potential, γ – kinetic
coefficient.
The aims of present work are the following:
1) To develop the theoretical basement of the experimental method for the
measurement of the time of establishment of the equilibrium value of order parameter after fast heating and cooling of the sample in the form of thin plate near
PT critical temperature.
2) Theoretical study of heat exchange processes between the water coolant and
the plate made of magnetocaloric material in order to estimate the time response
of heating and cooling.
3) To estimate achievable magnitude of power-to-weight ratio of magnetocaloric
refrigerator or thermal pump with working body made of gadolinium.
The experimental method includes measurements of the magnetic susceptibility signal of gadolinium sample in response to sharp change of its temperature
near PT. The gadolinium plate was placed in water flow, at temperature below
the Curie point (Tc = 19°C). The heating jump was ΔТ = 1°С, its duration did not
exceed 15 ms. The response time τ measured in the range of initial temperatures
16 – 19°C. The dependence 1/τ ~ (Тc-Т) is approximately true in accord with
Landau-Khalatnikov equation. The value of constant γ in Landau-Khalatnikov
equation was estimated.
References
1. Landau L.D., Khalatnikov I.M. // Doklady Akademii Nauk SSSR, v. 96, p. 469,
(1954).
101
Model distribution of oscillator strength for X-ray
transitions near and far from the edge
Kan Yelena, Krivosenko Yury
[email protected]
Scientific supervisor: Prof. Dr. Pavlychev A. A., Department of
University
Inner-shell photoemission process can be approximated with two steps model:
core-hole creation σ⊕ and core-hole ionization cross-section σ+. Spectral dependence of core-hole creation cross section in molecules and solids attracts our attention: σ⊕ = σ0⋅(L∗G∗M) where L, G and M denote Lorentzian, Gaussian distributions
and modulation function responsible for spectral redistribution of oscillator strength
for atomic transitions in polyatomic systems, and σ0 is the atomic cross section.
Symbol ∗ implies a convolution. G is responsible for the band width of photon
source; L takes the core-hole decay.
In the work the model distribution (L∗G∗M) (k) is examined near and far from
the ionization threshold.
Firstly, the modulation function is investigated in the vicinity of the shaperesonance. The modulation function is decomposed in the region and it is demonstrated that it can be approximated by the asymmetric Lorentzian distribution:
M(k) ≈ L≈α(k), where α indicates the asymmetry parameter. That results in the
following consequence: experimental photoelectron spectra can be fitted by the
convolution of Gaussian, asymmetric Lorentzian and symmetric one. Such a fitting is made for 4eg shape resonance in experimental S 2p absorption spectrum.
What is more, it is found that the convolution of the first two distributions can
be in some cases approximated by a single asymmetric Lorentzian with effective
width and asymmetric parameter. Application of this approximation permits to
simplify analysis decently.
Secondly, a formula expressing (L∗M) is derived within the assumption that
Lorentzian distribution is narrow enough for the modulation function to be well
represented by a parabola (which means far beyond the shape-resonance region,
where such decomposition is invalid):
(4 − π)W 2
. ( M * L)(k ) ≈ M (k ) + M ''(k )
16π
The result is compared with the M(ρ∗L), where ρ is absolute value of the
reflection coefficient, k is photoelectron wavevector. It is obtained that (M∗L)(ρ)
can be substituted by M(ρ∗L), when W (Lorenztian distribution FWHM), second
derivative of M over ρ and ρk’are low enough.
102
The absorption spectra of reduced TiO2 nanocluster:
TDDFT study
Khaustov Sergei
[email protected]
Scientific supervisor: Dr. Chizhov Yu.V., Department of Photonics,
Oxygen vacancies and Ti3+ ions are the two most common point defects on the
surface of TiO2 resulted from reduction process. These species determine advantages of titania in various technological and industrial applications. Specifically,
they are a primary reason for the formation of visible-light/NIR-active TiO2 [1].
Previously the absorption spectra of reduced titania nanoparticles with single
oxygen vacancy were investigated using isolated molecular cluster approach [2].
In present work we simulated the absorption spectra of TiO2 nanoparticles reduced
by atomic hydrogen.
All calculations were performed at time-depended density functional theory
(TDDFT) level. A small isolated molecular stoichiometric Ti8O16 cluster was used
as a model nanoparticle. The Ti8O14(OH)2 clusters may be regarded as a suitable
model of reduced clusters. Only nine specified isomers from total 120 possible
Ti8O14(OH)2 clusters were considered in this study.
The calculations show that two H atoms react with oxygen of Ti8O16 and form
two stable OH groups. This reaction is accompanied by appearance of two singly
occupied 3d-Ti levels in the middle of cluster’s “band gap”. The summarized
simulated absorption spectrum of nine Ti8O14(OH)2 isomers has two bands in
visible-light region at 2.75 and 1.64 eV.
The obtained results are in agreement with the main experimental observations
on the H plasma reduction of TiO2 nanoparticles. Specifically, our calculations are
confirmed by the Ti3+ species formation and sample coloring of TiO2 nanoparticles
from white to blue upon atomic hydrogen exposure [3]. Furthermore, the results of
present work are very similar to that obtained for oxygen deficient Ti8O15 clusters.
Thus, we suppose that defects usually related to oxygen vacancies at the TiO2
surface and Ti3+ states have the same nature.
References
1. Kuznetsov N., Serpone N. // J. Phys. Chem. 2009, 113, 15110-15123.
2. Andreev A. // Book of Abstracts, Student conference «Physics and Progress»,
2009. P. 44.
3. Berger T.,Diwald O., Knözinger E., Napoli F., Chiesa M., Giamello E. // Chem.
Phys. 2007, 339, 138.
103
Monte-Carlo simulation of small molecules photo
adsorption on wide band gap solids
Khramtsou Yauheni
[email protected]
Scientific supervisor: Prof. Ryabchuk V.K., Department of
Photonics, Faculty of Physics, St. Petersburg State University
The most typical method used for kinetic studies in heterogeneous photocatalysis is the method of formal chemical kinetics where the particles and quasi-particles
(such as molecules, charge photocarriers, defects and so on) are characterized by
their concentrations. The strong demerit of such approach is the impossibility to
distinguish surface and bulk processes [1].
Different approach is based on the models considering bulk and surface concentrations of photogenerated charge carriers which can be found by solving the
continuity equation applying various boundary conditions [2]. However, this approach allows to find a solution for simplified systems only (such as infinite plate
or semi-infinite single crystal, that is single-dimensional systems).
In present study we apply the approach for modeling surface photostimulated
molecular process involving charge carriers photogenerated in the bulk of the solid
particle, surface active centers (surface defects) and molecules of gaseous or liquid
phases, based on direct Monte-Carlo simulation. In our model the positions of
photogenerated charge carriers in each time moment is assumed to be appointed.
Significant issue in the model is that interaction of molecules with surface defect
occurs only after charge carrier trapping by the defect [3]. This interaction leads to
significant decrease of trapping cross-section for recombination of charge carrier
of opposite sign with trapped charge carrier localized in adsorption complex. The
discussed model considers such processes as photogeneration of charge carriers,
their random walk and trapping by defect states (trapping by surface defects results
in formation of adsorption complex). The model can be used to analyze the effect
of the size and shape of the particle on the efficiency of photostimulated processes
such as photocoloration and photostimulated adsorption.
Detailed discussion of the obtained results of model simulation will be given
during presentation.
References
1. Emeline A.V., Kataeva G.V., Sharemet’eva N.V., Ryabchuk V.K. // Vestnik
SPbGU, Ser. 4, Iss. 4, p. 153 (2004). (in Russian).
2. Emeline A.V., Ryabchuk V.K., Serpone N. // J. Phys. Chem. B, v. 103, p. 1316
(1999).
3. Artemiev Yu.M., Ryabchuk V.K. / Introduction in Heterogeneous Photocatalysis.
SPbGU, SPb, 303 pp (1999) (in Russian).
104
Spin-orbit splitting of surface alloy Bi/Ag on Mo(100)
Klimovskikh Ilya
[email protected]
Scientific supervisor: Prof. Dr. Shikin A.M., Department of Solid
State Electronics, Faculty of Physics, Saint-Petersburg State
University
Effects of spin splitting of electronic states attract increasing attention of investigators in recent years, as they have important significance in rapidly developing
spintronics. One of the ways to observe this splitting is analysis of systems with
spin-orbit interaction. In the bulk of solids with central symmetry electronic states
of opposite spin orientation are degenerate. But degeneracy can be lifted, if inversion symmetry is broken, for example at surface.
There is particular interest to investigate surface alloys, in which value of
spin polarization can reach very high magnitude. In work [1] there was carried
out analysis of effects of spin orbit splitting surface states of surface alloy Bi/
Ag(111). Authors showed that spin splitting of unprecedented magnitude leads
to high value of in-plane potential gradient, while classical model of spin orbit
coupling at surface (Rashba-Bychkof model) includes potential gradient along the
surface normal. Consideration of both gradients results in out-of-plane rotation of
spin polarizatioFn and high value of spin splitting. In work [2] authors established
that spin splitting of quantum and interface states in several monolayers of Ag
is determined by spin orbit interaction in substrate. Moreover, value of splitting
increase with atomic number of substrate.
This paper is dedicated to analysis of electronic states of system, consisting of
2 monolayers of Ag and monolayer of Bi on Mo(100). System was investigated
by angle- and spin- resolved photoelectron spectroscopy with the application of
synchrotron radiation. Experimental electronic structure and spin resolved spectra
show that quantum and interface states are spin-split, and value of splitting is quite
high, in spite of weak influence of substrate (atomic number z= 42). Also, from the
data obtained one can make conclusion about dependence of spin orbit splitting of
electronic states on value of in-plane momentum. Different factors influencing on
the spin structure of the Bi/Ag surface alloys on Mo(100) will be analysed.
References
1. Ast C.R. et al. // Phys. Rev. Lett. 98, 186807 (2007).
2. Shikin A.M. et al.// SSP 52, 1121 (2010).
105
Admittance spectroscopy of near-surface quantumdimensional semiconductor structures
Kolevatov Ilya
[email protected]
Scientific supervisor: Prof. Dr. Vyvenko O.F., Department of Solid
University
During the last decade admittance spectroscopy (AS) have been widely used
to investigate electronic states of quantum dimensional structures (QDS) such as
quantum wells and quantum dots [1-2]. The classic variant of this technique assumes the refilling of the electronic states with charge carriers fill electronic states
in the absence of Schottky diode current when a reverse bias voltage is applied.
That restricts the application of the technique only for the QDS located relatively
deep under the sample surface at a distance of the order of the thickness of the
diode space charge region. The latter value is typically of about 1 um for moderately doped semiconductors while many of used devices contains QDS buried at a
shallow depth of about 100-200 nm. In this case electronic states can be occupied
only at sufficiently high forward bias voltages when the current flowing through
the Schottky diode is not negligible and thus, the theoretical description of the
classical AS can’t be applied for interpreting of the data.
In this work, we applied the model [3] originally developed for the investigation
of surface states for the experimental data treatment obtained on QDS. Theoretical
expression for the calculation of energy distribution of the electronic from the measurement data of differential capacitance and conductivity were derived. The results
of experimental investigation of energy levels of dislocation networks produced
by direct wafer bonding by means of AS and deep-level transient spectroscopy
were presented and discussed.
References
1. Zubkov V.I. Spektroskopiya admitansa poluprovodnikovyh nanogeterostruktur.
Dr. Thesis. LETI, SPb, 2007.
2. Brunkov P.N. Emkostnaya spektroskopiya elektronnyh sostoyanii v geterostrukturah s kvantovymi yamami i kvantovymi tochkami. Dr. Thesis. FTI im. Ioffe, SPb.
2007.
3. Werner J., Ploog K, Queisser H.J. // Phys. Rev. Let. V. 57 No. 8, 1986.
106
X-ray spectroscopy investigation of thin films Al2O3
synthesized on porous SiO2 by ALD
Konashuk Alecsei
[email protected]
Scientific supervisor: Prof. Filatova E.O., Department of Solid
University
Modern microelectronics industry develops today on the way of transistor
density maximization. It is recognized, however, that device physics is not the
first limiting factor to the continued performance improvement for systems. The
challenge will be to carry electric power in integrated circuits. It is caused by
capacitance associated with metallic conductors, so the impact of signal delay
will undoubtedly increase as we move into the nanometer regime. Also increasing
frequencies and higher densities lead to a dramatic increase in power consumption. This consumption is related with leakage current between wires and dynamic
dissipation caused by wire capacitance [1].
The most effective solving of these problems is to introduce pores into the
interlayer dielectric to achieve dielectric constant below than 2. The most optimal
material for this aim is silicon dioxide, because the old technology just is based
on the use of this material.
Nevertheless when the porous SiO2 is used as substrate to prepare thin films a
number of questions are appeared and special investigations are required. The most
controversial issues are: i) whether the form on the substrate surface is the film or
porous will be filled by Al2O3; ii) how does it depend on the synthesis conditions
and characteristics of the porosity of the substrate, such as pore size and their distribution on the surface; iii) what is its microstructure in case of film, how does it
depend on film thickness and depth; iiii) is film amorphous or crystalline? If there
are crystallization signs, what is ratio of tetrahedral and octahedral coordinations,
whether this ratio could be controlled by variation in porosity characteristics; iiiii)
is there interlayer between substrate and film.
The present work will be focused on the investigation of thin Al2O3 films with
different thicknesses synthesized by Atomic Layer Deposition on porous silicon
dioxide substrates. The basic methods of the investigations are X-ray reflectometry
and X-ray Photoelectron Spectroscopy.
References
1. Maex K., Baklanov M.R., Shamiryan D., Lacopi F., Brongersma S.H. et al. //
J. Appl. Phys. 93, 8793 (2003).
107
Inner-shell photoemission from caged molecules СО@
C60, N2@C60
Kondratyev Sergey
[email protected]
Scientific supervisor: Prof. Pavlychev A.A., Department of Solid
University
Electronic and atomic properties of fullerenes have attracted much attention
over the years. The great interest is connected to the study of photoionization and
photoemission from atoms and molecules caged in fullerene. Spectral dependence
of inner-shell photoionization cross-section is determined by the interference of
the primary and scattered photoelectron waves. Within the quasiatomic approach
the interferential function is determined by the reflection and scattering matrixes
and can be calculated analytically in the case of the molecule fixed in the center
of fullerene approximated by the zero-range potential. The next approximation
implies using of the vibration-dependent-fixed-nuclei (VDFN) model to describe
vibrational effects on the interference on photoelectron waves in CO and N2 molecules confined in C60. The aim of the present work is to evaluate the effect of
zero-point molecular motion on the backscattering amplitudes using the effective
quadratic displacement as parameter that dominates this effect. The influence of
inelastic photoelectron scattering on the carbon atoms on inner-shell photoionization is also examined and discussed.
References
1. Weaver J.H., Poirier D.M. // Solid state Physics, vol 48.
2. Xu Y.B., Tan M.Q. and Becker U. // Phys r. l. vol 76, num. 19.
108
Recoil effect as a probe of interaction between a
monolayer matter andunderlying substrate
Krivosenko Yury
[email protected]
Scientific supervisor: Prof. Dr. Pavlychev A.A., Department of
University
Photoelectron recoil effect results from the pulse imparted by the outgoing
photoelectron to the residual ion and consequently plays significant role in forming photoelectron spectra. The effect increasing with the increase of the ambient
photon energy (and hence the photoelectron kinetic energy) can cause a shift of the
centroid of a spectrum to several tenth of eV towards higher binding energies and
therefore cannot be neglected while interpreting experimental data or constructing
theoretical models.
In this work we investigate recoil effect accompanying photoionization of
monolayer matter on a substrate with carbon atoms monolayer being the example
of the former. The excitation of the local vibrational modes is considered and translational recoil of the whole ionized system is neglected. From that point of view the
effect causes excitation of vibrational motion of the ionized C+ atom in the effective
potential responsible for the interaction between the monolayer and the substrate,
which can be approximated by the harmonic potential. Such excitations are easily
described by changing the r‑representation (coordinate) to p‑representation (pulse)
[1], which transforms Hamiltonian H(r, iћ∇r) to H(iћ∇p, p). In such a representation the vibrational wavefunction of the carbon atom in the field of the substrate
does not almost differ from that one in the coordinate representation and can be
written in the following form:
1
1/ +
/ 0
" /
/
where Hv is the Hermite polynomial of the v‑th order and α denotes a constant of
transition from pulses to dimensionless magnitudes: α2=ћωμ.
The populations of the vibrational states are calculated as a square of scalar
production of the wavefunctions ψv(p) and ψv'(p+Δp), where the recoil pulse is
denoted by Δp. Hence, the populations coincide with ordinary Franck-Condon
factors calculated in the p‑space. The described procedure is performed for carbonon-susbtrate system ionized by the X-rays. The computational results (i.e. model
spectra) are compared with the experimental report [2] and sufficient agreement
is detected.
References
1. Kukk E. et al. // Phys. Rev. Lett., 95 (2005) 133001.
2. Takata Y. et. al. // Phys. Rev. B, 75 (2007) 233404.
109
Investigation of thin Ni films on Ge substrate
Kungurtsev Eugene, Rogushkin Kirill
[email protected]
Scientific supervisor: Prof. Dr. Yafyasov A.M., Department of
University
Much attention is devoted to the investigation of metal-semiconductor and
metal-oxide-semiconductor systems today, more one is paid to study of structures
with nickel films and nanoparticles. The reason of so much interest is the observation of giant magnetoresistance in nickel nanostructures, as well as several other
characteristics that are associated with the influence of an intermediate layer
between the nickel and the semiconductor [1]. In most cases, silicon is used as
a semiconductor, but in recent years the interest in the study of germanium as a
material alternative to silicon has significantly increased due to the transition to
technologies 45/32 nm in future. The advantage of germanium is high carrier
mobility compared to silicon . The electron mobility in germanium is nearly three
times higher than in silicon, and the value of mobility for the holes is highest one
among all known semiconductor materials. This paper considers the thin nickel
films formed electrochemically on a p-Ge substrate.
We measured the dependence of the surface conductivity (σ) of germanium
electrode from the electrode potential (φ), σ-φ measuring was carried by using
field-effect in electrolyte methods, which strongly differs from field effect in MIS.
The dependence of the conductivity of the germanium sample from the time of
electrodeposition of nickel on its surface was measured. We also measured the
temperature dependence of the conductivity of the germanium sample and the
germanium sample with a thin nickel film on its surface.
σ-φ measuring was carried on variable signal with frequency 23 Hz. Surface
potential values was varying from -0,9 V to -0,6 V. A nickel film was deposited
on the cleaned surface of p-Ge with resistance 1 om∙cm and 5 om∙cm. The thickness of the nickel film was in the range between 40 nm and 200 nm. The sample
temperature was varied from 120 to 450 K.
We developed techniques of Ni deposition on Ge substrate, the data obtained
from measurements of the temperature dependence of conductivity indicate the
difficult structure of the boundary Ge-Ni. The assumption was made about the
mechanism of growth of Ni films on the Ge substrate based on the results.
References
1. Edelman I.S., Patrin G.S., Velikanov D.A., Chernichenko A.V., Turpanov I.A.,
Bondarenko G.V. // JETP Letters, Vol. 87, ed. 5, p. 310 – 313.
110
Origin of dislocation-related luminescence
Loshachenko Anton.
[email protected]
Scientific supervisor: Dr. Vyvenko O.F., Department of Solid
University
One of the main problems of modern silicon industry is the fabrication of
efficient Si-based light-emitting devices, which could be integrated in an existing technology and work on a wavelength compatible with the optical fiber. The
dislocation – related luminescence (DRL) of D1-line (1.54 nm) is a proper object
for a solution of the above task.
For the first time DRL was observed in the plastically deformed silicon crystal
more than 30 years ago [1]. Despite of the huge amount of the followed investigations the nature of DRL remains unexplained. The matter is that the introduction of
dislocations is accompanied with the generation of point-like defects and the point
defects reactions can give rise to the creation of dislocations. Thus, it is very difficult
to separate which of two mentioned kind of defects is responsible for DRL.
The aim of the presented work was to vary the dislocation structure and the
point defect content in Si wafers implanted by oxygen by subsequent injection
of equal amount of vacancies and self-interstitials using annealing in chlorine
atmosphere and to find the correlation between the defect structure, luminescent
and electrophysical properties
Transmission electron microscopy investigation showed that some of the
samples annealed at particular conditions did not contain extended dislocations
while demonstrated an intense DRL. On the other hand, the presence of point-like
defects was established by the deep level spectroscopy measurements that revealed
energy levels in silicon band gap that have similar positions in all of the samples.
This facts rule out the commonly accepted suggestion that DRL is related to the
extended 60 degree and/or screw dislocations and indicate that point defects or
their complexes are responsible for DRL [2].
References
1. Drozdov N., Patrin A. and Tkachev V. // JETP Lett. 23, 597 (1976).
2. Farvacque J-L and Franois P 2001// Phys. Stat. Sol. B 223 635–648.
111
Study of structure of nanostructured Ni-Ti alloy with
shape memory effect for medical application and its
application in modern dentistry
Mazaev Pavel, Petrov Alexey, Kalashnikov Vladimir,
Gizatullin Ramil, Koledov Victor
[email protected]
Scientific supervisor: Prof. Kraposhin V.S., Department of Material
Science in Mechanical Engineering, Faculty of Materials and
Technology, Bauman Moscow State Technical University
Nowadays materials used for the manufacture of implants are not compatible with living tissue and pushed out of the body, necessitating replacement.
Nanostructured alloy Ni-Ti, due to its biocompatibility with living tissue and
mechanical compatibility with bone tissue, is the most promising material for the
manufactureof implants, in particular, dental [1-3].
An alloy Ni49,8Ti50,2 in the form of bars of various diameters and lengths,
processed by three different methods: equal-channel angular pressing (ECAP), a
standart method for semi-products and "technological forging". ECAP method is
suitable to make nanostructures, but the distribution of the grain size is appeared to
be nonuniform through samples' section and the proportion of amorphous structure
is obtained, which leads to a process of softening of the material. In the case of
the standard methods semi-products average grain size is equal to 0.5 microns,
but due to the dislocation structure functional properties of these sample as high
as the properties of samples after ECAP. After the process of forging structure
with an average thickness of 100 nm plates and high density of dislocations were
formed.
On the basis of the improved alloy Ni-Ti with shape memory effect “NANODENT” has developed new types of implants: DI (to replace the teeth removed)
and TRI (to enrich tooth and to attach it to the jaw bone). The surface of such
implants is covered with layer of diamond-like carbon in order to ensure high
biocompatibility. Also the new treatment procedure proposed includes the injection into the jaw bone tissue of the mixture of powdered porous NiTi with the new
nanostructured biomaterials Hydrooxyappatite or CollapAN-gel. They resulting
tissue will not be resorbed for long time.
References
1. Brailovski V., Prokoshkin S., Terriault P, Trochu F. Shape Memory Alloys:
Fundamentals Modeling and Applications, ETS Publ., Montreal, Canada, 2003, 851.
2. Gunter V. et al. Titanium nickelide. Medical Supplies of the new generation.
Tomsk, Moscow-MIC, 2006, 296.
3. Gizatullin R. Treatment of chronic destructive forms of periodontitis, a combination of porous TiNi with osteoplastic drug “CollapAn-gel". The collection
"Biocompatible shape memory materials and new technologies in dentistry",
2006.
112
Luminescence in InGaAs/GaAs quantum wells
Morozova Polina
[email protected]
Scientific supervisor: Davidov V.G., Department of Fotonics,
Semi-conductors heterostructures with InGaAs/GaAs quantum wells possess
a great number of interesting optical properties, in particular high efficiency of
interaction exiton subsystem with light. There are two most informative methods
for studying these structures. They are a research of reflexion and luminescence
spectra. As a whole, the method of researching structures by registration of luminescence spectra concedes in accuracy to a method of researching spectra of reflexion. Because between the moment in which we excite any condition in quantum
well and a moment in which it is highlighted, inwardnesses of exiton subsystem
can strongly changed , in particular thanks to processes of energy relaxation. But
radiating recombination (luminescence) at excitation by the laser beam has more
degrees of freedom. Hence, allows to receive more information about energy
spectrum of the investigated sample. For minimize effect of energy relaxation we
used a method of a resonant luminescence.
In this article we explore luminescence spectra of samples on the basis of
InGaAs/GaAs solid solutions with three quantum wells. The luminescence spectra
of two identical parts on structure of one sample P566 have been received. The
diffraction lattice has been put on a substrate of one of parts of the sample by a
method of ionic lithography. The second part has been left without changes.
Our installation make possible a registration and measurement of a resonant
photoluminescence and reflexion spectra near exitons resonances.
In our paper we present the energy picture for samples with corroded and
original substrates in 3D format .We observe a number of effects. In particular,
price to the order of intensity between contours of a resonant and not resonant
photoluminescence, presence of stoks and antistoks components in spectra of a
resonant photoluminescence, failures in a low-frequency contours of a luminescence
at excitation of high-frequency conditions, presence of non-uniform recession of
wings of a contour of a resonant luminescence (a nonlinear luminescence).
In the presented work we show a possibility of registration and representation
of spectra of resonant photoluminescence for high-quality samples with a set of
quantum wells InGaAs/GaAs in a three-dimensional format. Spectra and efficiency
of a photoluminescence appear essentially depending of fluctuations and structure
of solid solutions, thickness of quantum wells, deformations on heteroborders and
a surface of the sample.
113
Single crystal W-probe for STM: formation, structure
and physico-chemical characteristics
Nesterova Мaria
[email protected]
Scientific supervisor: Dr. Bozhko S.I., Institute of Solid State
Physics, Chernogolovka, Russia
Since discovery of STM in 1982 it becomes one of the powerful techniques in
contemporary nanotechnology. Mostly, information acquired in STM experiment
is determined by properties of the STM tip apex. About 90% of tunneling current
is collecting by a tip terminated single atom. Thus further progress in STM also
includes development of probes with unique physical properties. The main problem we were addressed to in our work was formation of tungsten STM tip apex
both single atom and nanoparticle terminated. This would result in possibility to
fabricate probes with predominant physical properties.
A common procedure of tip apex formation consists on electrochemical etching
of W bar in 2M NaOH solution [1]. Electrochemical etching resulted in formation
of a narrow neck which breaks when a weight of W bar part below of the neck exceeds its strength. Loading experiments were performed to simulate the neck break.
Fig.1 (left panel) represents stress and strain curves acquired from neck shaped W
crystals before and during electrochemical etching. When loading is accompanied
by electrochemical etching fracture of both poly and single neck shaped crystals
considerably exceeds one without etching. We suppose that etching continuously
renew surface of the neck and, as a result, complicate creation of defects involved
in deformation of crystal.
Fig. 1. Left: stress and strain curves normalized by the area of neck cross-section. Central:
SEM image of STM tip apex produced from W single crystal. Right: STM image of Si(111)7x7
surface, acquired using W single crystal probe, Vb=-1,4 V, It=0,06 nA.
Fig. 1 (central panel) represents SEM image of sharp W single crystal tip. The
STM image of Si(111)7x7 surface (Fig. 1, right panel) provides an example of
atomically resolved STM imaging using single crystal W tips.
References
1. 1. J.P. Ibe, P.P. Bey, Jr.S.L. Brandow et al. // J. Vac. Sci. Technol. A., Vol. 8, No.4, Jul./
Aug. 1990.
114
The investigation of interaction of N2O and CO on VIS
irradiated TiO2 (Hombifine N) surface
Nikitin Konstantin, Glazkova Nadezda
[email protected]
Scientific supervisor: Dr. Mikhaylov R.V., Department of Photonics,
Titanium dioxide (TiO2) is widely used for photoelectric and photocatalytic conversion of energy radiation in the UV spectral region. Earlier [1] it had been shown
that by using intrinsic defect (oxygen vacancies, Ti3+ ions) the “self-sensitization”
of TiO2 in visible region can be obtained. Really the photoreaction CO+NO+hν
→ N2 + CO2 (1) on nanostructured TiO2 (Degussa P-25) under UV (λ < 400 nm)
as well as VIS (λ > 400 nm) irradiation takes place [1]. The course of the reaction
(1) was divided into two stages [1] depending on participation of photogenerated
electron or hole centers. The first stage is characterized by NO photoadsorption
and appearance of N2O in gas, whereas the second one is characterized by N2O
reduction to N2. CO2 was found to remain on the surface. The similar behavior of
reaction (1) on nanostructured TiO2 (Hombifine N) was observed, but in this case
the intermediate N2O remains on the surface.
The aim of the present work was to investigate the role of photogenerated electrons and holes in interaction of N2O and CO on TiO2 (Hombifine N, anatase, mean
particle size d = 6 nm) under visible irradiation. The kinetic mass-spectrometry and
thermo-programmed desorption (TPD) spectroscopy were applied.
High purity gases N2O and 13C16O were used. The emission line λ = 404 nm
of the high-pressure mercury lamp SVD-120 equipped with a set of glass filters
(LOMO) was used as light source. The experimental technique and procedures
are the same described in [1].
It is found that N2O rapidly adsorbs on TiO2 surface forming a set of weakly
bonded species. The irradiation in N2O causes the additional adsorption and redistribution in adsorbed layer resulting in occupation of most bonded ones, meanwhile
no N2 appears in gaseous. The irradiation in mixture N2O+CO is accompanied by
N2 appearance similarly to that observed in the second stage of reaction (1), while
CO2 remains on the surface. Peak of CO2 appearing in subsequent TPD obeys to
the second-order kinetic of desorption and differs from peaks of molecular CO2
species. The ratio of formed N2 and CO2 is established.
This work was supported by RFBR under grant 09-03-00795-a.
References
1. Lisachenko A.A., Mikhailov R.V., Basov L.L., Shelimov B.N., Che M. // J.
Phys. Chem. C, 2007, v. 111. p. 14440.
115
Study of the thermomechanical properties of
nanostructured Ni-Ti alloy with shape memory effect for
medical application
Petrov Alexey, Mazaev Pavel, Kalashnikov Vladimir, Gizatulin
Ramil, Koledov Victor
[email protected]
Scientific supervisor: Dr. Kraposhin V.S., Department of material
science, Faculty of Machine building technology, Bauman Moscow
State Technical University
One of the important problems of technology is the development of new materials. The solution of this problem is not only connected with the production of the
material. It is also connected with the perspectives of new applications of Ni-Ti
alloy with shape memory effect due to its high termomechanical properties. Even
materials developed especially for research find their applications for creation of
mechanical systems with desired properties [1-4].
Ni49,8Ti50,2 alloy with shape memory effect was chosen for studying. The
samples represent three different thermomecanical treatments: equal channel
angular pressing, standard technology for bulk materials and forging technology.
By using three-point bending method the primary hysteresis curves of the phase
transformation under variable loads are obtained. These curves contain information about characteristics of the phase transition and functional properties. The
functional inflexability and energy capacity are proposed as new general characteristics of the material.
Using energy capacity and functional inflexability, it became possible to defy
the material that demonstrates the highest functional characteristics. As the studied
alloy has a medical application, the most preferred material for the implant is the
sample after ECAP, possessing high recoverable strain (about 6-7%) while reversible stress is about 1200 MPa. But ECAP is proposed to be not very effective method
of nanostructurization because of non contolable process of recristalization during
the processing and big size of blank. In other case the best functional properties
has sample after the forging process, due to its high general characteristics such as
energy capacity and functional inflexibility. Further more this method more.
References
1. Brailovski V., Prokoshkin S., Terriault P., Trochu F. Shape Memory Alloys:
Fundamentals Modeling and Applications, ETS Publ., Montreal, Canada, 2003. 851 p.
2. Gunther V. Nickelide titanium. Medical Supplies of the new generation,
Moscow-MIC, Tomsk, Russia, 2006. – 296 p.
3. Gunther V., Dambaev G., Sysoletin P. Medical materials and implants with
shape memory. – Tomsk: Tomsk State University, Russia, 1998. - 488 p.
116
The velocity and absorption coefficient of ultrasound
waves in suspensions of starch
Polukhina Anastasia
[email protected]
Scientific supervisor: Dr. Koltsova I.S., Department of Solid State
Suspensions are widely used in various fields of science and technology. Exploring their acoustic parameters such as absorption coefficient, the speed
of ultrasonic waves, etc. - we can obtain information on structural changes of suspended matter phase transitions, chemical reactions and energy exchange processes
occurring between the matrix and the dispersed phase. To this end, the complex was
carried out studies on the concentration dependence of the velocity of ultrasonic
waves and the absorption coefficient in areas with irregular and porous structure
of the suspension, namely in the suspension of starch particles. The investigated
heterogeneous system consists of a matrix in which randomly weighed isolated
from each other by particles of starch, differing in size. To describe the dynamic
processes in a structurally inhomogeneous material involved in several models
including the model of micro-environments Mandelstam. When the distance between the particles exceeds their size rmn (rmn»2R) and the number of particles at
the wavelength is large enough so that the propagation of acoustic waves can be
characterized by environment effective parameters: the effective density and effective compressibility, which can be calculated from the concentration dependence
of the velocity in suspensions. The main attention was paid to the measurement of
the absorption coefficient of ultrasonic waves. Studies have shown that the most
effective way to study the dispersion of porous particles is a method of measuring
the absorption coefficient of ultrasonic waves. References
1. Koltsova I. S., Mysun M., Dyatlova E.N. // Propagation of ultrasonic waves
in suspensions, 17-th International Congress of Acoustics, Rome, September 2-7,
(2001).
2. Koltsova I.S., Deinega M.A., Polukhina A.S. // The absorption of ultrasonic
waves in suspensions of porous particles, Collection of works XX session of the
Acoustical Society. Moscow, p.106, (2008).
3. Polukhina A.S. // Loss of acoustic energy in the porous particles, Proceedings
of the youth scientific conference “Physics and Progress”. St.-Petersburg, p. 187,
(2008).
117
Intercalation of Al as a method of formation of
quasifreestanding graphene and modification of
electronic structure in the required direction
Popova Anna
[email protected]
University
Investigations of graphene monolayer have attracted enormous interest in recent
years due to unusual electro-physical properties of this material (linear “photonlike” dispersion of electron states near the Fermi level in the region of the K-point
of the Brillouin zone) and possibility of graphene using as a basic element in future
nanoelectronics and spintronics [1, 2].
At present time one of the main problems of investigation of graphene is a search
of large-scale synthesis of graphene on different substrates and analysis of electronic
structure modification due to interaction of graphene with an underlying substrate.
So, it is very important to purposefully modify the electronic structure of graphene
on top of different substrate. One of the variants is an interaction of graphene with
metals of different nature and controlled modification of the electronic structure
under intercalation of these metals underneath of graphene.
In the present work processes of Al intercalation underneath of graphene, synthesized on top of thin layers of Ni (111), modification of electronic structure of
this system at different stages of experiment and nature of interaction of graphene
with Al were studied and analyzed. Investigation was carried out by methods of
angle-resolved photoelectron spectroscopy (for study of dispersion dependences
of occupied states in the valence band), photoelectron spectroscopy of core levels
(for study of possibility of charge transfer and photoelectron intensity of C, Ni, Al
peaks) and NEXAFS (for study of structure of unoccupied states). It was showed
that the electronic structure of graphene, synthesized on top of Ni (111), with a
subsequent intercalation of Al, is a similar to the electronic structure of quasifreestanding graphene (i.e. a graphene with a week interaction with a substrate), but a
small energy gap near the Fermi level in the region of the K-point of the Brillouin
zone exists. Moreover it was observed that alloying of intercalated Al metal with
Ni substrate with a formation of Ni3Al alloy takes place.
References
1. Geim A.K., Novoselov K.S. // Nature Mat. 6, 183 (2007).
2. Novoselov K.S., Geim A.K., Morozov S.V., Jiang D., Katsnelson M.I.,
Grigorieva I.V., Dubonos S.V., Firsov A.A. // Nature 438, 197 (2005).
118
Conductance calculation of quantum network
elementary units
Prokhorov Yury
[email protected]
Scientific supervisor: Dr. Yafyasov A.M., Goncharov L.I.,
Department of Solid State Electronics, Faculty of Physics, SaintPetersburg State University
Development of nanotechnologies make possible to create electronic devises
with characteristic sizes comparable with de-Broil charge carrier wavelength.
One of the ways to treat such devises is to use quantum networks: two-dimension
or quasi-two-dimension structure on the semiconductor surface that consists of
scattering centers connected by quantum wires. In order to describe transport
characteristics of such systems one have to take into account wave nature of charge
carriers. In practical case, however, it’s necessary to turn from quantum-mechanical
values (wave functions, scattering matrices) to measurable physical magnitudes
(currents and voltage). It can be done by applying generalized Landauer-Buttiker
theory of quasi-one-dimension conductance.
The aim of the present work is to show how quantum interferential effects can
influence on the current magnitude in the system and show possibility of detection
channel of incoming charge carriers flow.
In present work two types of quantum network units are discussed: filter
(transparent for incoming electrons with certain characteristics) and splitter (sorts
incoming electrons depending on incoming spectral channel). In order to calculate
currents and conductivity of the different combinations of this elements generalized
Landauer-Buttiker theory have been used. Carried out calculations have shown:
1. Influence of quantum interferential effects on current flow through the
system.
2. Possibility of creating of some quantum network elementary units.
References
1. Kawabata A. // Rep. Prog. Phys. 70 (2007) 219-254 (stacks.iop.org/
RoPP/70/219).
2. Гончаров Л.И., Яфясов А.М. // Вестник, СПб: Издательство С.Петербургского университета, 2011, серия 4, вып. 3, с. 27-32.
119
Bragg reflection of light from 1D photonic crystals and
dynamical diffraction theory
Romanenko Konstantin
[email protected]
Scientific supervisor: Dr. Sel’kin A.V., Department of Solid State
On the basis of the analytical dynamical diffraction theory, a theoretical study
is made of mechanisms of Bragg reflection spectrum formation for the case of
one-dimensional (1D) photonic crystals (PhC). The applicability area of the
dynamical theory is estimated by comparison of the analytical calculations with
the numerical results of the full electrodynamic computations making use of the
transfer matrix technique.
In the present work, we discuss the dynamical theory approach to describe Bragg
reflection of s- and p-polarized electromagnetic plane waves when reflection of
light occurs from a 1D PhC plate possessing the dielectric function harmonically
varying in space along the normal to the lateral surface of the plate. The model
discussed is of principal interest because it is closely associated with the previously
performed theoretical and experimental studies [1, 2] of opal-like PhCs and allows
one to understand in detail why the dynamical diffraction theory can be used in
the case of PhC with relatively high dielectric contrast as well.
The main purpose of our study is to determine the limits of applicability of the
analytical (dynamical) diffraction theory, namely, to find as few periods as possible which provide a rather good numerical agreement between the results of the
analytical and full-electrodynamic calculations of the reflectance spectra.
It was surprising to find that the analytical theory describes well the spectra at
any thickness of the PhC plate, even though the thickness is a part of the spatial
period of the dielectric function. True, this is the case only at the boundary conditions that have to correspond to appropriate phases of the Fourier amplitudes in
the spatial Fourier expansion of the complex-valued permittivity. These phases are
unambiguously determined by spatial positions of the front and rear plane surfaces
of the 1D PhC plate.
This work was supported by the Saint Petersburg State University Development
Program under Scientific Research No. 11.37.23.2011.
References
1. Bazhenova A.G., Sel’kin A.V., Menshikova A.J, Shevchenko N.N. // Solid State
Physics, v. 49, № 11, p. 2010 (2007).
2. Fedotov V.G., Sel’kin A.V. // Proc. of 19th Int. Symp. “Nanostructures: Physics
and Technology,Ekaterinburg, June 20-25, 2011, 141-142 (2011).
120
Anomalous shift of Bragg reflection peak in 3D photonic
crystals
Rukhlov Nikita
[email protected]
Scientific supervisor: Prof. Sel’kin A.V., Department of Solid State
A number of bright diffractive optical phenomena caused by strong modification
of the energy spectrum of photons inside a spatially periodic solid state structure
can be observed due to the interaction between the electromagnetic field and such
a structure, if periodicity scale is comparable to the wavelength of light. These
structures which have recently become the attractors of practical interest are called
photonic crystals.
According to the usual Bragg formulae, with increasing the angle of incidence θ
a blue shift of the reflection peak occurs in reflection spectra. However, as we have
observed in our experiments, the spectra of some samples apparently demonstrate
the opposite, red, shift of the reflection peak when the incidence angle increases,
which is in contrast with the standard Bragg equation.
Fig. 1. The reflection spectra at different angles of incidence θ of light.
A possible explanation for the phenomenon observed is that a strong diffraction
of light from photonic crystal planes inclined to the reflecting lateral ones takes
place in the case of corrugated surface when the conservation low for tangent
component of the wave vector does not hold.
This work was supported by the Saint Petersburg State University
Development Program under Scientific Research No. 11.37.23.2011.
121
The overview of ultrasonic studies of the meltingfreezing phase transitions for substances in porous
matrices
Shaforostov Eugene
[email protected]
Scientific supervisor: Dr. Borisov B.F., Department of Solid State
Low-dimensional systems are characterized by so-called size effects that
have the diversity of manifestations. In particular, these effects manifest itself in
changing parameters of different phase transitions especially the melting–freezing
processes.
The report presents the overview of studies of the melting–freezing processes
of various substances in confined geometry. In our case, these substances represent
matters embedded in bulk porous silicate matrices. These matters include fusible
metals (mercury, gallium and indium), organic liquids (decane), water, segnetoelectric NaNo2 and segnetoelastic LiCsSO4.
Bulk blocks of macro-porous (average pore diameter d ~100÷200 nm) and
micro-porous (d ~4÷8 nm) glass, synthetic opal (d ~15÷30 nm) and MCM-41
molecular sieves (d ~2÷6 nm) were used as matrices.
The composites were produced from above-listed matrices filled with appropriate matter. The temperature dependences of velocity and attenuation coefficient
of ultrasound waves (USW) were measured in these composites. The standard
acoustic phase–pulse method was used.
These analyses were completed in quantum acoustics and ultrasonic spectroscopy laboratory in the department of Solid-State Physics in Saint-Petersburg State
University in recent years.
All the studied materials showed some general regularities:
1. The shift of the phase transition to low temperatures (which is inversely
proportional to the pore size) in small confined particles compared to that in bulk
matter.
2. The noticeable hysteresis of melting and freezing with clear asymmetry of
cooling and warming branches.
3. The almost jump crystallization process.
4. The blurring of the melting process with fixed temperature of its offset, which
does not depend on thermal history.
The machinery of these features exhibition is discussed.
References
1. Molz E. // Phys. Rev. B, v.48, № 9, p. 5741-5750, (1993).
2. Borisov B.F., Charnaya E.V. et all. // Phys. Rev. B, v.58, № 9, p. 5329-5335,
(1998).
122
An electron irradiation of short-term powerful beams
effect on surface morphology of the materials LiF, Al
Soskin Aleksey
[email protected]
Scientific supervisor: Prof. Dr. Vladimirov G.G., Department of
University
Interaction of short-term powerful beams of particles (photons, electrons, ions)
with the constructional materials is of a huge interest both from theoretical and
practical point of views. Knowledge of properties’ behavior is necessary both for
analysis of particles’ effect and in connection with feather creation of new functional
materials and for characteristics’ necessary changes.
The single crystals LiF and Al were taken as samples. They were irradiated by
short-term powerful beams of electrons with power 1÷150 J and impulse duration
less then 70 ns.
A LiF specimen surface was received by slip. There were revealed many considerable changes on the irradiated field of the surface.
In the core of the irradiated place one can not see straight order. Although
moving to distal end of the probe we can see that the surface is formed from rightrectangle “plates”. The plates are separated from each over by formations which
can be considered as micro fissures. It’s important that approaching the distal end
of the probe the plates’ size gets bigger. On the border field between irradiated
and non-irradiated areas on the surface there are large-scale features. Their shape
seems to reflect LiF lattice’s peculiarities.
It can be supposed that in this case the power of electron beams was close to
the one to destruct the sample.
Al samples. Analyzing AFM data there was revealed a tendency that a few
parameters depend upon quantity after of electron’ “strike”. While plotting a
hispogram where an abscissa shows a height of a surface roughness and ordinate
shows a quantity of the dots from this height, the following tendency of a parameter
(asymmetry coefficient of a peak, Ssk) was revealed.
The Table presents Ssk parameter data for an image 10х10 µm (for the images
of other sizes the tendency of a parameter’s reduction after irradiation keeps on).
Al
Before
impulse
After 1
impulse
After 1
impulse
After 5
impulse
After 5
impulse
After 15
impulse
After 15
impulse
1.674
1.030
0.746
1.001
0.858
1.306
0.474
It can be supposed that during irradiation an upper layer warms up so it provides
mobility, protuberances become more similar-shaped
123
Ferroelastic phase transition in LiCsSO4/MCM-41
nanocomposite
Stolbova Alevtina
[email protected]
A great deal of attention has been recently focused on features of nanostrutured
composites because of their importance for both fundamental and applied physics. A
promising kind of nanocomposites consists of porous matrices loaded with various
substances: metals, semiconductors, ferroelectrics, liquid crystals and others.
Acoustic studies of a nanocomposite consisted of MCM-41 molecular sieves
with nanoparticles of ferroelastic LiCsSO4 within pores were carried out. The ferroelastic phase transition in such system was found from critical anomaly in the
velocity of shear acoustic wave. The transition was shifted to low-temperatures
by about 6 К compared to that in bulk LiCsSO4. The decrease of the transition
temperature can be treated on the base of the Landau phenomenological model
for size-effects in small particles. The absence of thermal hysteresis and reversible behavior of the shear wave velocity near the phase transition confirm that the
transition remains of the second order as in bulk. The dependence of the relative
change of velocity for the longitudinal ultrasonic wave was measured. At 197 K
a small local minimum was observed. However, its value does not exceed the
limits of experimental error. Further studies are required to clarify the nature of
this phenomenon.
The experiments on nanocomposites with LiCsSO4 inclusion showed that
acoustic technique is a very useful tool for studying ferroelastic phase transitions
under nanoconfinement.
References
1. Borisov B.F., Charnaya E.V., Baryshnikov S.V., Pirozerskii A.L., Bugaev A.S.,
Tien C., Lee M.K., Michel D. // Phys. Lett. A 375, (2010) 183.
2. Charnaya E.V., Borisov B.F, Baryshnikov S.V., Pirozerskii A.L., Cheng Tien,
Lee M.K. , Michel D. Ferroelastic phase transition in nanostructured LiCsSO4 . //
European Meeting on Ferroelectricity, June 26 to July 1, 2011, Bordeaux, France,
Conference Proceedings, Oral 5C-4O.
124
Photoinduced adsorboluminescence in Mn:Zn2SiO4
phosphor
Timoshenko Artem.
[email protected]
Scientific supervisor: Prof. Ryabchuk V.K., Department of
Photonics, Faculty of Physics, Saint-Petersburg State University
Discovery of the effect of photoinduced adsorboluminescence opened new
opportunities for in-depth investigations of the direct interaction of molecules
with photoinduced surface centers. The very first experimental observation of the
effect was reported by N.S. Andreev and V.A. Kotelnikov [1]. They detected a
short-time flash in the visible spectral range initiated by post-adsorption of H2 on
pre-irradiated BeO and MgO, as well as by post-adsorption of CH4 and H2O on
photoactivated surface of Al2O3.
The aim of this study was to explore the spectral characteristics of the photoinduced adsorboluminescence caused by post-adsorption of hydrogen on zinc
orthosilicate doped with manganese. Presumably, post-adsorption of molecular
hydrogen takes place on photoinduced hole centers on the surface of Mn:Zn2SiO4
initiating photoinduced adsorboluminescence. The emission spectrum of photoinduced adsorboluminescence which matched the emission spectrum of cathodeluminescence of the phosphor (the band maximum at 520 nm), was registered. This
emission is associated with the recombination of free electrons with manganese
ions Mn3+.
The detailed discussion of the experimental details and proposed mechanism
will be given during the presentation.
References
1. Andreev N.S., Kotelnikov V.A. // Kinetika I Kataliz, v. 15, № 6, p. 1612
(1974).
125
The “closed-channel” property of extended current
S-matrix of junction
Tsurikov Davyd
[email protected]
Scientific supervisor: Dr. Yafyasov A.M., Department of Solid
University
Quantum network is theoretical model of a device, which is suitable for modern
semiconductor nanotechnology. It consists of
quantum dots (junctions) connected with each
:
other by quantum wires (branches).
For calculation of electron currents through
*
a junction (Fig. 1) it is necessary to find its
:
extended scattering matrix S [1]. It relates
: *
amplitudes c of waves scattered by the junc*N
:N
tion with amplitudes c of waves incident on
the junction:
Fig. 1. Section of two-dimensional
c+   S + + S+ −   c+ 


c
=
quantum network: Ω – junction,
  = 
    = Sc (1)
S
S
c
c
−−   − 
 −   −+
Ωk – k-th branch, Γk := ∂Ωk∩∂Ω.
Here subscripts “+” and “–” correspond to opened and closed channels
respectively:
c+� := {cm�k | λ km < ε}km , c−� := {cm�k | λ km ≥ ε}km , �=,  (2)
where λ are energies of channels, ε is energy of an electron, superscripts and subscripts are numbers of branches and channels respectively.
In present paper according to the condition of total current conservation for
extended current S-matrix
kl
kl
C := K +1/ 2 SK −1/ 2 , K mn
:= κ km I mn
, κ km := ε − λ km (3)
where I is unit matrix, we derive two properties:

(4)
&
& , &&
& &
L&
& The first is well-known unitary property of the submatrix, which relates opened
channels; the second is property of the submatrix, which relates closed channels.
The obtained result can be useful for the accuracy control during numerical calculations of extended current S-matrix.
References
1. D. E. Tsurikov and A. M. Yafyasov // Vestn. St. Petersb. Univ., Ser. 4: Fiz.,
Khim., No. 1, p. 153 (2010).
126
Calculation of sound speed in artificial opal
Andrey Uskov
[email protected]
Microcellular materials are widely used as catalysts, filters and adsorbents. They
also could be used to investigate properties of materials in confined geometry. For
example, it is possible to investigate properties of phase transitions in liquid metals embedded in porous glasses and artificial opals by measuring dependency of
sound speed on temperature. But the theory which could link elasticity of embedded
material and sound speed is still absent [1, 2]. The aim of this work is calculation
of sound speed in artificial opal with empty pores and dependency of sound speed
on pore filling factor.
Sound speed in artificial opal was calculated by taking into account internal
structure of opal. Opal consists of silica spheres of fairly regular size, packed into
close-packed planes that are stacked together with characteristic dimensions of
several hundred nm [1]. It was shown that sound speed strongly depends on compression factor what is equal to diameter of silica spheres substituted by distance
between to neighbor silica spheres and divided by two. Actually that is height of
compressed globe calotte. Unfortunately, compression factor depends on production method and it is unknown.
In order to determine the compression factor for samples under investigation we
simulated mercury porosimetry for opals with different compression factors varied
from zero to one tenth of silica sphere’s radius. We used two-dimensional section
of material. For every point the maximal radius of inscribed into pore circle, which
contains this point, was calculated. After renormalization the obtained dependency
of number of points on corresponding radius if inscribed circle could be compared
to experimentally measured mercury porosimetry [3]. It was shown that compression factor is equal to 7±3 % of silica sphere radius. At the same time the calculated
sound speed is equal to measured one at compression factor equal to 8%.
References
1. Borisov B.F. // XIX Session of Russian Acoustic Society, p. 111, (2006).
2. Borisov B.F. // XVI Session of Russian Acoustic Society, p. 15, (2003).
3. Gartvik A.V. // Doctoral thesis, St.Petersburg, (2005).
127
Modification of the electronic structure of graphene
caused by intercalation of aluminium
Yachmenev Mikchail
[email protected]
University
Graphene is new perspective material which is characterized by a linear dispersion of π-states near the K point of the Brillouin zone with the localization of
the intersection of cones of dispersion-free and filled states (Dirac point) at the
Fermi level. Using the graphene as a basic element of nanoelectronics implies its
placement on various substrates interaction to which may substantially affect the
electronic structure of graphene. This can lead to a distortion of the linearity of the
dispersion dependences, which means the loss of most of the unique properties of
graphene. It is important to find such substrates and such technological influences
that maintain the linearity of the dispersion dependences.
This work is devoted to study of the possibility of creating of graphene monolayer by cracking of propylene on the surface of a thin layer of Ni(111) deposited
on W(110) with followed intercalation of Al atoms underneath the formed graphene
monolayer. As a result, studies have shown that this technique actually leads to
the formation of graphene with electronic structure of the valence band similar
to isolated graphene with the localization of Dirac points in the K-point of the
Brillouin zone near the Fermi level.
The valence band of Al is characterized by absence of d-electrons, which largely
determine the distortion of the dispersion dependence of π-states of graphene
monolayer intercalation by atoms of noble metals with spd-valence band structure.
The investigations showed that in the case of intercalation of Al underneath graphene on Ni(111) any significant distortion of the dispersion dependence π-states
throughout the valence band is not observed.
The experiment was performed by X-ray photoelectron spectroscopy and
photoelectron spectroscopy of the valence band with an angular resolution using
synchrotron radiation at Russian-German beamline (Helmholtz-Zentrum Berlin). In
the experiment the dispersion dependences of the valence band π-states of graphene
and sp-states of Al for the systems with fully intercalated and half-intercalated Al
was measured and analyzed in combination of the analysis of the core level spectra.
Changes of the surface crystal structure and perfection of the graphene monolayer
synthesized was shown in the pictures of the LEED patterns.
128
Modification of induced spin-orbit splitting of π - states
of graphene in case of combined intercalation of Bi and
noble metals
Zhizhin Evgeny
[email protected]
Scientific supervisors: Prof. Dr. Vladimirov G.G., Prof. Dr.
Shikin A.M., Department of Solid State Electronic, Faculty of
Physics, Saint Petersburg State University
Exploration of spin and electronic structure of various nanostructured systems
have attracted increasing interest in recent years, due to the wide development of
Spintronics - a new branch of nanotechnology. Spintronics is based on exploiting
the 'spin' of the electron [1, 2].
The effect of substrate induced spin–orbit interaction causes the splitting of
electronic spins states in the π - states of graphene due to intercalation of metal
with high atomic number underneath graphene which spin-orbit splitting quantity
is very small under normal conditions [2].
The aim of our research was to investigate the influence of the spin-orbit splitting induced by intercalation of Bi atoms and the alloy of Bi with Ag underneath
graphene on Ni(111). Interest in the Bi was determined by a high atomic number
z = 83 and the lack of the valence band d electrons. At the same time it is assumed
that the joint intercalation of Bi and Ag due to mixture of Bi states with d states
of Ag will result in the induced spin-orbit splitting caused by combination of high
atomic number and hybridization effects.
The experiment was carried out in the Helmholtz-Zentrum (BESSY II) at the
Russian-German beamline using the methods of photoelectron spectroscopy with
angular and spin resolution. At the result the dispersion dependences were measured
with spin resolution for the systems with intercalated Bi and the alloy of Bi with
Ag with different stoichiometry. It was found that the intercalation of Bi under
graphene does not lead remarkable value of the spin-orbit splitting. Thereat, it was
established that the joint intercalation of alloy of Bi with Ag noble metal can induce
the spin-orbit splitting of the π-states of graphene with variable splitting value.
It was found that availability of only high atomic number Z of intercalated
atoms is insufficient for the effect of the induced spin-orbit splitting of the π-states
of graphene. The hybridization of graphene π – states with d - states of intercalated
metals of alloy of Bi with Ag is also necessary.
References
1. Rashba E.I. Spintronics: sources and challenge // J. Supercond. Vol. 15, no. 1,
2002, pp. 13–17.
2. Rybkin A.G. Electronic, energetic and spin structure of the thin layers of metals
induces by spin-orbit interaction. - St. Petersburg, 2010.
129
E. Applied Physics
Usage pocket COMSOL for the numerical nonstationary
nonlocal plasma modeling
Burkova Zoya
[email protected]
Scientific supervisor: Dr. Chirtsov A.S., Department of General
It’s easy to use a numerical simulation to simulate wide range of systems,
which is interesting for physics. Software package COMSOL is well adapted to
solve such problems. There are a lot of modules in this software. One of them is
the plasma module.
In this work has been carried out the simulation of DC Discharge. Argon
has been chosen as an active medium. Two measurements have been carried
out: for Argon with metastable level and without. Software package COMSOL
can simulate only one task in a session. What’s why has been used the software
Wolfram Mathematica to compare the results. Plot data has been saved in a text
file in COMSOL and has been exported in Wolfram Mathematica.
132
Factorization of charge formfactors for clusterized light
nuclei in reactions e+16O and e+12C
Danilenko Valeria
[email protected]
Scientific supervisor: Prof. Gridnev K.A., Department of Nuclear
There are some cases in which one can use a model of binding alpha-particles
[1] in order to describe the structure of the nuclei. It can also useful for identifying
the properties of the elastic scattering of the electrons. It is known nowadays that
light nuclei (up to calcium) have a cluster structure – an alpha-particle structure.
At the describing the elastic scattering of the electrons one can find it appropriate
to express the elastic scattering differential cross section through the formfactor. If
we consider electrons it is a charge formfactor. Formfactors in the case of cluster
structure can be factorized as two multipliers: one for distribution of clusters in
nuclei and the second for the cluster formfactor itself.
The light nuclei consist of alpha-particles and the formfactor (spherical Bessel
function) represents a spherical shell made of alpha-particles. We consider two
possible types of the alpha-particle distribution – surface and volume distribution.
In the first case the formfactor will be proportional to the Bessel function of order
zero and in the second case it will be proportional to the Bessel function of order
one.
The research covered two reactions e+16O and e+12C at different energies. The
angle distributions of the cross-sections are presented in the Fig. 1.
Fig. 1. Angle distributions of the cross-sections.
References
1. Gridnev K.A., Torilov Yu S., Gridnev D.K., Kartawenko V.G. and Greiner W.
// Int. J. Mod. Phys. 14 (2005), 635.
133
Modeling of microdischarges in air at atmospheric
pressure with Comsol Multiphysics software
Demidov Evgeny
[email protected]
Scientific supervisor: Dr. Bogdanov E.A., Department of General
Physics I, Faculty of Physics, Saint-Petersburg State University
Scientific and applied interest in the high-pressure glow microdischarge is
largely due to the fact that it does not need expensive and bulky vacuum equipment.
The microdischarges in air are of particular interest, because air is most common
gas. As a result, facilities using this type of discharge are much cheaper and easier
to operate.
In experiments, high-pressure discharges are maintained only if their size is
small. Reasons are the following. It is known [1] that optimal conditions for glow
discharge initiation and maintenance are near a minimum in the Paschen curve,
where pL = 0.5–5.0 cm Torr (p is the gas pressure and L is the interelectrode
gap). Therefore, when the pressure is low (p ~ 1 Torr), the size of the discharge
region is typically equal to several centimeters or more, while at a high pressure
(p = 100–760 Torr), the discharge region shrinks to several millimeters or even
micrometers. Such microdischarges [2] are characterized by an elevated energy
deposit, all other things being the same. Since heat removal conditions grow worse
at a high pressure, the gas is heated more strongly than in low-pressure discharges
[1, 2]. That the gas temperature in high-pressure discharges (in which charges are
lost in volume processes rather than at walls or electrodes) rises is well known
and well studied for extended discharges with a positive column [1]. It has been
found in many experiments that developing thermal instabilities lead, in this case,
to a descending voltage–current characteristic of the column and, consequently,
make the discharge unstable. Unfortunately, despite much practical interest in the
microdischarge because of its stability, the effect of gas heating on its characteristics
has been poorly understood.
In this work, we carried out 1D simulations of the microdischarge in air at
atmospheric pressure and two interelectrode gap widths, L = 0.1 and 0.4 mm.
Numerical model includes balance equations for electrons, positive and negative
ions, electron and gas temperatures and Poisson equation, which are solved by
finite element method, with Comsol Multiphysics software (version 4.2).
It is shown that, as a result of heating the gas and a decrease in its density,
the discharge takes the form of the obstructed discharge with abruptly growing
Voltage-Current trace.
References
1. Raizer Yu. P. Gas Discharge Physics. Intellekt, Moscow, 2009; Springer, Berlin,
1991.
2. Fridman A., Chirokov A., Gutsol A. // J. Phys. D:Appl. Phys. 38, R1 (2005)
134
Polarized static Fourier - spectrometer static fourierspectrometer
Gorbyk Sergiy
[email protected]
Scientific supervisor: Dr. Myagchenko Yu.O., Department of
Experimental Physics, Faculty of Physics, Kiev National Taras
Shevchenko University
This paper considers the principle of a static Fourier spectrometer (SFS) of
polarization type (PT) own designed spectrometer and its advantages over other
spectrometers. The phase difference between interfering beams of the described
device is formed by the rigid crystals of optical system, which ensures its stability
during operation in high vibration conditions. Device is designed as a compact
monoblock, which also improves the reliability of measurements. The volume of
the spectral device is smaller than a tennis ball. Significant area of localization of
interference pattern allows direct measurement of the intensity of the interference
pattern without use of optics, which reduces the size and simplifies the measurement
process. Speed of measurements is limited by the time of registration of CCD
(“Charge- Coupled Device”). Features of the data processing, which is based on
a theorem of scaling the Fourier transform, allows “free” positioning of CCD matrix relative to the SFS. Furthermore SFS PT has one important advantage over
other SFS - the ability to measure polarization characteristics of radiation. The
device tested by measuring the emission spectra of white LEDs. Inverse Fourier
transform of the detected spectrum agrees well with the spectrum obtained by the
“usual” method.
135
Calibration and normalization problems in X-ray
diffractometry for aluminum industry
Gruzdev Mikhail
[email protected]
Scientific supervisor: Prof. Ivanov V.S., Department of Photonics,
The control of the electrolyte characteristics (the cryolite ratio, CaF2 and
MgF2 contents) is necessary in aluminum industry to reduce the power cost and
to increase the yield. The X-ray diffraction technique are using practically for
these purposes.
A comparison of classical and chemometrical methods of the data analysis
is performed to light strengths and weaknesses of these two approaches. The
X-ray diffractometer “Difrey 401” data, organized for solving calibration and
normalization problems, were used for the comparison.
136
Local dynamics of director reorientation liquid crystal
in 90° twist cell
Krainukov Evgeniy
[email protected]
Scientific supervisor: Dr. Kovshik A.P., Department of Polymer,
τoff (ms)
Phenomenon of the return back of the extraordinary beam incident on the LClayer with continuously changing director profile at the large angles was investigated
in [1]. Return of the beam takes place at the different distances from layer boundaries
depending on the incidence angle value. Applying the electric field perpendicular to
the layer plane breaks the director initial configuration, therefore beam’s trajectory
changes and for the certain range of incidence angles light propagates through the
cell [2, 3]. In the present work such deviation in trajectory of the light beam was
studied in the 90°-twisted LC cell filled with the chiral mixture (helix pitch P0= 32
mkm, dielectric anisotropy Δε =+11.7). Thickness of LC layer was 9 mkm. Electric
field (f =20 Hz - 10 kHz), applied along the helix axis breaks the extraordinary
ray turn back conditions and light beam passes through the cell. Decay time toff of
the effect was measured
E
for the different incidence
400
angles which exceed the
350
angle of ordinary beam
300
total internal reflection.
This allowed us to obtain
250
director’s initial profile
200
recovery times at the dif150
ferent distance from layer
100
boundary. Recovery time
50
of the director’s initial
configuration lowers with
0
the decreasing of the ex-50
traordinary ray penetra1
2
3
4
5
6
7
8
9
tion depth.
Z (µm)
References
1. Frederiks V., Zwetkoff V. // Phys. Zeit. der Sow., v. 3, № 2, p. 163, (1934).
2. Mendoza C.I., Rayes J.A. // Appl. Phys. Lett., v. 3, № 2, p. 163, (2006).
3. Karetnokov A.A., Karetnikov N.A., Kovshik A.P., Rumcev E.I., Aksenova E.V.,
Krukov E.V., Romanov V.P.// Opt. and Spect., v. 3, № 2, p. 163, (2009).
137
Evolution of highly oriented pyrographite surface
morphology induced by a focused electron beam
Manukhova Alisa
[email protected]
Scientific supervisors: Dr. Zhdanov G.S., Department of Photonics,
Prof. Chizhov Yu.V.,Faculty of Physics, Saint-Petersburg State
University
Focused electron beam induced processing (FEBIP) is a versatile technique
which uses electron stimulated decomposition of adsorbed molecules to produce
three-dimensional structures with nanometer scale dimensions. Various applications
of FEBIP range from repair of lithography masks to high resolution patterning.
The extending use of FEBIP is hindered by “proximity effect”, i.e. the growth rate
dependence of each next feature in the emerging pattern on the spatial distribution
of adjacent features. There has been considerable effort to elucidate complex
electron -solid-adsorbed precursor interactions. However, unequivocal quantitative
interpretation of experimental data is rarely possible and many questions remain
[1]. A valuable insight may be gained by using “spot mode” when substrate is
illuminated by a stationary electron beam .
Here we report on dynamics of nanorelief formation on the surface of highly
oriented pyrographite (HOPG) induced by a nanometer size electron probe.
HOPG consists of extended graphene sheets with atomically flat terraces without
appreciable concentration of surface oxides even in non-UHV conditions. Substrate
irradiation was carried out inside a specimen chamber of Crossbeam 1540XB at
accelerating voltages 3…20 kV and beam currents 10-400pA. Mass spectrometry
analysis showed the presence of n-alcanes (partial pressure of 10-8 ...10-9 Torr). Their
polymerization leaded to formation of a spot with complicated structure. The spot
size exceeded by three orders of magnitude the diameter of primary beam. The
surface morphology was analyzed by scanning electron (SEM) and atomic-force
(AFM) microscopes.
The observed evolution of surface morphology differs from those reported
earlier on silicon and some other substrates [1]. The main distinctions are i) the
vertical growth of carbon nanopillar ultimately slows down and may be replaced by
evaporation. ii) several concentric rings are formed inside an area restricted by the
backscattered electron range. iii) the roughness of carbonaceous deposit increase
with time leading to a pattern formed by alternating protrusions and troughs with
vertical dimensions as small as 1 nm. Possible explanations of observed phenomena
are discussed.
References
1. 1. Utke I. et. al. // J.Vac.Sci.Technol., B 2008, 26, 1197-1276.
138
Study of interaction forces between constant magnet and
high-temperature superconductor
Marek Veronika
[email protected]
Scientific supervisor: Dr. Chirtsov A.S., Department of
General Physics - I, Faculty of Physics, Saint-Petersburg State
University
The high-temperature superconductivity is interesting in terms of both theory
and practice. Despite lack of a complete theory this topic is traditionally learned
in classical physics courses. That’s why an interactive demonstrations set and a
video clip about a soaring’s mechanism of the constant magnet over the hightemperature superconductor have been created [1]. During the video clip making,
existence of a space interval where the magnet is in a neutral equilibrium instead
of expected stable one has been found out. Then an installation which allows
measuring a magnet altitude dependent on an applied external force has been
made up. Thereby obtained plot showed there were no hysteresis effects in case of
large distances between the magnet and the superconductive ceramics. In case of
an interval double decreasing one can observe the strong hysteresis effect and the
presence of several magnet equilibrium states. Moreover after ending of an outer
force action the magnet doesn’t return to its initial position.
To explain these phenomena two models have been considered��
. T��
he “hard derangement model” supposes when current passing on the superconductor exceeds
a critical value icr, a destruction of a superconductive state occurs. The second
model is the model of critical Bean state [2]. By means of mentioned models and
the image method an analytical description of the phenomena has been worked
out. It has been assumed when induced currents exceed the critical value a circle
of a disturbed superconductivity appears. Inside this circle induced currents turn
either to zero or to the critical value, in correspondence with used models.
However this analytical description doesn’t take into account several features.
That’s why the Laplace problem for a vector potential with mixed-boundary conditions
appears. The problem has been solved by the relaxation method that has allowed calculating a lifting force acting to the magnet. A computational modelling of the experiment
has showed the “hard derangement model” is more applicable than the Bean’s one.
The described equipment and the measuring technique can be considered as
a model for an educational laboratory work on the magnetic levitation over the
high-temperature superconductor.
References
1. Марек В.П., Чирцов А.С. // В сб. «Материалы XV Межд. конф. “Современное
образование: содержание, технологии, качество” 22 апреля 2009 г., Т. 1, СПб,
2009. С. 219-221.
139
Usage of stereoscopic 3d-visualization technologies
Marek Veronika
[email protected]
Scientific supervisor: Dr. Chirtsov A.S., Department of
General Physics - I, Faculty of Physics, Saint-Petersburg State
University
There are a lot of situations when it’s difficult to apprehend a 3-dimensional
(3D) computer model by means of its plane 2D projection. This problem has been
solved partially due to a possibility of the model’s rotation relative to a monitor’s
plane. However creation of 3D stereoscopic images and virtual reality technologies
becomes more and more popular today [1]. To create a stereoscopic image it’s
necessary to project two pictures recorded by two space-apart observers on two
eyes’ retinas. This can be fulfilled by different ways, e.g. the anaglyphic method
uses chromatic selection of images for each eye, the polarization one - light beams
with different polarizations.
A developed stand for stereo visualizations includes two multimedia projectors
fixed on movable brackets, linear polarizers and a screen with a metallic surface
which. For viewing stereo images a polarized glasses have been used.
Possibilities of physical systems stereo images creation by means of a simulating
program for plane objects have been studied (by means of a built-in function of
models rotation). Similar opportunities are provided by Autodesk 3ds Max program
shell: a set of video clips which visualizes an atomic vector model and different
calculating approximations has been carried out in this way (for a course “Quantum
theory of atomic and molecular spectra”).
A new application of stereo technologies is “plane” 3D projections of highdimensional systems, e.g. a 3D representation of the 4D Minkovsky time-space and
the light cone. The 3D projection of the light cone is a set of parallel 3D planes ct =
const disposed perpendicular to the time axis. Worked out stereo clip demonstrates
the light cone (c2t2 – r2 =0) and one- and two-sheeted hyperboloids (c2t2 – r2 = ±A2,
A=const). An upper part of the one-sheeted hyperboloid represents a four-velocity
space where a squared absolute value for each vector is a constant and is equal to
the squared speed of light.
References
1. Андреев C.В., Денисов Е.Ю., Кириллов Н.Е. // "Программные продукты
и системы", № 3, 2007, с. 37-40.
2. Колинько К.П., Никольский Д.Ю., Чирцов А.С. Многофункциональный компьютерный учебник по фундаментальному курсу физики. Разделы: “Движение
частиц в силовых полях”, “Релятивистская динамика”, “Геометрическая
оптика” // В сборнике трудов IV Международной конференции “Физика в
системе современного образования”, Волгоград, 15-19 сентября 1997 г.
140
Development of a dielectric barrier discharge ion source
for ion mobility spectrometry
Pechatnikov Pavel
[email protected]
Scientific supervisor: Dr. Klucharev A.N., Department of Optics,
Ion mobility spectrometry (IMS) is a simple and potentially inexpensive
analytical technique that has been utilized for many analytical applications with the
most essential being detection of toxic compounds. About 90% of all commercial
gas analyzers for detection of chemical agents are based on IMS. One of the major
limitations of modern IMS technology for the detection of chemical substances is
the lack of suitable ion sources for such devices.
In this work, a new dielectric barrier discharge ion source for IMS is described.
The ion source operates at ambient air and has simple design based on surface
barrier discharge. The power supply for barrier discharge is based on piezoelectric
transformer, which allows low power consumption and portability of the system.
The construction procedure is described and the electrical characteristics of
the ion source are investigated. Ion current from the ion source is measured and
compared with conventional corona discharge ion sources. Finally the developed
ion source is coupled to an IMS and the reactant ion spectrum is obtained. The
preliminary results showed that the described ion source has great potential
applications in IMS and can replace conventional corona discharge ion sources.
141
Application of the methods of information theory by the
example of the measurement of kinematic quantities
Peganov Sergey
[email protected]
Scientific supervisor: Dr. Kryukov N.A., Department of Optics,
The definition of the fundamental concept of measurement tells [1]:
“Measurement is sequence of experimental and computational operation carried
out in order to find the value of a physical quantity that characterizes an object
or phenomenon. … The measuring ends with determination the degree of the
approximation of the found value to the true value of the quantity (if there is no a
priory information).” The definition does not indicates when to break this sequence
of operations and what if the accuracy of gotten quantity.
It is necessary to get the information
in spatial and time coordinates in the
corresponding scale to find kinematic
quantities. In any coordinates system
the information of event is always finite
quantity, and for its transfer finite time is
required [2].The concept of time is based
on observation of changes of system's
states. In this sense, time is a duration of
Fig. 1. The average information rate the given process on the scale of reference
from the value depending linearly on process duration. For registration of
number of sample's possible values for change of a state in reference process it
memory size of 16 bits.
is necessary to memorize current states
of system. So, the measuring time device(clocks), includes periodic process and
memory. The volume of physically realizable memory is limited.
The dependence of average information rate on memory size is calculated,
using a Shennon's definition of average information rate [3] source characteristic.
It is shown that the information maximum volume is gained in the limited interval
of number of sample's possible values for the given memory size (Fig. 1). The
results of the work allow to formulate the criterion of measurements accuracy for
the given experimental conditions.
References
1. Физический энциклопедический словарь. – 4-е изд., – М,: Большая российская энциклопедия, 1998. – 944 с.
2. Хармут Х. Применение методов теории информации в физике: Пер. с
англ. – М.: Мир, 1989. – 344 с.
3. Панин В. В. Основы теории информации: учебное пособие для вузов. –
2-е изд., – М.: БИНОМ. Лаборатория знаний, 2007. – 436 с.
142
Evaluation of the influence of readout cables in the CBM
silicon tracking system
Prokofyev Nikita
[email protected]
Scientific supervisor: Dr. Kondratyev V. P. Department of Nuclear
The Compressed Baryonic Matter (CBM) experiment at Facility for Antiproton
and Ion Research (FAIR) explore the properties of highly compressed nuclear
matter in violent heavy-ion collisions. The Silicon Tracking System (STS) is the
heart of the CBM experimental setup. The novel concept of STS has been studied
on the virtual models. The STS consists of several hundreds of silicon microstrip
sensors up to 62 mm x 62 mm in size [1]. The signals of every sensor must be red
out through multi-line low-mass flexible cables made from polyimide spacer and
aluminum foil wires. Due to the large number of sensors, there are large amounts
of cables (e.g. media that may lead to multiple scattering and other phenomena)
presents in the active volume of the detector. Simulations with different STS
models have been performed. The aim of the simulations is to evaluate the impact
of the readout cable on the STS performance. A realistic model (all cables consist
of separate GEANT volumes) and a silicon-equivalent model (thickness of silicon
sensors increased corresponding to number of cable layers) have been studied and
compared with ideal model without any materials but the sensors.
References
1. Heuser J.M. et al. // CBM Progress Report 2010, p. 14, (2011).
143
Application of graph theory to modeling of the complex
hydraulic systems
Strizhenko Olga
[email protected]
Scientific supervisor: Dr. Slavyanov S.Yu., Department of
Computational Physics, Faculty of Physics, Saint-Petersburg
State University
This work covers the actual problem of design and maintenance of complex
hydraulic systems (or pipeline network), which play very important role in the life
of humankind. People use given systems for oil and gas transportation, water and
heat supply in the cities, irrigation etc.
Hydraulic system is defined as a set of different facilities (pump stations,
pressure regulators, shutters etc.) and connecting them pipelines, closed or open
channels involved in the transportation of compressible and incompressible fluids
(water, oil, gas etc.) [1].
Hydraulic systems are a well known example of a complex and large scale
distributed parameter system. By this reason the modeling approaches, numerical
methods and optimization of operating modes of fluid transport networks are
of permanent interest for researchers and engineers who create more and more
perfect simulators (OLGA [2], PipeSim [3], Stoner etc). But all these simulators
have common concepts of graph representation of hydraulic network, which
appeared several decades ago at the inception of the theory of hydraulic circuits.
In this work author described common concepts of graph representation of
pipeline network, supplement topology matrices of graph model to formulate
Kirchhoff’s laws for flow distribution problem solving, structure of the hydraulic
simulator prototype «Pipeline Network» and extension of the prototype for the
tasks of leak detection as well.
References
1. Merenkov A., Hasilev V. Theory of hydraulic circuits. - Moscow: Nauka, 1985
– 276 p (in Russian).
2. Bendiksen K.H., Malnes D., Moe R., Nuland S. The Dynamic Two-Fluid Model
OLGA: Theory and Application / SPE Production Engineering, May 1991, pp.
171-180.
3. José M. Chaves-González, Miguel A. Vega-Rodríguez, Juan A. Gómez-Pulido,
Juan M. Sánchez-Pérez. PipeSim: Pipeline-Scheduling Simulator, 8th International
Symposium on Computers in Education (SIIE'2006), pp. 109-116. León, Spain,
October 2006.
144
F. Optics and Spectroscopy
A modern implementation of Rozhdestvenski
interferometer
Agishev1 N.A., Medvedeva2 T.A., Ryabchikov1 E.L.
[email protected]
Scientific supervisor: Dr. Anisimov Yu.I., Department of General
Physics-1, Faculty of Physics, Saint-Petersburg State University
1
2
Faculty of Physics, Saint-Petersburg State University, Russia.
State educational institution lyceum №419 Petrodvorets, Saint-Petersburg,
Russia
Rozhdestvenski interferometer coupled with spectrograph is used in
researching discharge tubes produced by EDD techology. They may be promising
in laser researches, for example for creating new active media.
Modernization of the experimental assembly has touched sources of light and
photodetectors. To simplify analysis of observations CCD-matrixes were choosen.
also extra-bright LEDs were used as the optical light source. Their advantages are
obvious. Above all this is ease of use in a continues and pulsed modes and the
almost complete absence of electrical interference.
The spectral characteristics of LEDs were studied by use of specially designed
automatical monochromator coupled with a PC. The results of these measurements
are presented in this paper.
To demonstrate the working capability of the experimental assembly
Rozhdestvenski hooks on the sodium doublet were obtained.
The ultimate goal of our researches based on Rozhdestvenski interferometer
coupled with spectrograph is creation of experimental assembly operated in
pulsed mode with high time resolution (0.5 microseconds). This will allow to
measure non-stationary concentration of vapors of chemical substances in the
discharge tubes produced by EDD techology by Rozhdestvenski hooks.
References
1. Anisimov Yu.I., Mashek A.Ch., Metel’skii K.E., Ryabchikov E.L. // Optics and
Spectroscopy, Vol. 107, No. 3, pp. 368–370, 2009.
146
Self-organization processes in cysteine – silver solutions
and hydrogels
Andrianova Yana
[email protected]
Scientific supervisor: Prof. Dr. Pakhomov P.M., Department of
Physical Chemistry, Faculty of Chemistry, Tver State University
The process of gelation in the system based on L-cysteine and silver nitrate
is of particular interest because it occurs at very low contents of dispersed phase.
Since the initial components are biologically active and play a special role in the
human body, hydrogels obtained may be a promising matrix for the creation of
pharmaceutical formulations of various actions.
The aim of this work is to study self-organization in L-cysteine based systems
by UV-visible spectroscopy, dynamic light scattering (DLS) and transmission
electron microscopy (TEM). It is established experimentally that formation of the
hydrogels occurs in a narrow concentration range of the initial components and can
be initiated by the addition of different electrolytes (salts) in so-called cysteinesilver solution (CSS). CSS is prepared by mixing the aqueous solutions of the initial
components of given concentrations taken at definite molar ratio. One of required
conditions for gelation is aging of CSS associated with the appearance and growth
of the absorption bands with maxima at 310 and 390 nm. This process strongly
depends on the temperature; with increasing temperature from 15 to 40°C the rate
of aging of CSS is increasing significantly. It is also established that the studying
system can be diluted in many times, for example, 6, 10 and 20, nevertheless the
absorption bands (310 and 390 nm) will be observed in spectra. It is important to
note that when the system is diluted in 10 times gelation does not occur, although at
6-fold dilution the gel has formed. Therefore, the gel-system can be used as a basis for
obtaining pharmaceutical preparations with ultra-low content of active substance.
DLS is a power tool to study processes of aggregation and self-organization.
By means of DLS it is found that the aging of CSS is associated with the selforganization that occurs immediately after mixing the initial components. On a first
step clusters consisting from silver mercaptide molecules participate in aggregation.
During a time, which depends on molar ration of the components and temperature,
formation of oligomeric chains takes place in the solutions that is confirmed by
TEM data. The addition of an electrolyte (chlorides and sulfates of Na+, K+, NH4+,
Zn2+, Cu2+) leads to the formation of the spatial gel network. The type of the threedimensional network depends on the initiator of gelation. On the data obtained the
mechanism of gelation in the L-cysteine system is suggested.
This work was financially supported by a grant "Development of Scientific
Potential of Higher Education (2009 - 2011 years)" № 2.1.1/6867.
147
Effect of polarity on the discharge with an electrolytic
anode and face-type, air yalf-space directed cathode
(gatchina’s discharge) and its afterglow
Astafiev Aleksandr
[email protected]
Scientific supervisor: Dr. Emelin S.E., Department of Radiophysics,
Gatchina’s discharge [1 - 3] is one of the most interesting experiments that gives
a possibility to model some properties of the balllightning on the base of non-ideal
dust chemical plasma. It is a discharge between the surface of a low conductive
solution and a metal or carbon central electrode isolated from the water via a
fused silica tube. Previously [4], we showed that under initial voltage of a storage
capacitor ~ 5 kV and a current attaining at maximum of a magnitude about tens
ampere a characteristic feature of the discharge is a setting in of a uniform current
distribution with a low density (~ 10-1 А/cm2) over the electrolytic anode surface,
while at a sufficient decrease of the current a transition to a non-uniform distribution
with a three order of magnitude greater current density occurs.
The aim of our researches was to investigate space-temporal dynamics of the
dust component of the plasma and its influence on the formation of an autonomous
luminous object. For that, electric parameters of the discharge, signals from electric
probes placed under the water surface and radiation intensity at the visible range
were measured and a video recording through optical light filters was carried out.
Also in the present paper we point out differences between the discharge regimes
of opposite polarity and indicate nature of the current distribution peculiarity with
the help of an additional experiment.
References
1. Egorov A.I., Stepanov S.I., Shabanov G.D. Laboratory demonstration of ball
lightning. UFN. 2004. V.174. No.1. P.99–101.
2. Emelin S.E., Pirozerski A.L., Vassiliev N.N. Dust-gas fireball as special form of
electric erosive discharge afterglow. Proceedings of ISBL-06, 16-19 August 2006,
Eindhoven, The Netherlands. Preprint: http://arxiv.org/abs/physics/0604115.
3. Emelin S.E., Pirozerski A.L. //Chemical Physics V.25 N.3 (2006) P.82–88.
4. Emelin S.E., Astafiev A.M., Pirozerski A.L. Investigation of space-time structure
of the discharge with an electrolytic anode and face-type, air half-space directed
cathode (Gatchina’s discharge). Proceedings of ISBL-08, 16-19 July 7, 2008.
Kaliningrad, Russia. P. 42.
148
Measurement of two-photon absorption cross-section by
method of comparison with reference samples
Belskiy Denis, Belskaya Natalia
Scientific supervisor: Dr. Pastor A.A., Department of Optics,
Cross-section of two-photon absorption of metallo-organic complexes (Pt2, Pt
(T2), Pt (T3)), dissolved in dichloromethane (CH2Cl2) and Coumarine 307, dissolved
in ethanol, have been measured in the given work by method of comparison with
reference samples. As the standard dye Rhodamine 6G, dissolved in ethanol was
used. As a light source the titan-sapphire laser with pulse duration 40 fs was
used, pulse repetition frequency 80 MHz and a wavelength of 800 nanometers.
Fluorescence was registered by means of spectrometer Ocean SD2000. Spectral
sensitivity of a spectrometer was defined by means of lamp LS-1 CAL (Ocean).
Spectra of two-photon fluorescence have been received. As a result of calculation
following values of cross-sections of two-photon absorption are received:
σ Pt 2 = 50 ± 10 GM , σ Pt (T 2 ) = 60 ± 10 GM ,
σ Pt (T 3) = 50 ± 10 GM , σ Co 307 = 13 ± 6 GM .
Value of cross-section for Comarine 307 converges with the cross-section
received in other works.
The new method of measurement of cross-section of two-photon absorption
– quenching of a laser bunch at passage in medium with two-photon absorption
has been offered.
In given experiment intensity of two-photon fluorescence along a laser beam
in a long ditch is measured. It is considered long, if intensity of a laser bunch is
considerably weakened (approximately in e time). As a two-photon absorber it was
used Rhodamine 6G, dissolved in ethanol with known concentration. In Fig. 1 is
resulted photo of two-photon fluorescence along a laser beam.
Fig.1. Photo of two-photon fluorescence along a laser beam.
Estimations show that the cross-section of the two-photon absorption defined
on the given method is close to the literary data.
References
1. Xu C., Wabb W.W. // J. Opt. Soc. Am. B V.13, № 3, p. 481 (1996).
149
Study of Rb vapor fluorescence by two-photon excitation
Bondarchik Yulia
[email protected]
Scientific supervisor: Dr. Pastor A.A., Department of Optics,
We study visible Rb vapor fluorescence excited by femtosecond laser irradiation.
The cell containing Rb was made from fused silica and allows the heating of the
vapors in the range 300 – 500 К. For the excitation the pulses of the Ti:Sapphire
femtosecond laser Pulsar 10 produced by Amplitude Technologies company were
used. Pulse duration is 40 fs, repetition rate 10 Hz and the wavelength is 790 nm.
Visible fluorescence was recorded by computer-controlled spectrograph Ocean
Optics.
Experimental arrangement and the sequence of atomic Rb transitions used in
this experiment are displayed on the Figs. 1 a) and 1 b), respectively:
Observed visible
fluorescence at 420 nm is
explained as a result of twophoton excitation of Rb atoms
from the ground state 5S to the
excited 5D state through the
intermediate quasiresonant 5P
state. Achieved results will be
used in our further experiments
devoted to coherent excitation
of the atomic transition in Rb
by femtosecond pulses of laser
radiation at the wavelength of
790 nm.
Fig.1. a) Experimental arrangement b) Scheme of
sequential two-photon pumping and fluorescence
in atomic Rb.
References
1. Aurinbold G. et al. //J. Opt. Soc. Am. B, v. 28, № 3, p. 462, (2011).
150
The research of optical spectra of oil fractions in IR-area
Chernova Ekaterina
[email protected]
Scientific supervisor: Prof. Dr. Nemetz V.M., Department of Optics,
The main goal of researching information value of oil fractions optical spectra
is a generation of a priori method for the optimization oil-products compounding
process and for the creation physicochemical parameters prediction model. These
results application can be important for the invention methods for the quantitative
analysis of oil and oil-fractions.
Traditional spectroscopic approaches have limited possibilities due to the basing
on extraction narrow frequency region with one or two characteristic components
from the complicated spectrum. Whereas different component fragments overlap
in oil-spectra, attempts to find solution by such method were unsuccessful.
Let’s consider the method of principal components (MPC) [1] applied to 32 oil
fractions, each of them was the result of 10-degree rectification.
Fig.1. Results of applying MPC. Distribution of fraction samples.
In spite of lack possibility to separate absorption bands, using precise spectra
allows to identify fraction samples.
References
1. Konushenko I.O. The new methods indentification of liquid mixtures. Diploma
tesis. Saint-Petersburg State University, Laboratory of spectrum analysis. 2008.
151
Exotic behavior of Penning ionization of two ultracold
Rydberg atoms
Efimov Dmitry
[email protected]
Scientific supervisor:Prof. Bezuglov N.N., Department of Optics,
Due to modern magneto-optical traps development research of the ionization
dynamics of cold Rydberg gases becomes important, because of the important role
it plays in the evolution of cold plasma observed in cold matter [1]. Free electron
escaping in collisions of two Rydberg atoms is possible via two mechanisms:
associative and Penning ionization. Associative ionization is comparatively short
range process of low energy, because it requires close encounters enabling overlap
of Rydberg atom wave functions. In contrast, Penning ionization is a long-range
process with atoms well space separated at antinuclear distances R>>neff2 (where neff
is the effective quantum number), which is enabled by the dipole-dipole interaction
(atomic units are used).
We consider an interaction between two Hydrogen Rydberg atoms in a big
distances, using model of dipole-dipole interaction. It's supposed, that Auger process
takes place: while first atom moves down from (ndld) to (nd'ld'), the second ionizes
from (nili) to (pi'li') state with energies ωi=ωd, ωd=1/2(nd')2-1/2(nd)2, ωd=1/2(ni')2-p'/2.
An asymptotic expression of autoionization width of the process described above
has been received from [2]:
4
17
−
 32

1
1
3  2 Γ (2 / 3)  3  1
1  3
Γ= 6
− 2 ,
3
3
1
*2

 17  2nd
R (ni nd ) 4π 
2nd 
33


where nd* - is principal quantum number of the nearest lower level to the effective
level, energy difference between which and nd equals ionization energy of ni
state.
Importantly, an interesting counterintuintive phenomena is predicted with
our results: the decreasing of the principal quantum number nd of the unionized
atom (i.e. the decreasing of its size) results in an essential jump of the ionization
efficiency.
References
1. T.Amthor, J.Denskat, C.Giese, N.N.Bezuglov et al // Eur. Phys. J. D vol. 53,
329 (2009).
2. N.N.Bezuglov, V.M.Borodin // Optics and Spectrosc., vol. 86, 467 (1999).
152
Determination of composite complexes concentration
using the data of Raman spectra matrix of binary liquid
mixtures
Ilchenko Aleksey, Kutsyk Andrey, Obukhovsky Vyacheslav,
Nikonova Viktoria, Lemeshko Vasiliy
[email protected]
Scientific supervisor: Dr. Obukhovsky V.V., Department of
Theoretical Physics and Mathematics, Faculty of Radiophysics,
Taras Shevchenko National University of Kyiv
The method to determine the concentration of composite complexes, such as
small clusters in binary mixtures XnYm liquids was proposed. Vibrations of hydroxyl
OH-groups of ethanol-water mixture have been studied by Raman spectroscopy
method at room temperature.
The concentration dependence of Raman spectra in the region 2400 – 3700
cm-1 was obtained for water-ethanol solutions.
The method was designed in order to identify ethanol hydrate lines in the spectra
of the mixtures. This technique can be used to determine the concentration of the
composite complexes in water-alcohol solutions. The disadvantage of the proposed
technique is the inability to independently determine the concentration of each pure
component of binary mixture. But it allows to separate the different types of the
composite complexes and provides the information of its quantity.
153
The study of hydrogen bond cooperativity in complexes
that simulate proton transfer in serine protease
fragment by infrared and ultraviolet spectroscopy
Klykov Alexander
[email protected]
Scientific supervisor: Shurukhina A.V., Department of Molecular
Spectroscopy, Faculty of Physics, Saint-Petersburg State
University
This work is part of the research conducted by the Department of Molecular
Spectroscopy, St. Petersburg State University with the laboratory of Professor H.kh. Limbakh at the Institute of Chemistry and Biochemistry at the Free University
of Berlin on the spectroscopic study of the structure and properties of complexes
with hydrogen bonds and proton transfer processes.
The objective of this study was to identify by IR and UV spectroscopy of the
cooperativity of hydrogen bonds in a number of model complexes the catalytic
triad of the active site of serine proteases. The objects of study were selected
intermolecular complexes formed by o-hydroxyphenyl benzimidazole (HBPI) with
organic bases of different proton acceptor ability: dimethyl sulfoxide-d6 (DMSO),
2,4,6-trimetylpyridine (Col), tributylamine (TBA), pyrollidine, piperidine and
4-dimethylaminopyridine in a solution CH2Cl2. For comparison, the complexes
were investigated with the same base phenylbenzimidazole (PBI), does not contain
an intramolecular hydrogen bond, as well as IR spectra were obtained HBPI and
PBI in the solid phase.
The presence of cooperative interaction between two hydrogen bonds in the
complexes with the bases HPBI can be demonstrated in the form of correlations
between the centers of gravity of bands of stretching vibrations of NH and OH.
Strengthening intermolecular hydrogen bond in complexes HPBI with stronger
proton acceptors leads to a low-frequency shift of the NH and OH band, which
indicates a strengthening of intramolecular communication OHN.
Most of the spectra was taken at room temperature, but the low-temperature
spectra were also obtained
References
1. Tolstoy P.M., Golubev N.S., Smirnov S.N., Denisov G.S., Limbach H.-H.
// XVIII Int. Conference on “Horizons in Hydrogen bond research”, Paris, 1418.09.2007, Book of Abstracts, p. 130.
2. Golubev N.S., Denisov G.S., Gindin V.A., Limbach H.-H., Smirnov S.N. // J.
Mol. Struct. 322 (1994) 83-91.
154
Efficient phosphors based on nanocrystalline powders
doped with europium
Kolesnikov Ilya
[email protected]
Scientific supervisor: Dr. Kurochkin A.V., Department of General
Physic I, Faculty of Physics, Saint-Petersburg State University
The aim of the present work is to study the luminescent properties of different
nanocrystalline powders doped with europium rare-earth ions and determine the
composition and synthesis conditions of the most efficient phosphor. Also in this
paper the kinetics of luminescence was investigated and the lifetimes of the excited
level of europium ions (5D0) were calculated.
Luminescence properties depend on many various factors such as the
composition of the host, the method of synthesis, the size and shape of particle
grain, the synthesis temperature and the concentration of the ligand.
The luminescent spectra of nanopowders of different composition have been
measured. YVO4 and Y2O3 were synthesized under the same conditions by the
Pechini method. The luminescence intensity in yttrium vanadate was higher than
in yttrium oxide. Therefore, further studies were carried out with yttrium vanadate
host.
The temperature dependence of luminescence has been investigated. The
emission spectra of the band with maximum at 619 nanometers were measured
for the samples synthesized at different temperatures (700, 850, 900, 950 и 1000
o
С). The most efficient phosphor was the sample annealed at 1000 oС.
Also the dependence of luminescence on the concentration of dopant ions
has been studied. The concentration of europium in a series of samples was 2, 4,
8, 12, 16 percents. The optimum concentration was determined to be 8 at.% in
yttrium vanadate host. If the concentration of dopant ions was more than 8 at.%
the luminescence intensity was reduced. This decrease is due to the concentration
quenching.
In order to determine lifetimes of the excited state of europium the luminescence
kinetics has been investigated. The experimental data were approximated by a
biexponential fitting. The non-exponential decay of luminescence is most probably
due to the different decays of the europium ions at the surface of the nanoparticles
and europium ions inside the particle. In fact, the former ones are strongly affected
by the surrounding host. Because of the non-exponential behavior of the decays
observed for nanopowders samples, the luminescence life-times were determined
as effective decay times.
References
1. Hreniak D., Doskocz J., Gluchowski P., Lisiecki R., Strek W., Vu N., Loc D.X.,
Anh T.K., Bettinelli M., Speghini A. // J. Luminescence 131 (2011) pp.473–476.
155
Resonance grating based on InGaAs/GaAs quantum well
Kozhaev Mikhail, Kapitonov Yury
[email protected]
Scientific supervisor: Dr. Petrov V.V., Department of Photonics,
Faculty of Physics, St.Petersburg State University
Significant problem of modern physics is creation of an optical computer that
will make calculations in purely optical way without dissipation of energy in
the element [1]. One of the most promising candidates for the working medium
of logic elements of optical computer are InGaAs / GaAs quantum wells (QW).
Resonant reflection spectroscopy associated with the birth of 2D-excitons is used
for studying optical properties of QW [2]. Light reflection from the "excitonic
mirror" is coherent in contrast to the photoluminescence. However, the resonant
reflection from the QW, located inside the specimen, is difficult to detect against
the background of non-resonant reflection from the sample surface. The only way
to obtain interpretable QW reflection spectrum is to have zero reflection from the
sample surface by using the Brewster geometry for the incident light: the angle of
incidence equals to the Brewster angle, and polarization is in the plane of incidence
(p-polarization).
To overcome this fundamental limitation we created resonant grating by spatial
modulation of the QW properties. In this case diffraction peaks were observed.
Travelling direction of this signal differs from the reflection direction. In this case
influence of non-resonant reflection from the sample surface is eliminated for all
incidence angles and light polarizations. Spatial modulation of QW was made
using an ion beam irradiation of the GaAs substrate prior to the MBE growth of
the heterostructure.
Array of lines with length 400 um was created on GaAs substrate by focused
beam of Ga+ ions with an energy of 30 keV. The steps between the lines was 10
um, and the linear dose was 0.1 and 2 nA*s/cm. Then three In0.02Ga0.98As/GaAs
QWs with different thicknesses (and hence different spectral position of the exciton
resonance) were grown on the substrate. The sample was studied at 9 K using an
optical bench equipped with a Ti:sapphire femtosecond laser with a wide (about
20 meV) emission spectrum. We observed resonant diffraction reflex spectra and
its temperature dependence. Diffraction spectra was measured at different incident
light polarizations and angles.
References
1. Gerlovin I.Ya. et al. // Nanotechnology 11 383–386 (2000).
2. Poltavtsev S.V. et al. // Phys. Status Solidi C 6, No. 2, 483– 487 (2009).
156
Measurements of the free-carriers relaxation time in the
InGaAs quantum wells
Krjukov Anton
[email protected]
Scientific supervisor: Dr. Pastor A.A., Department of Optics,Faculty
of Physics, Saint-Petersburg State University
Presented work is devoted to the measurement of the free-carriers relaxation
time in the InGaAs quantum wells in the femtosecond time domain. As the light
source in the pump-probe method the pulses of the Ti:Sapphire femtosecond laser
Pulsar 10 produced by Amplitude Technologies company were used. Pulse duration
is 40 fs, repetition rate 10 Hz and the wavelength is 790 nm. The measurements of
the temporal changes of the refraction index of the semiconductor InGaAs sample
caused by creating and followed relaxation of the free carriers were performed by
the scheme of the pump-probe method developed in our laboratory. Two pulses:
pumping pulse having energy of 0,1 mJ and the probing one 100 times attenuated
with variable delay illuminate the sample under Brewster angle of incidence. The
temporal changes of the reflection index were registered by the CCD camera.
The dependence of the reflection of the probe pulse versus delay for two different
delaying times between pump and probe pulses is displayed in Fig.1.
Fig.1. Time dependence of the reflection of the semiconductor InGaAs sample.
Horizontal axis – delay time, expressed in the number of the CCD camera pixels,
focused on the sample’s surface. Vertical axes – changes of the reflection coefficient
(arb. units).
Approximation of the relaxation curves by the exponential leads to the
relaxation time of the free carriers in the studied semiconductor sample, which
equals 200±30 fs.
References
1. Fry P.W. et al. // Phys. Rev. Lett., v. 84, № 3, p. 733, (2000).
157
Energy transfer in the doped aromaticnitrogencontaining polycrystals
Nosova Darya
[email protected]
Scientific supervisor: Dr. Zarochentseva E.P., Department of
General Physics II, Faculty of Physics, Saint-Petersburg State
University
Doped polycrystals were investigated. Following compounds were used
as hosts: acetanilide, benzoic acid, 2-aminobenzotiazole. Mefenamic acid,
N-phenylanthranilic acid, niflumic acid were used as quests.
Introduction of moleculs of N-phenylanthranilic acid (niflumic acid) in
acetanilide and benzoic acid (benzoic acid) courses increasing of intensity of the
guest luminescence. The growth of intensity of the guest luminescence can be
explained by the restriction of intramolecular rotations in matrix, which reduces
the probability of nonradiative vibrational and rotational degradation of energy.
Intensity dependence on the excitation wavelength was evaluated in polycrystals
of benzoic acid doped with N-phenylanthranilic acid. Upon excitation into the
absorption band of host the guest luminescence becomes more intensive than the
host luminescence. This effect indicates transfer of electronic excitation energy
from the host molecules to the guest molecules.
Luminescence spectrum of the 2-aminobenzotiazole polycrystals doped with
mefenamic acid is a superposition of the more intensive spectra of individual
crystals of host and guest. Increasing of the excitation spectrum intensity also has
been observed. The intensity ratio of maxima of vibrational structure of spectra
of the doped sample indicates the predominance of the guest luminescence. Thus
the transfer of electronic excitation energy from the host molecules to the guest
molecules also occurs. It was found that decreasing guest concentration leads to
decreasing of luminescence intensity of the doped sample, but a further decreasing
of the guest concentration results in growing of luminescence intensity of the doped
sample and the clearest resolution of vibrational structure. The reason for this effect
is two different types of embedding of guest molecule in crystal lattice of the host.
At low concentrations more attractive positions with minimum energy — guest
traps — are filled. Then introduction of "quasi-free" molecules occurs forming of
substitution solid solution, which leads to different kinds of spectra.
References
1. Zarochentseva E., Korotkov V., Oleinik Ya., Kholmogorov V. // Optics and
Spectroscopy, Vol. 77, No. 4, pp. 597—600, 1994.
158
Luminescence of solutions of mefenamic acid
Nosova Darya
[email protected]
Scientific supervisor: Dr. Zarochentseva E.P., Department of
General Physics II, Faculty of Physics, Saint-Petersburg State
University
According to the authors [1]: non-emissive silole molecules in solution have
been induced to emit strong fluorescence in crystal phase. This phenomenon is
attributed to formation of J-stacking-aggregates. Study of intra- and intermolecular
interaction of these compounds revealed the correlation between their molecular
packing modes and photoluminescent properties. Present paper is devoted to
investigation of luminescence of crystalline state and solutions of mefenamic
acid. It was found that luminescence spectrum of mefenamic acid in crystalline
state obtained using excitation irradiation with λex = 330 nm contains a maximum
at λ = 435 nm.
Luminescence spectra of different dichloromethane solutions of mefenamic acid
are characterized by the following features. A luminescence spectrum of mefenamic
acid at 10-4 mol/l concentration exhibits the long wavelength shift of the maximum to
465 nm comparing with the crystalline state. An excitation luminescence spectrum
of this solution shows the clearest resolution of structure comparing with the
crystalline state. Instead of maximum at 330 nm two new maxima are observed:
at 270 and 345 nm. Decrease of concentration of the solution to 10-5 mol/l leads to
reduction of the intensities of luminescence and excitation spectra by 2.7 times. The
positions of the maxima do not change. Increase of concentration of the solution to
10-3 mol/l causes disappearance of luminescence upon excitation irradiation with
λex = 270 nm, while the position of the maximum of the luminescence spectrum for
λex = 315 nm does not change. Excitation luminescence spectrum of this solution
at λdet = 465 nm contains two separate bands: at λ = 315 nm and λ = 410 nm.
Excitation luminescence spectrum of this solution at λdet = 485 nm shows the same
intensity of the maximum at λ = 315 nm and increase of intensity of the maximum
at λ = 410 nm. Increasing of concentration of the solution to 10-2 mol/l leads to
appearance of weak luminescence for λex = 270 nm, and a significant increase of
luminescence intensity for λex = 420 nm. Excitation luminescence spectrum of this
solution at λdet = 450 nm contains peak at λ = 420 nm. Value of this pear decreases
at λdet = 465 nm and λdet = 500 nm.
References
1. Tianlei Zhou, Feng Li, Yan Fan, Weifeng Song, Xiaoyue Mu, Hongyu Zhang
and Yue Wang. // Chem. Commun., 2009, 3199-3201.
159
Asymmetry of saturated absorption resonances
Okhinchenko Ivan, Shapochkin Pavel
Scientific supervisor: Dr. Krylov I. R., Department of General
Physics-1, Faculty of Physics, Saint-Petersburg State University
Saturated absorption laser spectroscopy is one of the most interesting methods
for spectrum analysis of molecules. It provides highly-precise information about
energy levels structure of material under investigation. But unfortunately, as we
found during our research, saturation absorption resonances are affected by some
asymmetric deformations. These deformations contribute small error in detecting
the central frequency of spectral line. Therefore the stability and reproducibility of
frequency are limited in high-precise measurements if we're stabilizing our laser
on saturation absorption resonances.
The aim of the present work is to investigate the source of asymmetry in
saturation absorption resonances of opposite light beams. It was found that 2 main
reasons cause this asymmetry: the light reflected from optical part of apparatus
back into laser cavity, and the effect of induced lens appearing inside the basin
with gas under investigation. Theoretical interpretation of asymmetric component
of resonance shape was proposed. This interpretation was confirmed with practical
measurements. Some thoughts about the behavior of asymmetry component and
the methods to eliminate this stray component were deducted.
160
Plasma-chemical processes in N2-CH4 discharge plasmas
Pechenkina Olga
[email protected]
Scientific supervisor: Dr. Grigorian G.M., Department of Optics,
The attention to plasma-chemical kinetics in N2 –CH4 discharge plasmas has
been motivated by a widespread interest in different domains of applications such as
the atmospheric chemistry of Titan, combustion processes, plasma-based synthesis
and many others fields [1, 2].
The aim of the present work was the theoretical study of plasma-chemical
processes in the plasma of gas discharges in N2-CH4 mixtures in conditions typical
for plasma-chemical reactors used for the synthesis of carbonitrides. The special
attention was paid on the vibrational kinetics of nitrogen. In observed conditions
concentrations of vibrationally excited N2 molecules may be high. But so far,
processes involving the vibrationally excited N2 molecules and their influence on
plasma-chemistry in such plasmas are not well studied. Therefore, new data are
especially desirable to improve theoretical models.
In our investigation the processes in the axial region of the discharge tube
were involved into consideration. The reduced electric field strength (E/N), the
gas temperature and the degry of dissociations of N2 and CH4 were taken from
experimental measurements. The EEDF function was calculated for our conditions
by I.V. Kochetov by solution of Boltzmann equation in the two-term spherical
harmonic approximation using the method described in [3]. Analytic theory of
vibrational kinetics was used for the calculation of the vibrational distribution
function for nitrogen molecules in the gas discharge plasma. The cross sections for
the electron excitation of electronic states of diatomic plasma-chemical products
- CN, СH, C2 were calculated in Born approximation.
Investigations have shown that concentrations of vibrationally excited and
metastable molecules of N2 are high (more than concentration of the elecrtons)
and processes involved these species play an important role in plasma chemical
reactions in the discharge plasma (in particularly in dissociation processes and in
excitation processes of plasmachemical products).
This study was partially supported under grant № 10-02-01289а of Russian
Foundation for Basic Research.
References
1. Pintassilgo C.D. et al. // J. Phys. D: Appl. Phys., v.40, p.3620, (2007).
2. Loureiro J. et al.// PSST, v.20, p.024007, (2011).
3. Konev Yu.B., Kochetov I.V., Pevgov V.G., and Sharkov V.F. // Preprint No.
2821, Kurchatov Inst. of Atomic Energy, Moscow, 1977.
161
Proton positions in strong hydrogen bonds studied by
H/D isotope effects in NMR spectra
S.A. Pylaeva1, T.A. Krinitskaya1, B. Koeppe2, P.M. Tolstoy1,2
[email protected]
Scientific supervisor: Dr. Tolstoy P.M., Faculty of Physics, SaintPetersburg State University
Faculty of Physics, Saint-Petersburg State University, Russia
Institute of Chemistry and Biochemistry, Free University of Berlin,
Germany
Hydrogen bonds are crucial for the function of proteins. Often, position of a
single proton in the active site determines the function of the whole molecule. The
aim of this research is to develop a method to locate the bridging proton in OHO
bonds using H/D isotope effects on 13C NMR chemical shifts. As a test object
we have selected complex of 2-chloro-4-nitrophenol and phenylbutyrate anion
dissolved in CD2Cl2 at ca. 170 K (Fig. 1a). A short and strong H-bond is formed
under these conditions, where the proton position is hard to predict from the acidbase properties of the interacting fragments alone.
1
2
13
O H/D
C
a)
O
O
Cl
O H/D
13
C
C
NO2
b) O
O
C
NO2
Fig. 1. a) complex of 2-chloro-4-nitrophenol and phenylbutyrate anion; b) complex
of acetic acid with 4-nitrophenolate.
We show that, surprisingly, in the studied complex the carboxylate is protonated,
while the negative charge is localized on 2-chloro-4-nitrophenolate mostly. This
seems to contradict the pKa values of these substances in water (5.45 for 2-chloro4-nitrophenol and 4.75 for phenylbutyric acid).
To understand why isotope effects appear and how they are linked to H-bond
geometry, we carried out ab initio calculations for a similar system, namely a
complex of acetic acid with 4-nitrophenolate (Fig. 1b) in vacuum. First, we have
calculated potential energy surface along the proton transfer coordinate, positions
of energy levels and corresponding wave functions for H and for D. Using this we
have found vibrationally averaged chemical shifts and isotope effects. We conclude
that the H/D isotope effect on chemical shift could be mostly ascribed to the isotope
effects on r(OH) distance which responds sensitively to the anharmonicity of the
proton potential. For example, sign of the isotope effect should change when proton
passes the center of the H-bond and the sign of anharmonicity changes.
This work was financially supported by DAAD, DFG and RFBR.
162
Coherent excitation of neon in the extreme ultraviolet
regime
C. Raschpichler, J. Plenge, A. Wirsing, B. Wassermann, E. Ruehl
[email protected]
Scientific supervisor: Prof. Dr. Ruehl E., Institute of Chemistry
and Biochemistry, Freie University Berlin
Coherent excitation of atomic transitions is a general phenomenon that may
result in various kinds of processes, for example coherent transients. Coherent
transients result in an oscillation of the excited state population and are a signature
of interferences between resonant and non-resonant excitation pathways. This
fundamental process has been investigated using ultrashort laser pulses in the
near infrared regime where atomic rubidium is often used as a model system [1].
The manipulation of the interaction process between the laser light and the atomic
system and coherent control of the excited state population has been demonstrated
by applying pulse shaping techniques in the near infrared region [2].
An extension of the investigation of these fundamental processes from the optical
to the extreme ultraviolet (xuv) regime has become feasible with the development of
ultrashort xuv light sources. High-order harmonic generation is a well-established
technique for producing ultrashort radiation in the xuv range. Recently, spectral phase
modulation of 15th harmonic of an 805 nm pulse and coherent transient excitation
of the 1s3p state in helium atoms has been demonstrated [3].
In this work we investigate the coherent excitation of a superposition of Rydberg
states in neon by the 13th harmonic of an intense 804 nm pulse and the formation
of a wave packet [3]. We present pump-probe experiments performed on the 3d
manifold of neon where the 2p6 → 2p53d (2P3/2) 3d [1/2] and 2p6 → 2p53d
(2P3/2) 3d [3/2] transitions are excited at 20.04 eV photon energy. The temporal
evolution of the excited wave packet is probed by ionization with a time-delayed
804 nm pulse. We demonstrate the control of the coherent transient excitation of
neon and the wave packet dynamics in the xuv regime using the spectral phase
of the 13th harmonic as a control parameter, where the modulation of the phase
is achieved by propagation of the xuv pulse through a variable optical density of
neon gas. The experimental results indicate the possibility to control fundamental
coherent excitation processes in the xuv regime using phase-shaped high-order
harmonics.
References
1. Zamith S., at all // Phys. Rev. Lett. 87, 033001 (2001).
2. Dudovich N., Oron D., Silberberg Y. // Phys. Rev. Lett. 88, 123004 (2002);
Degert J., Wohlleben W., Chatel B., Motzkus M., Girard B. // Phys. Rev. Lett. 89,
203003 (2002).
3. Plenge J., Wirsing A., Raschpichler C., Wassermann B., Ruehl E., // Faraday
Discuss. 153, 361 (2011).
163
Characterization of structures with quantum wells using
the resonant exitonic reflectance spectroscopy
Ryzhov Ivan
[email protected]
Scientific supervisor: Dr. Petrov V.V., Department of Photonics,
When creating a semiconductor nanostructures with quantum wells there
appears a problem of finding some standardized method for characterization of
these structures. Characterization procedure must meet two requirements: the
method should be easily reproducible and its results should clearly describe the
properties of the sample, which are interested by researcher. The photoluminescence
spectroscopy method is mainly used for the characterization of quantum structures.
However, due to the nonequivalence of the photoluminescence spectra to absorption
spectra of quantum wells there is much greater interest in the spectroscopy of the
reflected signal [1].
In this work we consider the exciton resonance spectroscopy of reflection from
the sample with InxGa1-xAs/GaAs quantum wells grown by molecular-beam epitaxy.
The simulation of the spectra was made. The effectiveness and advantages of this
method for the characterization of quantum structures were demonstrated.
In our experiment the structures with quantum wells were placed in a closedcycle helium cryostat with working temperature of 8-9K and were excited by a
femtosecond Ti:sapphire laser. The measurements were performed with light which
was reflected at Brewster's angle. The advantage of choosing this angle lies in the
fact that the p‑polarized (in the plane of incidence) light passes completely into the
sample, thus reflecting only on the quantum well. The s‑polarized (perpendicular
to the plane of incidence) light is reflected from the surface, and its spectrum
corresponds to the laser spectrum. The p- to s‑polarized light spectra ratio gives the
reflection coefficient absolute value dependence on the wavelength. The spectral
position, radiation width, homogeneous and inhomogeneous broadening of the
excitonic line dependencies on the quantum well width and on the In percentage in
the quantum well were obtained. Also, we obtained the dependencies on the angle
of incidence of the exciting light and on the sample temperature. As a standard
procedure of characterization the mapping of the spectral properties of each sample
was carried out.
Advantages of this method in comparison with the photoluminescence are the
possibility of a simple experimental determination of the reflection peak broadening;
coherence of reflected signal; relative simplicity, clarity and uniqueness of the
resulting spectrum.
References
1. Poltavtsev S.V. et al. // Optics and Spectroscopy 105 (4), pp. 511-516, (2008).
164
On the determination of three-photon ionization
probability of Xe atom
Sanina Elizaveta
[email protected]
Scientific supervisor: Dr. Mityureva A.A., Department of Optics,
The measurement of magnitudes ratio between three-photon ionization
and ionization by electronic impact of Xe atoms is lead. The studied threephotonionization process passed through an intermediate two-photon resonance.
Experiment was made on the installation with supersonic beam of Xe/He gasmixture
and crossed laser and electronic beams.
165
Study of the vibrational spectrum of solid and liquid
sulfur
Savel'eva Svetlana
[email protected]
Scientific supervisor: Dr. Kolomiitsova T.D., Department of
Molecular Spectroscopy, Faculty of Physics, Saint-Petersburg
State University
The matrix isolation method is widely used for solution of the fundamental
and applied problems associated with the study of unstable molecules and radicals.
It is of interest to examine the possibility of using sulfur as a host medium for
recording the infra-red spectra of matrix-isolated compounds. Samples of eightatomic orthorhombic sulfur was studied in the solid (polycrystalline and single
crystalline) and liquid (at T = 373 and 413 K) phases and dissolved in carbon
disulfide. The vibrational absorption spectrum of the S8 molecule has been recorded
and interpreted, and the characteristics of 12 bands in the region of 2000-400 cm-1
were determined. The results derived from our spectra are in agreement with the
experimental data available in the literature [1]. The spectra of the CS2, SO2, and
CH3CN molecules embedded into the matrix of crystalline and liquid sulfur were
recorded. The absorption bands of the studied molecules were observed among
the bands of sulfur. The positions of maxima of absorption bands of CS2, SO2, and
CH3CN were compared with analogous values of molecular spectra recorded in
the gas phase. Comparison showed that the band peaks are shifted by 10-20 cm-1
upon passage from the gas phase to a condensed phase. Consequently, sulfur is
sufficiently inert solvent and can be used in matrix isolation experiments.
References
1. Scott D.W., McCullough J.P., Kruse F.H. // J. Mol. Spectrosc., v. 13, p. 313,
1964.
166
Vibrational spectra of germane GeH4 and silane SiH4 in
low-temperature matrices
Savvateev Konstantin
[email protected]
Scientific supervisor: Dr. Shcepkin D.N., Department of Molecular
Spectroscopy, Faculty of Physics, Saint- Petersburg State
University
Infrared spectra of germane and silane isolated at low temperature in nitrogen
matrices have been investigated at 9 K. The spectra of GeH4 and SiH4 are similar
in the regions of stretching and bending vibrations. The use of an enriched
sample containing 88.10% of the main isotope 76Ge and 11.69% of 74Ge allowed
us to unambiguously interpret the infrared spectra and to explain the observed
phenomena.
We processed the spectra of GeH4 recorded in nitrogen matrices at concentrations
ranging from 1/7000 to 1/1000. The characteristics of the fine structure of the bands
observed against the background of a broad structureless band were determined.
In [1, 2] two bands were recorded in the infrared spectrum of gaseous germane
at 2110.73 cm−1 and 820.32 cm−1, respectively [1, 2]. The molecules have the Td
symmetry, and the reducible vibrational representation decomposes into irreducible
representations as follows:
Гv=A 1+ E + 2 ∗F2,
where A1 is the totally symmetric, E doubly degenerate, and F2 triply degenerate
representations. The triply degenerate vibrations are active. We observed three
bands in the stretching region of spectrum of matrix-isolated germane. The band
at 2120.5 cm−1 is associated with the forbidden v1 vibration [1]. Splitting of the
v3 band is explained by decreasing in a matrix the Td symmetry to C3V. The triply
degenerate vibration splits into totally symmetric and doubly degenerate modes,
both of which being active.
To model the spectra, we solved the inverse vibrational problem and obtained
a theoretical spectrum, which describes the experimental spectrum of the doubly
degenerate mode to within 0.2 cm−1 for frequency and 3-10% for the relative
intensity.
References
1. Lepage P. // Journal of Molecular Spectroscopy 89, 440-448 (1981).
2. Das P. P., Devi V.M., Rao K.N., Robiette A.G. // Journal of Molecular
Spectroscopy 91, 494-498 (1982).
167
Efficient generation of quasi-monochromatic X-rays
using superpower femtosecond laser pulses
Sedov Maxim, Goryaev Andrey, Shebarshin Pavel
[email protected]
Scientific supervisor: Dr. Venediktov V.Yu., Department of General
The advanced technology of short-pulse lasers now provides the opportunity of
building sufficiently compact lasers with moderate and high repetition rates. The
pulses generated by these lasers can be focused to reach high intensities on a solid
target, and the absorbed laser energy can be partially converted into X-ray radiation.
More specifically, such laser pulses can be used to realize high power X-ray pulses
of short duration. During the interaction between a high-intensity, ultra-short laser
pulse and a solid target, fast electrons are created at the target surface that then
penetrate the target where they generate Kα radiation and Bremsstrahlung. The
generated X-ray pulses offer the prospect of creating a cheap and compact X-ray
source, and thus provide a promising alternative to synchrotron radiation, e.g. for
material science and medical applications. Solid matter irradiated by an intense
short-pulse laser constitutes a high brightness line source and particularly Kα
emission. With an increase in laser intensity, we can expect efficient X-ray emission
in the 1–100-keV range with a pulse duration shorter than a few picoseconds. This
short incoherent but monochromatic X-ray emission synchronized with laser pulses
may be used for time-resolved measurements in various medical and material
processing applications.
The aim of the present work is to obtain monochromatic X-ray source based
on laser plasma and to study the possibility of increasing the conversion rate of the
laser pulse into X-rays through the use of nano-sized and shaped targets.
The significant progress in the present research has been achieved. Experimental
setup for investigations of femtosecond laser plasmas was created, with energy in
50-fs-pulse up to 10 mJ and with vacuum target chamber. Laser radiation intensity
in experiment is from 1015 to 2x1017 W/cm2 depending on the focal diameter.
Satisfactory agreement was demonstrated between experimental and theoretical
data on generation of quasi-monochromatic X-rays by laser pulses.
168
Fresnel Lens
Semenov Semen
[email protected]
Scientific supervisor: Prof. Tolmachev Yu.A., Department of Optics,
The Fresnel Lens is an optical device which functions are the same as for
traditional lens. But as opposed to ordinary lens, it has another configuration.
It consists of a great number of thin ring lenses which border one to another.
This configuration permits for sparingly use of the material of the lens. In its
primary idea, the Fresnel lens must produce the images of the same quality as the
traditional perfect lens. Moreover, the analysis of its general properties gave rise
for expectations of some aberrations improving.
The aim of present work is in the study of so-called apparatus function of the
Fresnel lens as a whole and in the simulation of functioning of the Fresnel lens of
given configuration. When speaking of apparatus function we assume the intensity
distribution in focal plane of the image of monochrome point object positioned at
infinitely large distance from the lens.
The study was divided into several stages. The preferable geometry parameters
were defined at the first stage. The geometry parameters of a lens are the main
focal length of the lens; the radius of the central part of the lens and the widths of
the ring lenses, all of them are assumed to be equal one another. At the next stage,
calculations are to be fulfilled of the apparatus function for the ideal Fresnel lens
and for the real one. The difference between those is in phases of waves coming
to the focal point, regularly phase distribution in the first case and random phase
in the second one. Further, the analysis of apparatus function was carried out.
As the main result of the study, the unordinary form of the apparatus function
was detected in comparison with the apparatus function of the traditional lens.
The calculations revealed existence of great side lobes of the intensity distribution
which amplitude reached more then 20 percent of the main pike.
Afterwards, the Fresnel lens of predesigned form was considered. The
parameters of the lens were as following: focal length 11 mm, radius of central
lens 0.02 mm, widths of the ring lenses 0.2 mm, total number of rings 30.
For this lens, the simulation of spatial intensity distribution of the image formed
in the focal plane was realized. As the results of simulation, images of one, two
and three lines were obtained. Those lines were the white rectangles of given sizes
at the black background. The preliminary analysis of the results shows strong
degradation of the image contrast due to effect of side lobes.
169
Laboratory prototype of holographic display, optimized for
humane eye observation
Sevryugin Alexander, Pasechnik Irina
[email protected]
Scientific supervisor: Dr. Venediktov V.Yu., St.-Petersburg State
Electrotechnical University
Fig. 1.
The problem of holographic display, providing real 3D imaging of real or
imaginary objects by means of holographic reproduction has a long story of
discussion and investigation. Recently the technique was strongly pushed forward
by arrival on the market of the computer-controlled liquid crystal matrix phase
arrays. Such elements, in particular that of HOLOEYE Photonics AG (http://www.
holoeye.com/) production provide the possibility to record efficient thin phase
holograms.
Optimization of holographic display performance requires account for the
human eye properties, i.e. limited size of its pupil and its position with respect to
the display.
We report first results of laboratory testing of such a system prototype (see
Fig. 1). We have used the transmission type element Holoeye LC-2002 (600x800
pixels, 21x26 mm clear aperture). It was illuminated by the collimated plain beam
of He-Ne laser (633 nm). The computer hologram has reconstructed the virtual
(imaginary) image, which was observed by experimentator eye, positioned at
the distance ~1500 mm from this image. For recording the image we have used
the high-quality professional digital camera, whose lens pupil size was manually
controlled.
The structure of hologram was calculated with the use of the proprietary code
with account for the real human (or photographic lens) pupil diameter of 3-4 mm.
From the optical point of view this pupil has served as a field aperture, extracting
from the overall diffracted field the proper image, predetermined for observation
by eye in this position. The experiments have confirmed the expected behavior
of the system.
170
Wide aperture source of spatially coherent white light
Shalymov Egor, Gorelaya Alina, L’vova Alyona, Sedov Maxim
[email protected]
Scientific supervisor: Dr.Venediktov V.Yu., St.-Petersburg State
Electrotechnical University
a)
b)
Fig. 1.
Characterization and investigation of laboratory prototype of stellar
interferometer requires using of star simulator. Usually the point source of the
white light is enough, but in some cases, and, in particular in the case of testing of
prototype of stellar interferometer for celestial sphere mapping (OZIRIS Project,
see, for instance, [1]), one needs to use the spatially coherent plain wave of white
light with the sufficiently wide aperture.
We report the experimental verification of such a white light source (see Fig. 1a),
realized on the base of wide aperture refraction collimator with the achromatic
triplet lens (clear aperture 150 mm, focal length 1600 mm) from the optical bench
kit OSK-2. The primary source of the white light was provided by the standard
small-aperture projector with the tungsten lamp and condenser from the same
optical bench kit. Its light illuminated the pinhole in the focal point of the lens.
The collimator was pre-adjusted to the plainness beyond the Rayleigh limit using
the laser radiation and the etalon plane plate.
Thus was obtained the plain white light beam with aperture 150 mm. The
beam with diameter 20 mm was extracted from the arbitrary zone of the said
wide aperture beam and sent to the Mach-Zehnder interferometer. The stable and
reliable white-light interference pattern was thus provided (see Fig. 1b), proving
thus that the rate of system chromatism is sufficiently low so as to preserve the
white light interference. On the next stage of work it is planned to realize the white
light interference of two beams from two different and arbitrary zones of the wide
aperture beam.
References
1. Smirnov M.A., Boyarchuk A.A., Barabanov S.I. et al. OSIRIS - The Russian
Space-borne Astrometric Interferometer / Proceedings from ASP Conference Vol.
194. Edited by Stephen Unwin and Robert Stachnik // ISBN: 1-58381-020-X
(1999), p. 376-380.
171
Hybrid genetic algorithm for the spectroscopic data
processing
Shaymukhametova Elvira
[email protected]
Scientific supervisor: Prof. Kamalova D.I., Department of
optics and nanophotonics, Institute of Physics, Kazan Federal
University
In experimental researches there are often complex spectral contours with nonresolved internal structure caused by the overlapping of nearby lines. Such spectra
without the further processing aren't informative, as the information can be received
from the individual components which are parts of the complex spectrum. In this
connection, there is a problem on finding of number of components, their forms,
width, amplitudes and positions in a scale of frequencies for separate components
of complex spectral contour. For decision of the specified problems John Holland’s
genetic algorithms (GAs) were offered [1]. GAs are the adaptive methods of search
which refer to stochastic methods. They are based on the principles of natural
selection of Ch. Darwin.
In the given work the hybrid algorithm on the basis of the continuous waveletanalysis (CWA) and genetic algorithms for decomposition of complex contours
is offered. Using the CWA allows one to define the number of components and
their positions which are the input parameters for work of GA. Using the offered
technique, we have been processed experimental spectra of the polymers and carried
out the decomposition on elementary components.
Fig. 1. Processing of experimental spectrum by the use of genetic algorithm.
References
1. Forrest S. Genetic algorithms: principles of natural selection applied to
computation // Science. – 1993. – V.261. – P. 872–878.
172
Effect of the imaginary part of nondiagonal elements of
the relaxation matrix on the rotovibrational band shape
Sinyakova Tatyana
[email protected]
Scientific supervisor: Prof. Filippov N.N., Department of
Molecular Spectroscopy, Faculty of Physics, Saint-Petersburg
State University
Studying of infrared (IR) molecule spectra has grate impotence for astronomy
and atmospheric science particularly for analysis of transmission of infrared
radiation in the atmosphere of the Earth and other planets. An effective band
shape theory equally with the data of positions and intensities of spectral lines are
necessary to calculate IR spectra. At gas pressure above tens of millibars collision
induced perturbations are the leading mechanism of the band shape formation [1].
At that case the band shape is a sum of Lorentzian line profiles with linear pressure
depended width and shift of line. Deviations of the band shape from the sum of
Lorentzian components (line mixing effect) are also observed in the region of the
line overlapping especially in the band wing region.
In impact approximation, the band shape depends on the relaxation matrix Г.
Diagonal elements of this matrix describe line widths and shifts; the line mixing
effect is determined by off-diagonal elements. Usually the off-diagonal elements of
Г matrix are considered as real [1], the role of their imaginary part was estimated
as negligible in [2]. In this study we analyze the importance of imaginary part
of nondiagonal elements of Г to band shape calculation using a strong collision
model with modified complex relaxation matrix. With this model, the band
shape calculations demonstrate that imaginary part of nondiagonal elements has
considerable influence on the band profile in the region of line mixing effect
manifestation. It is shown that relative line intensities and relative rotational
branch intensities become pressure depended if the imaginary part of nondiagonal
elements is accounted for. Our calculations applied to the CO 2 fundamental
vibrational bands show that considered effect becomes significant at gas pressure
above tens of bars. Particularly, it can appear in the shape of the CO2 bands in
Venus atmosphere spectra.
References
1. Hartmann J-M., Boulet C., Robert D. Collisional effects on molecular spectra.
Laboratory experiments and models, consequences for applications. Elsevier,
2008.
2. Kouzov A.P., Tokhadze K.G., Utkina S.S.// Eur. Phys. J. D, v. 12, p. 53,
(2000).
173
Thermo optical study of liquid-crystal polymer
Sitnikova Vera
[email protected]
Scientific supervisor: Prof. Dr. Pakhomov P.M., Physical Chemistry
Department, Faculty of Chemistry, Tver State University
Scientific and practical interest to thermotropic liquid-crystal polymers,
arisen last two decades, is dictated by an ability of creation of novel construction
materials combining unique properties of low-molecular weight liquid-crystals
and high-molecular weight compounds. It is known that properties of thermotropic
polymers depend on microstructure, concentrations and sizes of liquid crystal
domains. Attempt to apply IR spectroscopic approach developed for estimating
the sizes of pores, particles in composites and filled materials is done to investigate
microstructure of the thermotropic polymer.
The idea of the method consists in the analysis of scattering appeared in IR
spectrum of the sample, if definite conditions are performed: size of the scattering
particles should be in a range of ~ 1,4–25,0 µm, and there is some difference
between refraction indices of the polymeric matrix and filler particles, pores or
liquid crystal domains in this experiment.
The aim of this work is to analyze changes of concentrations and sizes of liquid
crystal domains and their size distribution in a sample during phase transitions.
The objects of the study are films of thermotropic polymer (poly-3, 3'-biphenylene(suberoil-di-4-hydroxybenzoate) received from 1 % solution of the polymer
in chloroform. The polymeric film was placed between two KBr windows in a
special temperature controled device and IR spectra of the sample were recorded
on FTIR spectrometer «Equinox 55» («Bruker») at heating from 22 to 190° C
and subsequent natural cooling till room temperature (22 °C). Spectral data were
analyzed according to the technique for the analysis of scattering effects. Sizes of
liquid crystal domains in the thermotropic polymeric films were also controlled
by the light microscope «Neophot 30».
It is established that during heating and subsequent cooling of the thermotropic
polymeric film a gradual increase of scattering is observed, that is caused by a rise
of liquid crystal domains concentration in the sample. The scattering occurs on the
individual crystals forming the liquid crystal domains, which sizes are in the range
of 2-5 µm as it is determined from the microscopic data. It is found out that heating
of the thermotropic polymeric sample leads to changes of transmission intensity
of a number of absorption bands and to shift of some of them. These changes can
be connected with stoichiometric changes of mesogenic units in the polymeric
molecules. Thus, the IR spectroscopic approach can be used for characterization
of thermotropic liquid-crystal polymer microstructure.
174
Observation of the fine structure for rovibronic spectral
lines in visible part of emission spectra of D2
Umrikhin Ivan, Zhukov Alexey.
[email protected]
Scientific supervisor: Prof., Dr. Lavrov B.P., Department of Optics,
Faculty of Physics, Sankt Petersburg State University
For the first time the fine structure of rovibronic spectral lines in visible part
of emission spectra of D2 molecule has been observed. The capillary arc discharge
plasma in pure deuterium was used as a source of radiation (current dencities
were 0.24 - 17 A/cm2, gas temperatures 300-1500 K). Detailed description of the
experimental setup and characteristics of the spectrometer were reported in [1]
(maximum resolving power of up to 2*105, linear dispersion 0.077–0.065 nm/mm,
dynamic range of measurable intensities >104).
The vacuum wavelength values from [2] were used as wavelength standards
for the calibration of our spectrometer. Those values show certain spread around
monotonic dependence of the wavelength on the distance along the direction of
dispersion on CMOS matrix detector. The dispersion function was obtained by the
polynomial least-squares fitting of the wavelengths versus the distance for strong
unblended lines. Such wavelength calibration allows us to get new experimental
values for the wavenumbers of D2 spectral lines.
The digital intensity registration providing linear response of the CMOS matrix
detector gave us the opportunity for digital deconvolution of the recorded spectra.
For small regions of the spectrum (≈1.6 nm wide) the observed intensity distribution
was approximated by superposition of a certain number of Voight profiles with
half-width equal for all the profiles in studied spectral region. Optimal values for
adjustable parameters (intensities and centers of lines) were obtained by solving
the reverse spectroscopic problem in the framework of maximum-likelihood
principle by means of special computer program based on Levenberg–Marquardt 's
algorithm.
An analysis of the observed fine structure is illustrated on an example of the
R-branch lines for the (1-1) band of the i3Πg-→c3Πu- electronic transition. The
results concerning multiplet splitting in the c3Πu- state are in good accordance with
those earlier obtained by means of infrared FTIR and laser spectroscopy. Relative
intensities of the fine structure components are in agreement with our calculations
of adiabatic line strengths for Hund’s case “b” coupling scheme.
References
1. Lavrov B.P., Mikhailov A.S., Umrikhin I.S. // J. Opt. Technol., v. 78, I. 3, p.
180, (2011);
2. Freund R.S., Schiavone J.A., Crosswhite H.M. // J. Phys. Chem. Ref. Data.
V.14. \No 1. P. 235, (1985).
175
Determination of the isotopic composition and
thicknesses of thin targets
Vorotynskiy Andrey
[email protected]
Scientific supervisor: Dr. Lazarev V.V. , Department of Nuclear
It is possible to use inelastic scattering of alpha particles on nuclei with their
following decay into different final states to learn some properties of highly exited
states of light nuclear systems.
Particularly, it is proposed to make a correlational experiment with researching
the decay of an excited states of 12С nucleus into three alpha particles. The aim
of the experiment is the determination of the decay channel in dependence of the
excited energy. The results of this experiment will give us an opportunity of making
the conclusion about presence or absence of alpha particle Bose-condensate in the
nucleus, about the momentum distribution of alpha-particles and it will also help
us to examine the applicability of quasi-molecular description of light nuclei. The
energies of alpha-particles after the decay of excited nuclei 12С with the coincidences
with scattered alpha particles are measured in the experiment. There are three
possible channels of decay: the uncorrelated decay into three alpha-particles
without any intermediate nucleus, the decay of Bose-condensate and the two-step
decay through the intermediate nucleus 8Ве in basic or first excited 2+ state. It was
shown [1], that different alpha-particles from the decay have different energetic
and angular distribution depending on the configuration of the excited state.
My part of this experiment was to create the installation that will be able to
help us to determine the energy of cyclotron beam, to measure the thicknesses of
thin carbon targets and to determinate the isotopic composition of those targets
and to do the measurements.
References
1. Moiseev A.A. Shemes of nuclide decay. Energy and intensity of radiation.
Publication 38 of ICRP in two parts, Moscow, Atomenergoizdat 1987 pages 218231, 354-379.
2. Denisov A.E. PhD dissertation.
176
FTIR study of hydrogen bonded complexes of
phosphinic acid with different acceptors in the gas phase
Zakirov Ildar
[email protected]
Scientific supervisor: Dr. Asfin R.E., Department of Molecular
Spectroscopy, Faculty of Physics, Saint-Petersburg State
University
The IR spectra of mixtures in the gas phase phosphinic acid (H2POOH)
with deuterated acetone-D6, diethyl ether are recorded with Bruker IFS125
HR spectrometer with resolution 0.5 см-1 at different pressures at the room
temperature. The bands of the complexes were obtained by successive subtraction
of the phosphinic acid monomers and acceptors spectra from recorded ones. The
complexation were detected mostly by the shift of ν(P=O) band. The shifts of the
band relative to the corresponding phosphinic acid monomer one are compared
with shifts of the ν(C=O) band in the IR spectra of complexes trifluoracetic acid
and the same hydrogen acceptors.
177
G. Theoretical, Mathematical
and Computational Physics
Conservation laws and energy-momentum tensor in
Lorentz-Fock space
Angsachon Tosaporn
[email protected]
Scientific supervisor: Prof. Dr. Manida S.N., Department of High
Energy and Elementaty Particles Physics, Faculty of Physics,
In this paper we consider the conservation laws for classical particles in AdS4.
At first we parameterize a geodesic line and construct conserved quantities with
analog of five dimensional Minkowski space M(2,3). Consequently we change
AdS4 space to AdS-Beltrami space and write out conserved quantities in Beltrami
coordinates. Furthermore we take a limit for small velocity dxi/dt ≪c and we get
the conserved quantities in Lorentz-Fock space. And finally the energy-momentum
tensor for the dust matter is constructed.
References
1. Cacciatori A., Gorini V., and Kamenshchik A. // Special Relativity in the 21st
centuty, hep-th/0807.3009,(2008).
2. Manida S. Fock-Lorentz transformations and time-varying speed of light, grqc/9905046, (1999).
180
Mathematical modeling of the Casimireffect based on
the discrete sources method
Baryshev Alexandr
[email protected]
Scientific supervisor: Dr. Eremin Yu.A., Department of
Mathematical Physics, Faculty of Computational Mathematics
and Cybernetics, Lomonosov Moscow State University
The problem of evaluating the Casimir force has become a subject of interest
quite recently although it was predicted by Hendrik Casimir more than sixty years
ago in 1948 [1]. But first accurate experimental verification of the Casimir force
was first reported only in 1997 [2]. The Casimir force is a tiny force among chargeneutral bodies and is attributed to the quantum fluctuation of the electromagnetic
fields in vacuum. The force exists even when the field between the bodies is zero
in the classical sense and becomes the dominating interaction between neutral
bodies only at submicron distances, because it decreases rapidly with the separation
between the interacting bodies.
It is of great practical importance to investigate the Casimir effect for a number
of reasons.
The Maxwell stress tensor approach [3] is one of the most popular ways to
calculate the Casimir force. In the frame of that approach the force exerted on a
body from the other particles in the system can be expressed as an integral of the
mean electromagnetic stress tensor over any closed surface enclosing the body,
integrated over all frequencies. As a result of fluctuation-dissipation theorem the
terms of the Maxwell stress tensor, which are the mean fluctuating fields, can be
expressed via the imaginary part of the Dyadic Green's (DGF) function of the
considered system of particles. The DGF can be evaluated by the means of classical
numerical methods in computational electromagnetics.
The Discrete Sources Method (DSM) [4] is one of the most flexible and
powerful methods in classical electromagnetics. Compared to other methods the
DSM allows one to estimate a posteriori residual of the boundary value problem
(BVP) for the Maxwell equations.
The aim of the work is to implement the DSM to calculate the DGF for a system
of two metallic spheres and then to calculate the Casimir force according to the
Maxwell stress tensor approach.
Some numerical results are going to be presented during the conference.
References
1. Casimir H.B.G. // Proc. K. Ned. Akad. Wet. 51, 793 (1948).
2. Lamoreaux S.K. // Phys. Rev. Lett. 78, 5 (1997).
3. Rodriguez A.W., Johnson S.G. // Phys. Rev. A. 76, 32106 (2007).
4. Doicu A., Eremin Yu.A., Wriedt T. Acoustic and Electromagnetic Scattering
Analysis Using Discrete Sources. Academic Press, 2000.
181
Renormalization – group functions as convergent
integrals
Batalov Lev
[email protected]
Scientific supervisor: Dr. Adzhemyan L.Ts., Department of
Statistical Physics, Faculty of Physics, Saint-Petersburg State
University
A renormalization-group analysis in critical behavior problems explains a reason
of critical scaling and correctives in Landau's canonical exponent [1].
We concider a simple standard φ4 model. It describes a phase transition of
second kind in any system with one-component order parameter φ(x) and symmetry
φ→-φ.
A purpose of this work is calculation a critical exponent of φ-4 theory. The
critical exponent is expanded in series in the parameter ε=4-d. This way, provided
implementation of renormalization-group analysis makes the problem calculation
of converegent integrals. These integrals have a high multiplicity, and we can use
IBM to calculate them.
Surface divergences for large values of momentum (ultraviolet divergences)
at d=4 there are in the diagrams 1-irreducible Green's functions Г2 and Г4. These
functions have quadratic and logarithmic divergence respectively.
Renormalization procedure guarantees reduction of these divergences in each
order of perturbation theory.
An operation of extraction divergent parts is scheme of subtractions at
zero momentums. It has additional condition fixing the temperature in point of
normalization - NP. The scheme is subtraction of the sub-graph initial set of
terms of a Taylor series on the external momentum (it flows in sub-graph). The
temperature is fixed.
Anomalous dimensions were represented as these renormalized diagrams
simply way [2]. We used theorem of the absence of poles in epsilon ε=4-d for
renormalization-group functions.
The modified algorithm Vegas conducts integration. It is multidimensional
Monte-Carlo method. It breaks the region of integration down on hypercubes and
adapts grid at each iteration.
We calculated critical exponent in the three-loop approximation. It means that
critical exponents were represented as segments of the series in powers ε3.
References
1. Vasil’ev A.N. The Field Theoretic Renormalization Group in Critical Behavior
Theory and Stochastic Dynamics. - London: A CRC Press Company, 1998.
2. Adzhemyan L.Ts., Antonov N.V., Kompaniets M.V., Vasil'ev A.N. // Internat.
J. Modern Phys. B, 17, 10 (2003), 2137–2170.
182
Integration of UrQMD event generator with package
ROOT
Bondarenko Artem
[email protected]
Scientific supervisor: Dr. Nemnyugin S.A., Department of
State University
There are a large number of particle accelerators with different energies. Some of
the energy and states of matter, which is obtained at these energies are very poorly
studied. These are energies of about 10 GeV and mixed hadron state of matter - the
so-called quark-gluon plasma. The project NICA (Nuclotron based Ion Collider
fAcility) of Joint Institute for Nuclear Research in Dubna, is designed to observe
processes occurring in the mixed state of matter and with high baryon density [1].
There is a need in calculation of parameters of the MPD detector, which will be
used in this accelerator. A lot of scientific results in the high-energy physics were
obtained as a result of simulations with a package ROOT. But this package does not
provide tools for the calculation of the baryon density and many other parameters
of the collisions of heavy particles.
The aim of this study was to integrate the generator UrQMD [2] with package
ROOT. Writing a wrapper class on C++, changing the configuration file of ROOT, to
automatically build the whole package and validation of the data. UrQMD generator
allows one to calculate many unique characteristics of the collision, including a
history of the interaction of secondary particles and baryon density of secondary
events. The integration of the generator allowed to simplify and speed up many
calculations, such as reconstruction of particle tracks in the detector. The processes
occurring at high baryon density are interesting because some of the fundamental
laws are violated. One of them is a phenomenon of color superconductivity at high
baryon density [3]. The particular interest is represented by a problem of modeling
of such state. Calculation of some parameters of detector MPD (Multi-Purpose
detector) and the decision of other problems for project NICA will be the further
development of work.
References
1. Kenji Fukushima, Tetsuo Hatsuda // Rep. Prog. Phys. 74 p. 3 (2011).
2. Bleicher M., Zabrodin E., Spieles C. // J. Phys. G: Nucl. Part. Phys. 25 (1999)
1859-1896.
3. Alford M., Rajagopal K., Schafer T., Schmitt A. // Rev. of Mod. Phys., 80, 1455
(2008).
183
Ionization probabilities in low-energy heavy-ion
collisions
Bondarev Andrey
[email protected]
Scientific supervisor: Prof. Dr. Shabaev V.M., Department of
Quantum Mechanics, Faculty of Physics, Saint-Petersburg State
University
Heavy-ion collisions provide a good tool for tests of quantum electrodynamics
in extremely strong electromagnetic fields [1].
The field strengths achieved in heavy-ion collisions can well exceed the critical
value Zc ≈ 173, that corresponds to diving the lowest-energy bound quasi-molecule
state into the negative-energy Dirac continuum [2].
One may expect that the study of the ionization probability will allow us to
find a possibility to observe the diving phenomenon in low-energy heavy-ion
collisions.
In this paper the process of collision of the bare uranium nucleus with the
hydrogen-like uranium ion being in the 1s state is considered. The ionization
probability and the probability of conserving the initial 1s state are evaluated for
various values of the impact parameter and at the incident projectile energy equal
to 6 MeV/u.
In our approach time-dependent Dirac wave function is decomposed over the
basis of atomic orbitals and Sturm functions [3]. The time-dependent Dirac equation
is solved employing the exponential evolution operator method. The potential of
the projectile particle is accounted for within the monopole approximation, i.e.
only the spherical part of the potential is included.
As the next step the formalism developed will be extended to calculate the
ionization probabilities in collisions of heavy ions with neutral atoms. These
calculations are closely related to current experiments at GSI (Darmstadt).
References
1. Greiner W., Muellerand B., Rafelski J. // Quantum Electrodynamics of Strong
Fields. Springer, Berlin, Heidelberg (1985).
2. Proceedings of the Memorial Symposium for Gerhard Soff / Edited by W.
Greiner and J. Reinhardt, EP Systema, Budapest, (2005).
3. Tupitsyn I.I. et al. // Phys. Rev. A 82, 042701 (2010).
184
The influence of molecular clusterisation on vibration
spectrum of methanol
Borzda Tania
[email protected]
Scientific supervisor: Prof. Pogorelov V.Ye., Department of
Experimental Physics, Faculty of Physics, Kiev National Taras
Shevchenko University
The subject of research in this work is manifestation of intermolecular hydrogen
bond in vibration spectrum. As subject of research was taken the simplest of alcohols
- methanol. Urgency of work caused by the big role played by hydrogen bonding
in structuring the most important for human fluids - water, natural physiological
fluids, etc. Feasibility studies to select items based on the fact that methanol is
the simplest one internal fluid molecular hydrogen bonds. Analysis of vibrational
spectra of methanol, which contained molecules in crystalline argon matrix leads to
the conclusion that with increasing temperature argon matrix increases the number
of methanol molecules, which form cyclic clusters. In the frequency domain,
where the apparent valency OH group vibrations can be observed vibrational
bands associated with the dimer, trimmers, and tetrameter. Quantum-chemical
simulation for methanol molecule and clusters up to tetramer were carried out.
The calculations was based on the density functional theory in approximations
of bi-exponential atomic basis 6-31G (d,p), the hybrid exchange three-parameter
Becke potential and exchange-correlation Lee-Yang-Parr potential (B3LYP). The
results of quantum chemical calculations of model spectra correlate with these
findings. It is shown that intermolecular hydrogen bonding leads to changes of all
vibrational spectra of methanol. In particular, undergo significant changes contour
strips that related to valence vibrations of C-O bond. With increasing temperature
argon matrix from 15 to 50 K observed structures and expanding the disappearance
of C-O vibrational bands. A similar result is fixed in frequency domain vibrational
spectra of methanol, which manifested O-H valency vibration. In this temperature
can be argued that in the matrix remain only four-and five-moleculars clusters.
Methanol in the vibrational spectra of argon matrices at such temperatures similar
to the spectra of liquid methanol. From this you can infer that in both cases were
identical with the cluster structure.
185
Surface states in half-infinite superlattice with rough
boundary
Bylev Alexander
[email protected]
Scientific supervisor: Prof. Dr. Kuchma A.E., Department of
Statistical Physics, Physical Faculty, Saint-Petersburg State
University
Boundary between solid body and vacuum or other media could be a source
of special energetic states of electrons, called surface states. Surface states are
spatially localized near the bound of the body. Possibility of existence of such
states was studied in [1].
In this paper we studied surface states in half-infinite superlattices.
Superlattices are referred to call solid body structures with additional periodic
potential with bigger period than period of a crystal lattice. Parameters of
superlattice potential could be widely changed, due to it is possible to controllable
change band structure of a spectrum. Superlattices were discovered early in the
20th century and were theoretically studied in [2]. Now superlattices are widely
used in electronics and optics.
In general case surface is not a sharp change from nonpertubative periodic
potential to the outer space. It’s also necessary to take in to a count, that surface
might be covered by adsorbent layer. This kind of roughness will cause scattering
of a surface wave, which is an electron surface state, on the surface roughness.
This scattering will also cause transformation of a surface wave to volume wave.
It’s interesting to estimate damping of a surface state caused by this scattering.
In this paper was made analysis of influence of roughness of superlattice
surface on a surface state of electrons using simple one-band approximation for
nondegenerate bands of a crystal lattice. Superlattice was modeled by δ - like
potential wells, surface potential well had different depth than other potential
wells and roughness was modeled by dependence of surface potential power on
coordinates in surface plane [3].
It was shown that wave function of surface state will decrease in spreading
direction as a result of scattering on roughness and transformation to volume
Bloch-waves spreading inside the superlattice. Equations for coefficient of damping
of surface state in longitudinal direction were derived; contributions caused by
scattering on the surface and by transformation of surface wave to volume wave
were distinguished; numerical calculations of this coefficient were carried.
References
1. Tamm I.E. // J. of Experimental and Theoretical Physics, 1933, v.3, p. 34.
2. Keldysh L.V. // Solid body physics, 1962, v.4, p. 2265.
3. Kuchma A.E., Kovalevsky D.V., Voronin N.V. St.-Petersburg State University
Bulletin, series 4.2008. N. 4. p. 3-15.
186
Modelling of thermal-hydraulic processes in complex
domains by conservative immersed boundary method
Chepilko Stepan
[email protected]
Scientific supervisor: Yudov Y.V., Alexandrov Research Institute
of Technology
Today main approach within Computational Fluid Dynamics (CFD) for
numerical flow simulations in domains with complex boundaries is so-called
boundary-fitted methods on unstructured grids. For example, they are realized
in most widely used CFD-codes such as ANSYS CFX/Fluent and Star-CD. But
in recent decade there is a growing interest in developing of alternative so-called
immersed boundary methods on Cartesian grids. The aim of present work is
realization of conservative Cartesian cut-cell immersed boundary method based on
developing of work [1] for modelling of two-dimensional viscous incompressible
laminar flows of Newtonian fluids in Boussinesq approximation.
Spatial discretization of Navier-Stokes and heat transfer equations is performed
by finite volume second-order accurate method on collocated Cartesian grid.
Temporal discretization is accomplished by two-step fractional step procedure.
Convective and diffusive terms are approximated explicitly while pressure gradient
one - implicitly. Pressure Poisson equation is solved by direct linear equation
solver. Problem of possible unphysical pressure on collocated grid is overcome by
introduction of conservative face-center velocities field. Two-dimensional domains
boundaries are modelled by piecewise linear segments. Based on this representation,
cells in the Cartesian mesh that are cut by the boundary are identified and its
shape is determined, resulting in formation of computational control volumes set,
consisting of rectangular interior cells and trapezoidal ones near the boundary.
Small cut cells are absorbed by neighboring fluid cells by cell-merging technique
for eliminating of numerical instability of the solver. The key aspect of immersed
boundary solver is an accurate discretization of governing equations at cut cells,
which is achieved by applying of second-order accurate interpolation stencils,
slightly modified as offered in [1].
Accuracy and fidelity of the programmed solver is validated by simulating a
number of benchmark laminar flows including natural convection in closed cavities
and the ability of the solver to simulate flows with arbitrary complex boundaries
is demonstrated.
References
1. Ye T., Mittal R., Udaykumar H.S., Shyy W. // Journal of Computational Physics,
v. 156, pp. 209-240 (1999).
187
Development of functional integration techniques for
drift-diffusion processes on Riemannian manifolds
Chepilko Stepan
[email protected]
Scientific supervisor: Dr. Dmitrieva L.A., Faculty of Physics, SaintPetersburg State University
At present time mathematical foundations of functional integration (FI)
application for variable coefficients drift-diffusion processes cannot be considered
as complete, self-consistent and constructive. Moreover, there exists a deep gap
between theoretical physicists, who successfully use the so-called path integrals
as a formal tool, and mathematicians, who obtain different exact FI results which
sometimes do not match with that of physicists. In present work we try to build
some bridges gluing all known approaches together to get a unified construction
of FI representation for a solution of most general problem of drift-diffusion on
Riemannian manifold.
Starting from general non-linear Ito stochastic process, which defines geometry
of certain Riemannian manifold, one could introduce evolutionary families of
operators on functions and measures. Generators of these families define backward
and forward Kolmogorov PDEs of parabolic type. Fundamental solution of
backward Kolmogorov equation specifies related backward and forward transition
probability densities, which generate system of finite-dimensional distributions
of stochastic process. This system may be uniquely continued to functional Ito
measure. So solution of Cauchy problem for evolutionary equation under some
conditions could be represented as Lebesgue functional integral over Ito measure
[1]. On the other hand, more productive approach is a construction of the path
integral as a limit of finite-dimensional integrals by means of approximating families
of kernel operators [2]. Chernoff’s theorem postulates equivalence of some set of
operator families, which have the same generator as given evolutionary equation,
and states convergence of the product of short-time operators to the evolution
semigroup. This product gives rise to finite-dimensional discrete time integral
approximation to the solution of Cauchy problem and defines so-called action
functional on discrete sampling paths, depending only on covariant geometric
objects. The present paper deals, in particular, with a connection of both pictures
together and fixing an ambiguity in short-time path integral discretization [3] in
such a way, that both integrals will coincide.
References
1. Daleckiy Ju. // Mathematical Analysis (Russian), pp. 83–124 (1966).
2. Smolyanov O., Weizsacker H., Wittich O. // arXiv:math/0409155v3 (2008). 3.
Kleinert H. Path integrals // World Scientific (2009).
188
Calculation of one-particle green's function in extended
koopmans' approximation
Demidov Iurii
[email protected]
Scientific supervisor: Dr. Dmitriev Iu.Iu., Department of
University
In this work we calculate one-particle Green functions according with general
methodology of the Extended Koopmans’ Approximation [1]. And applied them
for calculation energy of molecule.
This algorithm for calculations of one-particle Green functions is illustrated
for molecules LiH and Hcl.
The Green’s function in extended Koopman’s approximation together with
the perturbation expansion of the irreducible mass-operator give a very important
instrumentation for practical usage, because this method can be applied for large
molecular systems.
References
1. Gusarov S., Fedorova T.A., Dmitriev Yu.Yu., Kovalenko A. // Internat. J.
Quantum Chem., 109, 1672-1675 (2009).
189
Multifractal generalization of the detrending moving
average approach to time series analysis
Ganin Denis
[email protected]
Scientific supervisor: Dr. Kuperin Y.A., Department of Nuclear
Physics , Faculty of Physics, Saint-Petersburg State University
The analysis of financial time series has been the focus of intense research
by the physics community in the last years [1, 2]. An important aspect concerns
concepts as scaling and the scale invariance of return fluctuations [3]. The aim
was to characterize the statistical properties of the series with the hope that a
better understanding of the underlying stochastic dynamics could provide useful
information to create new models able to reproduce experimental facts. It has been
recently noticed that time series of returns in stock markets are of multifractal
(multiscaling) character. The detrending moving average (DMA) algorithm [4] is a
widely used technique to quantify the long-term correlations of non-stationary time
series. We develop multifractal detrending moving average (MFDMA) algorithms
for the analysis of one-dimensional multifractal measures and multifractal time
series, which is a generalization of the DMA method. The performance of the
elaborated MFDMA methods has been investigated using synthetic multifractal
measures, namely binomial measure with the parameter p=0.25, and fractal
Brownian motion with different values of the parameter H. We have found that
the estimated multifractal scaling exponent τ(q) and the singularity spectrum f(α)
are in good agreement with the theoretical values. It has been shown that the
MFDMA algorithm also out-performs the multifractal detrended fluctuation analysis
(MFDFA) [5]. The proposed MFDMA method was applied to analyzing the time
series of the DJIA Index and its multifractal nature has been detected.
References
1. Bouchaud J.P., Potters M. Theory of Financial Risk, Cambridge University
Press, Cambridge, 2000.
2. Mantegna R.N., Stanley H.E. An introduction to Econophysics, Cambridge
University Press, 1999.
3. Mantegna R.N., Stanley H.E. Scaling behavior of an economic index // Nature
376 (1995) 46–49.
4. Alssio E., Carbone A., Castelli G., Frappietro V. // Eur. Phys. J. B, 2002, 27,
197.
5. Kantelhardt J.W. et al. // Physica A, 2002, 316, 87-114.
190
Determination of the type of hydrogen bonded
formations which occur in higher alcohols by means
of vibrational spectroscopy and quantum-chemical
calculations
Golub Pavlo
[email protected]
Scientific supervisor: Prof. Pogorelov V.Ye., Faculty of Physics,
Kyiv National Taras Shevchenko University
The modern theory of liquids based on the fact that the structure and properties
of real fluids is largely determined by structural features of nanoscale particles and
the associative nature of the forces acting between them. It is known that these fluids
are formed three-dimensional structure, consisting of several molecules related
intermolecular hydrogen bonds - clusters. Special interest causes the system with
intermolecular hydrogen bonds, which include alcohols. Alcohols are amazingly
convenient object for studying hydrogen bonds. In contrast to more simple, but
completely unchangeable molecules of water, alcohols can be “fit” under the
necessary research by easy restructuring of the backbone to which the hydroxyl
group attached [1].
The study of alcohol clusters conducted mainly for alcohol which molecules
contain a small number of atoms: methanol, ethanol, n-butanol [2-4]. There are
two basic topology of formation in alcohols structures which are connected by
hydrogen bonds: formation of closed, cyclic clusters, when all hydroxyl groups
in the structure involved in the creation of hydrogen bonds, and chain clusters,
when one of the hydroxyl groups remain nonbonded on the “edge” of a cluster
[1]. Theoretical calculations and experimental studies prefer the formation of
cyclic clusters in the liquid phase [5]. However, similar cannot be say in the case
of higher alcohols, because long alkyl groups may prevent molecules to form a
compact structure.
In this work investigated such higher alcohols as heptanol and oktanol. Using
the methods of quantum-chemical simulation we managed to establish possible
structures arising from the molecules in the liquid phase and determine their
energies and spectra. For reasons of energy utility of structures and comparing the
calculated spectra with the experimentally obtained, it is determined the types of
clusters that exist in this alcohols.
References
1. Suhm M.A. // Advances in Chemical Physics, 142 (2009).
2. Zimmermann D., Haber T., Schaal H., Suhm M.A. // Mol. Phys. 99, 413–426
(2001).
3. Buck U., Etischer I. // J. Chem. Phys., 108, 1 (1997).
4. Coussan S., Loutellier A., Perchard J.P., Racine S., Peremans A., Tadjeddine A.,
Zheng W.Q. // J. Chem. Phys., 107, 17 (1997).
5. Ludwig R. // Chem. Phys. Chem. 6, 1369–1375 (2005).
191
Optimization of high energy physics simulator
MPDRoot
Kashirin Dmitrii, Blinnikov Oleg
[email protected]
Scientific supervisor: Dr. Nemnugin S.A., Department of
State University
This work covers the problem of performance of computing in High Energy
Physics Simulator MPDRoot. Project Nuclotron-Based Ion Collider fAcility
(NICA) developed in Joint Institute of Nuclear Research processes a big amount
of data from different detectors. High performance computing is necessary in dataanalysis of this kind. It necessary to processes each collision occurring in work of
collider in minimal time.
In present time there are a lot of simulators and data analysis frameworks
based on CERN Root framework. They use different methods of high performance
analysis of large amount of data. But these methods is not always suitable for any
cases.
In this work author describe analysis of performance of simulator and data
analysis framework MPDRoot based on Root that used in NICA. Using Intel
Amplifier 2011 and google-perftools was founded the problem sections of simulator
that located at Multi-Purpose detector in part of Time Projection Camera simulation.
Founded a solution that helps increase performance and reduce the time of analysis.
Also were found solutions for future reducing the computation time.
192
Propagation of photons and massive vector mesons
between a parity breaking medium and vacuum
Kolevatov Sergey
[email protected]
Scientific supervisor: Prof. Andrianov A.A., Department of High
Energy and Elementary Particles Physics, Faculty of Physics,
The problem of propagation of photons and massive vector mesons in
thepresence of Lorenz and CPT invariance violating medium is studied when the
parity-odd medium is bounded by a hyperplane separating it from the vacuum. The
solutions in both half-spaces are carefully discussed and in the case of space-like
boundary stitched on the boundary with help of the Bogolubov transformations
provided by the space-like Chern-Simons vector. The presence of two different
Fock vacua is shown and the probability amplitude for transmission of particles
from vacuum to parity breaking medium is calculated.
We have also found classical solutions and showed that the results are consistent
with ones obtained by canonical quantization formalism. In the cases, both of
entrance to and of escaping from parity-odd medium, the probabilities for reecting
and passing through were found for each polarization using the classical solutions.
Finally, the propagator for each polarization is obtained in the momentum space.
Boundary effects under consideration are of certain importance for registration of
local parity violation in the finite volume of heavy ion fireball and/or of a star with
cold axion condensate [1].
References
1. Andrianov A.A., Kolevatov S.S., Soldati R. Propagation of photons and massive
vector mesons between a parity breaking medium and vacuum // arXiv:1109.3440
[hep-ph] . ICCUB-11-166.
193
Diffraction approach to the quantum three-body
scattering problem
Koptelov Yaroslav, Timofeeva Daria
Scientific supervisor: Dr. Levin S.B., Department of Higher
Mathematics and Mathematical Physics, Faculty of Physics, SaintPetersburg State University
The three-particle quantum problem is relevant in many fields of physics:
plasma physics, nuclear physics, high energy physics.
The first aim of the work is to obtain the scattering matrix for the system of
three one-dimensional quantum particles, interacting by the rapidly decreasing pair
potentials and to verify its unitarity. The second one implies a complete numerical
description of the solution.
At the beginning it is given the description of the system. It was shown in [1,
2] that the asymptotic solution for considered system contains plane, spherical and
Fresnel’s waves. Fresnel’s waves also occur in the two-dimensional problem of the
plane wave diffraction by a system of semi-infinite screens. This analogy allows to
reduce the initial problem to the diffraction problem of plane wave passing through
the three intersecting infinite screens. Since diffraction occurs on infinite screens,
the scattering amplitude contains the regular and singular parts. Weak asymptotics
are used to find the singular part analytically, while the regular part is constructed
numerically. The search of the analytical part can be divided into two phases: finding
the scattering amplitude in sectors with delta-functional singularities and finding
the scattering amplitude in sectors where Fresnel’s waves are present. The wave in
each sector should be integrated with a smooth test function over angle. In sectors
with delta-functional singularities this integral can be evaluated immediatly, while
in the remaining sectors at first it’s needed to replace Fresnel waves by generalized
functions with correct asymptotic behavior in the weak sense.
The second part of the work is devoted to a numerical determination of complete
solution using Comsol 4.1 package. Schroedinger equation (H-E)ξ=Q[ψ1] with
discrepancy Q[ψ1] and Hamiltonian H, which includes the sum of pair potentials and
Laplace operator, is solved in the weak form. In this equation ψ1 is an asymptotic
solution for the system considered, and ξ is the difference between the exact
solution and the asymptotic solution. The total wave function which describes the
interaction of three-dimensional quantum particles with rapidly decreasing pair
potentials is constructed using ξ and ψ1.
References
1. Buslaev V.S., Merkuriev S.P. // Sov. Phys. Dokl. 14 1055-1057, 1969.
2. Buslaev V.S., Merkuriev S.P., Slavikov S.P. // Probl. Mat. Phys. 9 14-30,
1979.
194
Analytical solution of two-dimensional Scarf II model by
means of SUSY methods
Krupitskaya Ekaterina
[email protected]
Scientific supervisor: Pr. of Ioffe M.V., Department of High
Energy and Elementary Particle Physics, Faculty of Physics,
In one-dimensional quantum mechanics the importance of exactly solvable
and quasi-exactly solvable models has been stressed repeatedly. The approach
of supersymmetric quantum mechanics (SUSY QM) and, in particular, shape
invariance has been fully exploited for construction and investigation of such
models. Generating a partnership between pairs of dynamical systems allows us
to establish the solvability of one in terms of another by means of intertwining
relations with supercharges of first order in derivatives. The next step for SUSY
QM was investigation two-dimentional models and supercharges of second order
in derivatives. Only a few such models are now exactly solved or quasi-exactly
solved.
It is shown in our paper, that one more two-dimensional model can be solved
analytically by means of supersymmetrical separation. The potential of this model
is naturally associated with solvable one-dimensional hyperbolical version of
Scarf model (Scarf II). This potential was obtained recently among new twodimensional models with shape invariance property. Just this property allows to
solve the problems with the whole hierarchy of generalized Scarf II potentials.
Thereby, in our paper the Scarf II is completely solved analytically for the integer
values of parameter. The spectrum of each member of hierarchy of Hamiltonians
is nondegenerate. As a result, all energies of bound states were found, and the
analytical expressions for corresponding wavefunctions were obtained.
The complete analytical solution of this two-dimensional model, together with
generalized Morse model and generalized Pöschl-Teller model, demonstrates that
supersymmetrical approach is a powerful method to solve the problems which are
not amenable to conventional separation of variables.
References
1. Ioffe M.V.// SIGMA 6 (2010) 075.
2. Ioffe M.V., Nishnianidze D.N. // Phys. Rev. A 76 (2007) 052114.
3. Ioffe M.V., Valinevich P.A. // J.Phys.A 38 (2005) 2497.
195
Calculations of charge-transfer in U92+ - U91+ collision usingthe
finite basis set of Hermitian B-splines
Maltsev Ilya
[email protected]
Scientific supervisor: Prof. Shabaev V.M., Department of
University
Calculations of the charge-transfer probabilities in low-energy collision of
U92+ (as a projectile) and U91+ (as a target) are presented. The method is based on
numerical solving the time-dependent two-center Dirac equation using the finite
basis set of Hermitian B-splines in cylindrical coordinate frame. The motion of
the nuclei is treated classically. Starting with the 1s1/2 target state, the electron
wave function is calculated for all subsequent time points. The final wave function
contains the whole information about the process we are interested. The chargetransfer probabilities are calculated at the projectile energy Elab = 6 MeV/u for
various values of the impact parameter. The results of the calculation are compared
with recent calculations by our group [1] obtained within the approach employing
atomic-like Dirac-Sturm orbitals, localized at the ions. This work should provide a
new step towards investigations of the quantum dynamics in heavy-ion collisions
near the supercritical regime (see, e.g., [2] and references therein).
References
1. Tupitsyn I.I., Kozhedub Y.S., Shabaev V.M., Deyneka G.B., Hagmann S.,
Kozhuharov C., Plunien G., and Stoehlker Th. // Phys.Rev A 82, 042701 (2010).
2. Greiner W., Mueller B., Rafelski J. // Quantum Electrodynamics of Strong Fields.
Springer-Verlag, Berlin, 1985.
196
Effects of turbulent mixing on critical behaviour:
renormalization group analysis of the ATP model
Malyshev Aleksei
[email protected]
Scientific supervisor: Prof. Dr. Antonov N.V., Department of High
Energy Physics and Elementary Particles, Faculty of Physics,
Consistent quantitative description of the critical behaviour of various systems,
subjected to strong turbulent mixing, can be achieved within the framework of the
renormalization group (RG) method. In this work relaxational stochastic dynamics
of a non-conserved N-component order parameter, specifically the Ashkin-TellerPotts (ATP) model, is considered. The ATP model has attracted a great deal of
attention, due to the fact that it can describe a very rich class of physical situations.
For example, the N = 2 version of the model describes the transition of a liquid
crystal from its nematic to its isotropic phase [1]. The limit N → 0 can describe
the critical behaviour of bond percolation [2]. Turbulent mixing is modelled by a
random velocity field with prescribed statistics. The velocity is taken Gaussian,
white in time, with correlation function of the form ∝ δ(t-t′ )/|k⊥| d−1+ξ, where k⊥ is
the component of the wave vector, perpendicular to the distinguished direction
("direction of the flow")  the d-dimensional generalization of the ensemble
introduced in [3] within the context of passive scalar advection.
It is shown that, depending on the values of the parameters defining selfinteraction of the order parameter and the relation between the exponent ξ and the
space dimensionality d, the system exhibits various types of large-scale self-similar
behaviour, associated with different infrared attractive fixed points of the RG equation.
In addition to well known asymptotic regimes (Gaussian free theory, Potts model
critical dynamics and passively advected order parameter with no self-interaction),
existence of a new, non-equilibrium and strongly anisotropic type of critical behaviour
(universality class) is established, and the corresponding critical dimensions are
calculated to the leading order of the double expansion in ξ and ε = 6 − d (one-loop
approximation). The most realistic values of the model parameters (for example, d =
3 and the Kolmogorov exponent ξ = 4/3) belong to this new class (for both physically
interesting cases N = 2 and N → 0). The scaling behaviour appears anisotropic in the
sense that the critical dimensions related to the directions parallel and perpendicular
to the flow are essentially different. The results are in qualitative agreement with the
results, obtained in experiments and simulations of fluid systems subjected to various
kinds of regular and chaotic anisotropic flows.
References
1. De Gennes P.G. // Phys. Lett. 30A 5 (1969).
2. Fortuin C. M. and Kasteleyn P.W. // Physica 57 536 (1972).
3. Avellaneda M, Majda A. // Commun. Math. Phys. 131 381 (1990).
197
Inertial-range behaviour of a passive scalar field in a
random shear flow: renormalization group analysis of a
simple model
Malyshev Aleksei
[email protected]
Scientific supervisor: Prof. Dr. Antonov N.V., Department of High
Energy Physics and Elementary Particles, Faculty of Physics,
The mathematical techniques of quantum field theory, which were originally
invented for describing the interaction of relativistic elementary particles, proved
to be extremely useful in other areas of physics: solid state and condensed matter
physics, classical statistical physics (especially critical phenomena), stochastic
processes, fully developed hydrodynamical turbulence. In the present work
infrared asymptotic behaviour of a scalar field, passively advected by a random
shear flow, is studied by means of the field theoretic renormalization group and
the operator product expansion. The advecting velocity is taken Gaussian, white
in time, with correlation function of the form ∝ δ(t-t′)/k⊥d−1+ξ, where k⊥=|k⊥| and k⊥
is the component of the wave vector, perpendicular to the distinguished direction
("direction of the flow")  the d-dimensional generalization of the ensemble
introduced by Avellaneda and Majda within the context of passive scalar advection
[1].
The structure functions of the scalar field in the infrared range exhibit scaling
behaviour with exactly known critical dimensions. It is strongly anisotropic in the
sense that the dimensions related to the directions parallel and perpendicular to the
flow are essentially different. In contrast to the isotropic Kraichnan's rapid-change
model [2], the structure functions show no anomalous (multi)scaling and have
finite limits when the integral turbulence scale tends to infinity. On the contrary, the
dependence of the internal scale (or diffusivity coefficient) persists in the infrared
range, in contradiction with the classical Kolmogorov theory.
Generalization to the velocity field with a finite correlation time is also obtained.
Depending on the relation between the exponents in the energy spectrum Ε ∝ k⊥1−ε
and in the dispersion law ω ∝ k⊥2−η, the infrared behaviour of the model is given by
the limits of vanishing or infinite correlation time, with the crossover at ε =η. The
physical (Kolmogorov) point ε = 8/3, η = 4/3 lies inside the domain of stability of
the rapid-change regime; there is no crossover line going through this point.
References
1. Avellaneda M., Majda A. // Commun. Math. Phys. 131 381-429 (1990).
2. Gawedzki K. and Kupiainen A. // Phys. Rev. Lett. 75: 3834-3837 (1995).
198
Investigation of the mean field and excluded-volume
models in the kinetics of nucleation stage
Markov Maksim
[email protected]
Scientific supervisor: Prof. Dr. Kuchma A.E., Department of
University
In the present paper the approach to the kinetics of nucleation of supersaturated
vapor based on excluded-volume hypothesis is suggested. In contrast to the
traditional mean-field theory, the developing approach is based on assumption
that the nucleation of new droplets is essentially suppressed only in diffusion
layer around droplets which have been formed earlier, but that is stayed constant
outside. Using the results of self-similar theory of diffusion growth of individual
droplet the main characteristics of nucleation such as nucleation time, the amount
of droplets at the end of stage, the mean size of droplets and their size-distribution
are found. It is shown that for typical values of vapor parameters the results are
close to the results of classical approach based on assumption of space-uniform
distribution of vapor supersaturation which is decreasing monotonically in time
during nucleation. At the same time it is significant to point out the difference in
physical pictures of two approaches.
References
1. Kuni F.M. // Preprint ITF-83-79R (1983).
2. Kuchma A.E., Kuni F.M., Shchekin A.K. // PhysRev E №80, 061125 (2009).
3. Grinin A.P., Kuni F.M., Gor G.Yu. //Colloid. J, vol.71, №1, p.47-55 (2009).
199
Effects of Stefan’s flow and concentration-dependent
diffusivity in binary condensation
Martyukova Darya
[email protected]
Scientific supervisor: Prof. Kuchma A.E., Department of Statistical
The subject of this paper is studying the problem of droplet growth in the
atmosphere of two condensable vapors and noncondensable carrier gas. The results
of such study are essential for fundamental and applied problems of the theory of
decomposition of solid and liquid solutions, and the theory of phase transitions
in the Earth’s atmosphere. A typical example of binary condensation under the
conditions of the Earth atmosphere is condensation of water and sulfuric acid
vapor in rain drops.
The problem of the droplet growth and establishing the drop composition in
case of binary condensation has been considered in [1, 2] in the approximation
which neglects the Stefan flow and the dependence of the diffusion coefficients
on the composition of the vapor-gas mixture. In this paper, new expressions for
the fluxes of condensating vapors and the corresponding equations for the time
dependence of the droplet radius and its chemical composition are derived. These
expressions and equations take into account both Stefan flow and concentration
dependence of diffusion coefficients in an isothermal approximation. In particular,
it is shown that expressions for the contribution to the vapor flux associated with
the Stefan flow are different from those used in [3].
References
1. Kuchma A.E., Shchekin A.K, Kuni F.M. // Colloid Journal, V. 73, P. 215
(2011).
2. Kuchma A.E., Shchekin A.K., and Kuni F.M. // Physica A, Vol. 390, Issue 20,
P. 3308 (2011).
3. Kulmala M., Vesala T., Wagner P.E. // Proc. Royal Soc., Vol. 441, P. 589
(1993).
200
Application of 2D-correlation spectroscopy method for
interpretation of spectra and enhancing the spectral
resolution
Maximova Ekaterina, Derzhavets Lev
Scientific supervisor: Dr. Levin S.B., Department of Computational
The idea of 2D-correlation spectroscopy appeared not long ago, so the number
of publications in this field is not significant yet. 2D-correlation spectra consist of
two orthogonal components - synchronal and asynchronal spectra. Both of them
carry significant and independent information about the behavior of the studied
system.
The aim of current work is to make acquaintance with the 2D-method for
interpretation of spectra and enhancing the spectral resolution. Also, we considered
the continuous approximation of spectral amplitude two-dimensional surface
defined in the frequency-time surface:
I ( ν, t ) = Ω( ν) P (t ),
nν
where
− a ( ν − nu j )2
Ω( ν) = ∑ Aj e j
j =1
and
Bj
nt
P(t ) = ∑
j 2
2
j =1 (t − t0 ) + η j
This kind of approximation is convenient from the point of view of analytical
construction of 2D-correlation spectra. Furthermore, such a constructions will
give opportunity to interpret more effectively complex processes being under
study [1].
The aim of the current work is to construct two-dimensional correlation spectra
for unconditioned set of basis functions for two time experimentally obtained
dependencies for two frequencies. Correlations obtained by using the discrete set
of experimental data, proposed by Noda [2-3] are the additional criterion for the
quality of approximation.
References
1. Tonkov M.V., Filippov N.N. // Chem. Fizika, 10(7), 922, (1991)
2. Isao Noda, Yukihiro Ozaki. Two-dimensional Correlation Spectroscopu –
Applications in Vibrational and Optical Spectroscopy, England, 2004.
3. Noda I. // Appl. Spectrosc., 47, 1329 (1993).
201
The effective 8-spinors model of elementary particles
Molotkov Viacheslav
[email protected]
Scientific supervisor: Prof. Dr. Rybakov Yu.P., Department of
Theoretical of Theoretical Physicas, Faculty of Science, Peoples’
Friendship University of Russia
For unification of the Skyrme and the Faddeev models we consider the
electrodynamics of Mie within the scope of the effective 8-spinor field. For the
classification of all the possible chiral type models, the Brioschi identity is used
[1].
Including of Higgs-like potential Vand high degrees of the invariant AμAμ in
the Lagrangian [2]:
1 2
L = Dµ ψγ α jα D µ ψ − V ( jµ j µ ) −
Fµν − κAµ Aµ
16π
2
1 µ
V=
j jµ − κ 02 , κ 0 = const.
8
We receive the classification of the soliton configurations through a topological
charge.
The structure of the Lagrangian is investigated taking into account the given
theory.
The Euler-Lagrange equations are discovered evidently. The condition for
8-spinors is considered under the similar conditions for the Hydrogen-like
substitutions, which makes it possible to separate the contribution of angular
variables in the equations.
We consider leptons sector within the scope of the united model for an axiallysymmetric field. To this end the vacuum condition at a large distance (r→∞) is
analysed.
(
)
References
1. Cartan E. The theory of spinors.,Courier Dover Publications, p. 157 (1981).
2. Rybakov Yu.P. Soliton configurations in generalized Mie electrodynamics.(to
be published in Physics of Atomic Nuclei).
3. Rybakov Yu. P., Terlezki Ya.P. Quantum mechanics. PFUR (1991).
202
Magnetization reversal in spring magnets
Moskalenko Mary
[email protected]
Scientific supervisor: Prof. Uzdin V.M., Department of Statistical
Physics, Faculty of Physics, Saint-Petersburg State University;
Department of Higher Mathematics, National Research University
of Information Technologies, Mechanics and Optics
Most applications of magnetic nanosystems presuppose a transformation of
the magnetic state under the action of external magnetic field. The evolution of a
magnetic structure as a response to an external magnetic field can lead to a rich
variety of behaviors at the nanoscale. One of the model systems where non-collinear
structure can be continuously and reversibly modified by external magnetic field is
exchange-spring permanent magnets. These systems consist of exchange-coupled
hard and soft magnetic bilayers or multilayers. In external magnetic field the moments in the soft magnetic layers form the non-collinear spiral structures which
depend on the value and the direction of the field. Exchange spring media is one
of the promising technologies of high-density magnetic recording.
Modern theories developed for the description of magnetization reversal process
in spring magnets are based on one-dimensional phenomenological model of
exchange coupled spin chain and assume that all atoms in each layer are equivalent
[1]. Although such approach reproduces the general features of the remagnetization
process, it contains a large number of phenomenological parameters and, moreover,
these parameters depend not only on the material but on the conditions of sample
growth. Therefore interface roughness and interdiffusion occurring during the
epitaxial growth is very important factor which have to be taken into account for
adequate description of magnetization reversal process.
We developed the computer code which allows the self-consistent calculation
of exchange magnetic spring structure with non-ideal interfaces in external
magnetic field. For the case of smooth interfaces the results of standard models
[1] are reproducing. Different types of interface roughness are considered. It is
shown that the structure of the interface at atomic scale strongly influence on the
shape of hysteresis loop and other observable macroscopic properties. On this way
it is possible to connect the conditions of epitaxial growth with required for the
applications magnetic properties. The results of the calculations will be used for
development of more general approach based on the finite element method, which
will take into account demagnetization fields.
This work was partially supported by bilateral DFG-RFBR project (DFG ZA
161/20-1; RFBR 11-02-91337).
References
1. Fullerton E.E., Jiang J.S., Grimsditch M., Sowers C.H., and Bader S.D. // Phys.
Rev. B, 58, 12193 (1998).
203
A matrix approach for the dyadic Green's function in
multilayered elastic media.
Nikitina Margarita
[email protected]
Scientific supervisor: Dr. Val’kov A.Yu., Department of Statistics
Physics, Department of Physics, Saint-Petersburg State
University
The Green’s function method is widely used for studies of layered media [1, 2],
in particular for analysis of the synthetic seismograms.
In this paper the general expression for the harmonic Green’s function in
the mixed 1D-spatial and 2D-impulse Fourier representation for a locally isotropic layered elastic medium with properties arbitrary varying along the z-axis
is obtained
−1
−1
V ( z )V> ( z ') W ( z '), z ≥ z '
G ( z , z '; q ⊥ ; ω ) =  >
−1
−1
V< ( z )V< ( z ') W ( z '), z ≤ z '
Here
W ( z ) = K ( z )(V<′ ( z )V< ( z ) − V>′ ( z )V> ( z ))
is the matrix generalization of the Wronski matrix, and diagonal matrix K(z) is
determined by local material constants. The columns of 3x3-matrices V< and V>
are��
composed from ��
a complete set of six linear-independent��
vectors which are solutions, u<(2), u<(3) and u>(1), u>(2), u>(3) of the homogeneous elastic wave equation. The
first three solutions describe the waves propagating from the source z' to the left
direction and satisfy to the left boundary condition, and three others are the waves
propagating to the right direction satisfying to the right boundary condition.
Presently explicit analytical expressions for the normal modes u<(j)(z) in the
case of piecewise-homogeneous medium are derived. The method is based on a
matrix presentation of the boundary conditions. This gives a matrix recurrence
relationship between neighbouring layers for complex amplitudes of the six normal
modes of elastic fields.
The final formula for the Green’s function is contributed by the body waves,
transverse and longitudinal, and by surface waves of Rayleigh, Lamb and Stoneley
generated by the poles of the matrix Wronskian. This formula has been used for
numerical computation of the harmonic Green function in the layered media.
References
1. K. Aki and P. G. Richards , Quantitative Seismology, Theory and Methods, V.1:
W.H. Freeman and Co., San Francisco, 1980.
2. K. Wapenaar, J. Fokkema, // GEOPHYSICS, v. 71, Iss. 4, pp. SI33-I46 Suppl.
(2006); E. Liu, Z. Zhang, J. Yue and A. Dobson // Commun. Comput. Phys., v. 3,
pp. 52-62 (2008).
204
Detectable effects in classical supergravity
Niyazov Ramil
[email protected]
Scientific supervisor: Dr. Shadchin S.V., High Energy and
Elementary Particles Physics Department, Physics Faculty, SaintPetersburg State University
Supersymmetric theories and, in particular, supergravity manifest a symmetry
between fermions and bosons. Despite the popularity of such theories, they miss
experimental evidences. That’s why it’s important to search for possible experiments
to confirm these theories.
It appears that in classical supergravity it is possible to find such experiments
with a moving probe particle. In general relativity to describe the motion of a probe
particle around a black hole, the Schwarzschild solution can be used. General
Relativity (at least at classical level) can be seen as supergravity with vanishing
gravitino, superpartner of gravitons, described by Rarita-Schwinger field. This
fact in combination with the supersymmetry transformations of the Schwarzschild
solution can be used to obtain solution of classical equations of motion for the
graviton and gravitino in supergravity and therefore to find the supersymmetric
corrections to the space-time interval. This problem was investigated in the
paper.
Once the space-time interval is obtained, we are in position to compute the
supersymmetry corrections to the classical solutions of the probe particle equations
of motion and the light beam trajectory. It turns out that first order corrections (on
a suitable parameter) are not observable and can be eliminated by redefinition of
momentum and impact parameter for the particles, and for the light beam. Second
order corrections exist only for the motion of probe particle. Such corrections
appear in the anomalous displacement of perihelion of the probe particle The ratio
of these corrections and the standard General Relativity ones is proportional to the
square the constant characterizing the gravitino field and inversely proportional to
the square of the gravitational radius of the black hole.
Thus effects of second-order supergravity can be detected while observation
of probe particle perihelion displacement for the small black holes. To make effect
measurable, some conditions should be imposed to the laboratory system. The size
(according to calculations about 0.25 meter) and the weight (about 1 kilogram) of
this system are quite human-natural, but complete isolation of the laboratory from
external fields is required.
References
1. Baaklini N. Classical solutions in supergravity / N. Baaklini, S. Ferrara, P. van
Nieuwenhuizen // Lettere Al Nuovo Cimento (1971 - 1985). – 1977. – Vol. 20. –
Pp. 113-116. – 10.1007/BF02787025.
205
Calculation of characteristics of critical behavior in
logarithmic dimensions
Pismenskiy Artem
[email protected]
Scientific supervisor: Prof. Dr. Pis’mak Yu.M., Physical Faculty
of Saint-Petersburg State University
In our work we study the asymptotic behavior of Green functions for the theory
φ4 in a critical point by means of renormalization group equation and also by means
of self-consistent Dyson equation.
S=1/2 (∂φ)2 – λ/4! φ4.
Where φ is n-component vector field, λ is link constant.
We investigate infrared asymptotic of propagator in the logarithmic dimension
of space: d=4 for the φ4 theory.
Renormalization group equation gives the next result:
D(x)=A/p2 [1+O(1 / ln (p/p0))]
in momentum representation or
D(x)=A/x2 [1+O(1 / ln (x/x0))]
in coordinate representation.
We discuss the results received be the means of self-consistent equation.
We have shown that by using of self-consistent equation, we obtained the same
results more simply.
References
1. Vasil'ev A.N. The field theoretic renormalization group in critical behavior
theory and stochastic dynamics. SPb, 1998.
2. Okabe Y. Logarithmic Corrections to a Simple Power Law at d=4 in 1/n
Expansion. // Progress of Theoretical Physics, vol. 59, № 2, 1978.
206
Numerical solution of the non-stationary Dirac equation
for systems with axial symmetry
Rozenbaum Efim
[email protected]
University
The main goal of this work consists in obtaining numerical solutions of the
Dirac equation describing a hydrogenlike atom in presence of an external electric
field. The important property of the developed algorithm is its independence on
the spherical symmetry of the atom. It means that further improvements of this
algorithm will allow us to apply it to various atomic problems, including the
electron-positron pair production in the strong laser field.
The reasonable number of bound states is accurately described as a result of
using the proper numerical technique, namely the generalized pseudospectral
method [1]. The advantage of this method consists in the fast convergence and
the high numerical efficiency. This approach results in the transformation of the
equation into the matrix eigenvalue problem. The last one is solved with the standard
routine presented in the Intel Math Kernel Library.
The split-operator technique [1] is used in the case of the non-stationary Dirac
equation. It enables a great reduction in the system evolution calculations by
separating time-independent parts of the Dirac operator. Consequently there is no
need to recalculate them at every time step.
The relative errors in the representation of the energy levels are less than 10-8.
That’s why the relativistic corrections to the non-relativistic atom’s energies can
be easily noted in the obtained values.
References
1. Dmitry A. Telnov, Shih-I Chu // Phys. Rev. A 76, 043412 2007.
207
Investigation of Bragg peaks in heterogeneous biological
models
Ruban Olga
[email protected]
Scientific supervisor: Dr. Nemnyugin S.A., Department of
State University
Hadron therapy is a novel cancer treatment technology which uses beams of
charged hadrons, such as protons and carbon ions, to irradiate diseased tissues. It
employs the fact that the dose delivered to tissue is maximal just over the end of the
particle’s range; this maximum is called the Bragg peak [1]. Due to this effect, the
precision of irradiation and damage
to tumour cells considerably
increases, therefore decreasing
damage to healthy tissues and
allowing one to reduce the amount
of treatment sessions.
So complex and accurate a
technique requires a thorough
preparing, which must include
preliminary simulation of
processes in biological tissues
under irradiation. Beam parameters
must be selected considering the
geometry of affected organ, its physical properties and chemical composition.
The goal of present work is to investigate the Bragg peaks behaviour, using
Geant4 [2], one of the most popular toolkits for Monte-Carlo simulation of the
passage of particles through matter.
For simulation purposes, a homogeneous water phantom of simple shape is
usually used. In the present work, we made simulations for more complex and
close to real conditions models. The target cylindrical phantom consists of different
materials, representing human body tissues. Five main tissues were simulated:
skeleton, soft tissue, adipose, lung, and glandular tissues.
Obtained results include dependences of deposited dose on penetration depth,
particle type, and particle energy, as well as simulation of Bragg peaks behaviour
near boundary layers.
References
1. Camphausen K.A., Lawrence R.C. Principles of Radiation Therapy/ in Cancer
Management: A Multidisciplinary Approach. 11 ed. 2008.
2. http://geant4.cern.ch/
208
B-meson decay constant within QCD sum rules with
Modified correlator
Rusov Aleksey
[email protected]
Scientific supervisor: Dr. Parkhomenko A.Ya., Department of
Theoretical Physics, Faculty of Physics, Yaroslavl P.G. Demidov
State University
The study of B-meson physics plays a fundamental role both in accurately
testing the Standard Model and in search of new physics.For such purpose, it is very
important to determine different B-meson transition matrix elements with a high
accuracy. Especially, the leptonic decay constant fB, the matrix element between
the B-meson and vacuum, is of fundamental importance for B-decays.
The value of the decay constant fB can be derived from branching fractions of
pure leptonic decays of B-meson. At present, the decay B+→τ+ντ only is measured
experimentally by the BaBar and Belle collaborations (with hadronic and semileptonic
tag methods both) and the results obtained are in an excellent agreement between
each other. The averaged branching fraction Br(B+→τ+ντ)=(1.65±0.34) ×10-4 results
|Vub| fB= (0.97±0.10) MeV and a phenomenological extraction of fB strongly depends
on the value of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |Vub|.
Using the averaged value |Vub|=(3.92±0.45)×10-3‍one obtains fB= (249±38) MeV.
Among the purely theoretical methods for a calculation of fB the Lattice QCD
and QCD sum rules (QCD-SRs) are the most popular. In the conventional approach,
the estimates obtained are fB= (193 ±10) MeV (Lattice) and fB= (206±20) MeV
(QCD-SRs). These results are significantly smaller than the phenomenological
value but still consistent with it.
In the recent paper [1] the decay constant fB has been calculated to NLO by
applying the conventional QCD-SRs and the so-called chiral QCD-SRs. The
authors demonstrated explicitly that the use of the left-handed component of the
B-meson interpolating current only results both in increasing of fB and decreasing
its uncertainty.
We extend this analysis assuming that left- and right-handed components of the
B-meson interpolating current contribute differently to fB and the corresponding
asymmetry parameter is estimated by fitting the phenomenological value of the
decay constant fB= (249±38) MeV. The analysis shows a non-vanishing asymmetry
which origin is unclear within QCD. Converting this asymmetry into the admixture
of the vector component to the axial-vector B-meson interpolating current, the
best-fit prefers a dominance of the vector part.
References
1. Wu X.-G., Yu Y., Chen G., Han H.-Y. // Communications in Theoretical Physics
55, 635-639 (2011).
209
Triple differential cross sections for (e, 2e) ionization of
molecular targets
Shevyakina Natalya
[email protected]
Scientific supervisor: Dr. Yurova I.Yu., Department of Quantum
Mechanics, Faculty of Physics, Saint-Petersburg State
University
TDCS, a.u.
The most sophisticated experiments measure triple differential cross sections
(TDCSs) of different targets: atoms and molecules [1]. The importance of an
accurate evaluation of these cross sections is evident. Triple differential cross
sections bring the most detailed information about the dynamics of the (e, 2e)
reaction. Interactions of electrons with atoms and molecules are of interest in many
fields of science such as astrophysics, planetary and upper-atmosphere reactions,
radiation and plasma physics, etc. All these areas need a full understanding of the
mechanisms involved in electron-atom and electron-molecule collisions.
o
Here we report a
(e, 2e) H 2 : E e j = 5 eV, scattering angle -3 , diff. E in (eV)
30
theoretical
investigation
60
80
Molecular orientation (0 o , 0 o )
of the (e, 2e) ionization
100
25
150
process in a coplanar
200
plane geometry with
300
20
400
k in
a s y m m e t r i c e n e rg y
H
500
2
600
regime using electron
700
15
800
as projectile and
900
1100
molecular hydrogen
10
1300
1700
as target. Analytical
2200
3000
formula for (e, 2e)
5
ionization amplitude of
the hydrogen molecule
0
0
50
100
150
200
250
300
350
400
Ejection angle, deg
was obtained. Using
Fig. 1. Triple differential cross sections for (e, 2e) derived formula the
ionization of molecular hydrogen. For details see text. TDCSs for wide ranges
of kinematical parameters have been calculated. Figure 1 shows theoretical TDCSs
for electron impact ionization of H2 molecule in the coplanar plane geometry
for different incident electron energies, fixed ejected electron energy 5 eV, fixed
scattering angle -3º and fixed orientation of the molecular axis (0º, 0º). Some nonphysical structures were found in the resulting TDCSs. One of the aims of this
work was to make numerical calculations of discrete-continuous matrix elements
to improve these non-physical features in the resulting cross sections.
References
1. 1. O. Al-Hagan et al // Nat. Phys., v. 5, № 1, p. 59, (2009).
210
New embedding of the Schwarzschild black hole metric
Sheykin Anton
[email protected]
Scientific supervisor: Dr. Paston S.A., Department of High Energy
and Elementary Particles Physics, Faculty of Physics, SaintPetersburg State University
The history of study of Riemannian manifolds in terms of a flat ambient space
began from the Janet-Cartan theorem, which ensures that any N-dimensional
manifold can always be locally (and sometimes global) embedded in a flat space
of dimension N(N+1)/2. Additional symmetries of manifold can reduce the number
of dimensions of the ambient space required for embedding. For spherically
symmetric static manifolds this number is 6. According to Birkhoff's theorem,
the only vacuum solution of Einstein's equations with such symmetry is the
Schwarzschild solution.
As Janet-Cartan theorem does not guarantee the uniqueness of embedding, there
are several embedding of the Schwarzschild metric in the 6-dimensional space.
The first of them was founded by Kasner in 1921, but the ambient space of this
embedding has two time-like directions, and so this embedding is not very interesting
for physics. The most famous of the embeddings was offered by Fronsdal in 1959,
it is a global embedding in (1+5)-dimensional Minkowskian space. However, a
significant drawback of this embedding is that it is not asymptotically flat, i. e.
does not turn into the 4-dimensional plane whereas we go far from the gravitating
mass. None of several other well-known embeddings of the Schwarzschild metric
also has this property. Thus, there is a problem: the insertion of an infinitesimal
mass in flat space changes the asymptotic behavior of its embedding, where this
mass doesn’t change the physics.
This work presents a global asymptotically flat embedding of the Schwarzschild
solution in (1+5)-dimensional flat space, and solves the problem of the asymptotics
in embedding of gravitating mass. The next step would be a generalization of this
result to the Regge-Teitelboim approach of gravity.
References
1. Fronsdal C. // Phys. Rev. 116, 778 (1959).
211
Deal.ii library as a tool to study three-body quantum
systems
Shmeleva Yulia
[email protected]
Scientific supervisor: Dr. Yarevsky E.A., Department of
State University
Few-body quantum mechanical problem is well-known challenging problem
in quantum mechanics. Provided that interparticle interactions are known, it poses
the eigenvalue or scattering problem. Their solutions should be calculated with
high accuracy and can be compared with experiment so that physical model and
numerical approach are tested [1]. Several successful approximation techniques
have been developed for few-body problem, including the Hartree Fock method,
finite difference methods and various variational approximations. The finite element
method (FEM) has originally been used in technical applications like elastic and
fluid mechanics. The implementation of the FEM in quantum mechanics was
rather rare in spite of its advantages. However, starting since 1975 some works
applying the FEM to three-body problems have appeared and demonstrated good
results in this area.
One of the available implementations of the FEM is Deal.ii library. Deal.ii is
a powerful general purpose object oriented finite element differential equations
analysis library, that provides a wide collection of tool classes such as adaptive
meshes, a variety of finite elements, parallelization and many other routines [2]. Use
of such a frameworks will significantly simplify the process of writing the program
code and let the researcher concentrate on the physical or technical problem itself.
The aim of the present work is to explore deal.II and to evaluate its efficiency,
stability and accuracy for quantum mechanical problems.
The helium atom with zero total angular momentum has been chosen as a
benchmark of the three-body Coulomb problem. Both the exact three-dimensional
Schrodinger equation and the two-dimensional S-wave model have been
investigated. The ground state energy has been calculated and compared to the high
precision results. Convergence properties and the accuracy of the energy spectrum
have been analyzed on static and adaptive grids. The results show that Deal.ii
library can be successfully used for accurate quantum mechanical calculations
while it is not always efficient.
References
1. Elander N., Yarevsky E. // Phys. Rev. A, 56(3) (1997) 1855-1864.
2. dealii.org (A Finite Element Differential Equations Analysis Library).
212
Second order effects in the hyperfine and Zeeman
splittings in highly charged ions
Sokolov Mikhail
[email protected]
Scientific supervisor: Dr. Glazov D.A., Department of Quantum
Mechanics, Faculty of Physics, Saint-Petersburg State
University
Development of experimental techniques for cooling and trapping of individual
charged particles has lead to the measurements of the g factor of light hydrogenand lithium-like ions with a relative accuracy of 10-9 [1,2]. In turn, it motivates for
high-precision theoretical calculations [2]. In the boronlike systems, which are of
particular interest presently [3], the non-linear effects in magnetic field become
considerable. In the present work the second- and third-order effects for the ground
state 1s22s22p1/2 of the boronlike argon ion 40Ar13+ are investigated.
Possible influence of the second-order effects in the hyperfine interaction on the
observed transition energies between the fine-structure components is estimated as
well. The case of boronlike argon is considered, where high-accuracy experimental
values are available [4]. The results for various argon isotopes 33Ar, 35Ar, 37Ar and
39
Ar are presented.
References
1. Sturm S. et al., // Phys. Rev. Lett. 107, 023002 (2011).
2. Mohr P.J., Taylor B.N., and Newell D.B. // Rev. Mod. Phys. 80, 633 (2008),
and refs. therein.
3. Vogel M. and Quint W. // Phys. Rep. 490, 1 (2010).
4. Draganic I. et al. // Phys. Rev. Lett. 91, 183001 (2003).
213
Converting of images from medical format DICOM
to the standard format of bitmap images without
distortions
Sosnov Dmitry
[email protected]
Scientific supervisor: Dr. Nemnugin S.A., Faculty of Physics,
One of the most effective methods of treatment of oncologic diseases is the
hadronic therapy, which consists in bombing of the amazed site of patient's body
by a fascicle of high-energy elementary particles. However thus as a result of
treatment there is a damage of healthy tissues, which are on a movement trajectory
of fascicle. At the same time, the curve of the energy loss of particles from the
depth of penetration into the material (so-called "Bragg curve") there is a peak
("Bragg peak") corresponding to a sharp increase in the particle of given energy at
relatively low power losses on other sites of particle's path. The use of the Bragg
peak for the cancer treatment by method of hadronic therapy may significantly
decrease damage of other tissues and organs of the patient.
The main problem hindering the application of these technologies to the method
of hadronic therapy is the difficulty of determining the position of the Bragg
peak, the theoretical dependence from fascicle parameters of which could not be
established. As a consequence, the peak position depending from the density, beam
energy and biological parameters of overcome substance can be calculated only
by computer simulation of particles behavior.
For applying of computer simulation results to real medical research it is necessary
to use three-dimensional models of organs the most approached to the various options
of real human bodies. For these purposes is probably to use electronic or X-ray
tomographic results of inspections of real people. Their results are stored at medical
facilities in the industry standard of medical files DICOM 3.0 (Digital Imaging
and COmmunications in Medicine) [1]. This standard uses its own internal storage
technologies, and therefore it is necessary to transform single or series of images to
common raster graphic formats for use images of organs in modeling.
The purpose of work is preparing of automated translation of images obtained at
medical survey to the standard formats of raster representations of images without
the compression or other distortions.
In work has been developed a two-step algorithm for images converting from a
DICOM format to BMP format. For ensuring independence from platform, the application
was developed on intermediate-level language C++ [2] without using any external library
and tested on the results of computed tomographic scanning of patients.
References
1. http://medical.nema.org
2. Страуструп Б. Язык программирования C++.– М.: Бином, 2007. – 1054 с.
214
Calculation of the probability of the ionization in the
hydrogen atom under the external electric field
Sosnova Ksenia
[email protected]
University
In the present work we have dealt with hydrogen atom in the permanent electric
field. It is well known that there is probability of ionization of the electron under
these circumstances and our aim is to calculate it. Two approaches were used: the
complex scaling method and another one, resulting from the non-stationary case.
Complex scaling method is a widespread method in the atomic and molecular
physics. The complex eigenvalues (energies) and wave functions of the resonance
states were obtained with this method. The imaginary part of the energy is directly
associated with the probability of the ionization per time unit. We are going to
apply complex scaling method to the problems of the multiphoton ionization of
the hydrogenlike ions and generation of the high order harmonics.
In this work the non-stationary Schrödinger equation was solved. We cut the
parts of the wave function which are located far from the nucleus with the filterfunction. They are considered to be ionized. We obtained the time dependence of
the wave function norm (n = n0e-Гt) where Г is the probability of the ionization.
In both cases we used the generalized pseudospectral method [1] to discretize
the Hamiltonian which contains the operator of the kinetic energy, the Coulomb
interaction with the nucleus and interaction with the external electric field.
References
1. Dmitry A. Telnov, Shih-I Chu // Phys. Rev. A 76, 043412 2007.
215
Hamiltonian mechanics in spaces of constant negative
curvature
Stepanov Vasiliy
[email protected]
Scientific supervisor: Prof. Manida S.N., Department of High
Investigations of non-flat spaces are motivated by existence of non-nil term in
Einstein equation, corresponding to cosmological constant. Non-nil cosmological
constant means curved space, and at first spaces of constant curvature must be
investigated. Lagrangian and integrals of motion have been introduced for spaces
of constant curvature.
The aim of the present work is to introduce Hamiltonian mechanics in the antide Sitter space (AdS), i.e. in space of constant negative curvature, described by
radius R and velocity of light c. Impulse and Hamiltonian were deduced and 10
integrals of motion were also calculated due to Noether theorem and Lagrangian
symmetries in terms of dynamical variables.
At first all calculations have been carried out in Beltrami coordinates. In those
coordinates free particle equations of motion are linear, but free particle Hamiltonian
does not coincide with free particle energy. In order to make them match new
coordinates are required. Such coordinates are derived in the present work and
in those coordinates operation of time translation is trivial, and Lagrangian,
Hamiltonian and energy are time-idependent.
Next step is to consider the contribution of order (1/R)2 to Schrödinger's equation
for free particles in Galilei's or paraGalilei's space.
References
1. W. de Sitter // Monthly Notices of the Royal Astronomical Society, Vol. 71,
1911, p. 388-415.
2. Manida S.N. Additional Chapters of Physics. Mechanics. Saint-Petersburg:
Faculty of Physics printing establishment, 2007. - p. 57.
216
3D isotropic random walks with exponential distribution
on free paths. Application to evaporation of a droplet at
transient Knudsen numbers
Telyatnik Rodion
[email protected]
Scientific supervisor: Prof. Dr. Adzhemyan L.Ts., Department of
University
The classical problem of random walks (RW), first formulated by Pearson in
1905 [1, 2], is the question about the probability to find a random walker at certain
distance from the start point after n steps, that can occur in general at random
direction and random distance with given probability distributions (the simplest
case is the isotropic walks with constant step length λ). In most cases of arbitrary
distributions, numbers n and space dimensions solution can’t be expressed in
elementary functions [2]. For n→∞ and λ→0 Rayleigh found Gaussian asymptotic
solution for similar problem [3] that reflects in fact Central Limit Theorem about
sum of random independent identically distributed values, while Einstein obtained
[4, 5] this asymptotic solution as Green function for diffusion equation that he
derived from the recurrent chain equation of RW [6].
In this article we treat 3D isotropic RW with exponential distribution on free
paths with mean value λ and mean free time τ [7, 8]. For the centrally symmetric
system with known concentration ρ(r,t) of particles we found new concentration
ρ(r,t+τ) after one step of RW and ρ(r,t+nτ) in diffusional limit. Solution is expressed
in terms of exponential integrals that can be evaluated only computationally.
Solution was also applied to the problem of the droplet growth in surrounding vapor
as generalization to the case of transient Knudsen number, when λ is comparable
to the radius of a droplet and the mass exchange between drop and vapor can be
accounted neither in the limit of diffusive flow nor in the limit of free molecular
flow, but the mixing of these flows causes exponential Langmuir jump of vapor
concentration near the surface of a drop [9].
Obtained solutions were approved by direct simulations of RW.
References
1. Bazant M.Z. et al. // MIT lecture notes №18. 366 (2006), №18.325 (2001).
2. Hughes B.D. // Random walks and random environments, chap. 2 (1995).
3. Lord Rayleigh // Philosophical magazine, v. 10, p. 73 (1880).
4. Einstein A. // Annalen der Physik (ser. 4), v. 17, p. 549–560 (1905).
5. Aranovich G., Donohue M. // Molecular Phys., v. 105, №8, p. 1085 (2007).
6. Risken H. // The Fokker-Planck Equation, chap. 2, 4 (1989).
7. Feynman R.P. et al. // The Feynman lectures on physics, chap. 43 (1963).
8. Whitman J. // Ph.D. thesis, Johns Hopkins University, Baltimore (2010).
9. Lushnikov A. et al.// Fizika aerodispersnyh sistem, v. 37, p.7 (2001).
217
Investigation of the dependence of the number of binary
interactions and the number of participants on the class
of centrality in ultrarelativistic heavy ion collisions
Vorobyev Ivan
[email protected]
Scientific supervisor: Prof. Vechernin V.V., Department of High
The investigation is connected with the activity of the SPbSU research team,
including into the ALICE at LHC and NA61/SHINE at SPS collaborations at
CERN. The SPbSU team searches for the long-range correlations, which can be
considered as one of the signs of quark-gluon strings fusion in high energy heavy
ions collisions. In the usual quark-gluon string model [1] there is no interaction
between the strings. In this model in hadron interactions the quark-gluon strings
are formed and then in the process of their fragmentation the observable hadrons
are produced. In the case of high energy heavy ion collisions one needs to take into
account interaction between strings [2], which in turn changes their fragmentation.
As quark-gluon string is an extended object in the rapidity space, i.e. contributes by
fragmentation to wide rapidity range, one can expect appearance of the correlations
between observable quantities in distant rapidity intervals [3].
The number of strings formed in the high energy collision depends on the
number of binary interactions and the number of participants. Usually for simplicity
one supposes that the event by event fluctuations of the number of strings at fixed
impact parameter value obey the Poisson distribution [4].
In present work it was shown numerically that the fluctuations of the number
of binary interactions and the number of participants don’t obey the Poisson
distribution, which affects the fluctuations of the number of strings. Using the C++
MC simulation code of AA interactions, developed in this work, the normalized
dispersions of the numbers of wounded nucleons and binary interactions were
calculated both at fixed impact parameter and at one corresponding to some
centrality class.
References
1. Kaidalov A.B. // Phys. Lett. B 116, 459, (1982); A.B. Kaidalov, K.A. TerMartirosyan // Phys. Lett. B 117, 247, (1982); A. Capella, U. P. Sukhatme, C.-I.
Tan, and J. Tran Thanh Van // Phys. Lett. B 81, 68 (1979); Phys. Rep. 236, 225
(1994).
2. Braun M.A. and Pajares C. // Phys. Lett. B 287, 154 (1992); Nucl. Phys. B 390,
542, 549 (1993).
3. Braun M.A. and Pajares C. // Eur. Phys. J. C 16, 349 (2000).
4. Vechernin V.V., Kolevatov R.S. // Phys. of Atom.Nucl. 70 (2007) 1797.
218
QED aspects of the cosmological hydrogen
recombination theory
Zalialiutdinov Timur
[email protected]
Scientific supervisor: Dr. Labzowsky L.N., Department of
University
Theory of the cosmological hydrogen recombination became one of the most
intensively discussed fundamental physics problems in the last decade. The interest
comes from the accurate measurements of the asymmetry in the temperature and
polarization distribution of the Cosmic Microwave Background (CMB). The
launching of the Plank Surveuor which enables to perform these measurements
with accuracy 0.1% makes the situation even more intriguing.
The bound-bound one-photon transitions from the upper levels to the lower ones
did not permit the hydrogen atoms to reach their ground states: each photon released
in such transition in one atom was immediately absorbed by another atom. These
reabsorption processes did not allow the radiation to escape the interaction with the
matter. As it was first established in the two-photon 2s-1s transition presents the
main channel for the radiation escape and formation of the CMB. This transition
also led to the final hydrogen recombination. Hence, the recent properties of the
CMB are essentially defined by the two-photon processes during the cosmological
recombination epoch.
There is a difference between the decay of ns(n>2), nd states and the decay
of the 2s state. This difference is due to the presence of cascade transitions as the
dominant decay channels in the cases of ns(n>2) and nd levels. For the 2s level the
cascade transitions are absent. The cascade photons can be effectively reabsorbed
and therefore the problem of separation of the "pure" two-photon emission from
the cascade photons arises in connection with the escape probability. The separation
of the "pure" two-photon emission for the ns(n>2) and nd levels is an ambiguous
procedure. The modern astrophysical studies of the cosmological recombination
avoid using this separation. To reach the level of accuracy 0.1% for the theoretical
description of the properties of the CMB many effects should be taken into account
in the astrophysical equations describing the radiation escape process.
This very complicated construction requires a careful treatment of the basic
principles which this construction is standing upon; these principles are given
by the Quantum Electrodynamics (QED). In this work we will demonstrate that
following them one can find some additional effects, small but probably seizable
at the level 0.1% and neglected in the standard astrophysical approaches.
219
PNC effects in heavy He-like ions
Zaytsev Vladimir
[email protected]
Scientific supervisor: Prof. Shabaev V.M., Department of
University
Parity nonconservation effects (PNC) in heavy few-electron ions, which arise
as a result of weak interaction between electrons and the nucleus, can give new
possibility for tests of the Standard Model. From the theoretical side, highly charged
ions are very simple systems compared with the neutral atoms. In highly charged
ions the electron-correlation effects, being suppressed by a factor 1/Z (Z is the
nuclear charge number), can be calculated to a high accuracy in the framework of
perturbation theory.
In a number of works it was proposed to use close opposite-parity levels 21S0
and 23P0 in He-like ions at Z ~ 64 and Z ~ 90 , where the PNC effect is strongly
enhanced [1-7].
In my report I would like to speak about PNC effects on recombination of a
polarized electron with unpolarized H-like Th (Z = 90) and Gd (Z = 64) ions in
case of resonance with a doubly excited state of the He-like ion. In the resonant
approximation the amplitude of this process is equal to the amplitude of radiative
and dielectronic recombinations. We consider such intermediate doubly excited
states, where the PNC effect on the dielectronic recombination cross section should
be most pronounced due to the fact that the main channel M1 is mixed with a
stronger E1 channe due to the weak interaction.
References
1. Schäfer A. et al. // Phys. Rev. A 40, 7362 (1989).
2. Labzowsky L.N. et al. // Phys. Rev. A 63, 054105 (2001).
3. Labzowsky L. and Prozorov A. // J. Phys.: Conf. Ser. 72, 012010 (2007).
4. Maiorova A.V. et al. // J. Phys. B 42, 205002 (2009).
5. Shabaev V.M. et al. // Phys. Rev. A 81, 052102 (2010).
6. Ferro F. et al. // Phys. Rev. A 81, 062503 (2010).
7. Ferro F. et al. // Phys. Rev. A 83, 052518 (2011).
220
Calculations of the transition energies and isotope shifts
in heavy atoms with vacancies in the inner shells
Zubova Natalya
[email protected]
Scientific supervisor: Prof. Tupitsyn I.I., Department of
University
High-precision calculations of the X-ray lines and the related isotope shifts in
heavy atoms are performed. The calculations start with the Dirac-Fock method and
include Breit, electron-correlation [1] and quantum electrodynamics correlations.
The nuclear charge distribution is taken into account within the Fermi model. The
approximation in which the energy is averaged over the all atomic terms of the
nonrelativistic valence configuration is employed.
The validity of this approximation was previously demonstrated in calculations
of the binding energies, the isotope and chemical shifts of X-ray lines with large
natural widths [2]. The results of calculations are compared with other theoretical
predictions and with available experimental data.
References
1. Bratsev V.F., Dayneka G.B., Tupitsyn I.I. // Bull. Acad. Sci. USSR, Phys. Ser.
41, 173.
2. Tupitsyn I., Makarov L., and Batrakov J. // Phys. Chem. Solids 159, 809
(1998).
221
H. Biophysics
Monte Carlo simulation of behavior of two polymer
chains and of polymer chain close to surface
A. Yu. Antipina, M. A. Antyukhova, A. A. Yurchenko
[email protected], [email protected], [email protected]
Scientific supervisor: Dr. Yurchenko A.A., Department of
Molecular Biophysics, Faculty of Physics, Saint-Petersburg State
University
The experiments with DNA deposition on a silicon substrate from the watersalt solution with its further metallization are held at the Department of Molecular
Biophysics, Faculty of Physics St. Petersburg State University [1]. We decided
simulate this process. The aspect of interest is that the negatively charged DNA it
deposited on the negatively charged substrate.
We studied interaction of a single polyion with the charged homogeneous
“wall” which occupies half-space with infinite flat surface in the presence of
counterions.
The behavior of two equal uncharged polymers was investigated. Monomer–
monomer interactions within each chain and between two chains were varied in
different rations to each other. Also we studied interaction of two charged polymers
in comparison with polyelectrolyte system.
The continuous and discrete models (on a simple cubic lattice) were considered
for all systems.
The programs were implemented for the calculation of the thermodynamic
dependences of the system. Calculations were made with the Monte Carlo method
using the Wang–Landau algorithm. It allowed to obtain the energy-distribution
function which made it possible to calculate various thermal characteristics of the
systems in a wide temperature range: thermodynamic quantities (internal energy,
specific heat capacity) and structural characteristics i.e. mean-square radius of
gyration, mean-square end-to-end distance, average distance between the polyion
center of mass and the wall, average mean Z-coordinate of the ions and meansquare distance between the centers of mass of two polymers.
Effect of deposition of the polyion on the substrate with the same charge (the
so called recharge effect) was clearly observed. By lowering the temperature, the
polyion approaches (deposits) to the surface of the wall. The effect increases with
the ion charge increase.
For polymer–polymer system two regimes of compactization are observed at
low temperatures: 1) common compactization of the system with tightly interwoven
chains; 2) chain becomes compact separately and then two separate globules attract
each other “sticking” finally together with their surfaces.
References
1. Puchkova A.O., Sokolov P., Petrov Yu.V., Kasyanenko N.A. // Journal of
Nanoparticle Research, 2011, February 16, pp. 1–9.
224
Temperature behavior polarized and depolarized
components of light scattering in liquid water
Bazir Anna
[email protected]
Scientific supervisor: Dr. Rolich V.I., Department of Molecular
biophysics, Faculty of Physics, Saint-Petersburg State University
We investigate temperature dependence of Rayleigh scattering in pure water
cleared by vacuum distillation.
In the experiment standard scheme of scattering by 90 degrees is realized. We
used 40mW He-Ne laser with λ=633 nm. Chosen temperature range (25-40 ºC)
was gone towards raising the temperature and back. Every temperature point was
held not less than 4 hours.
Temperature dependences having complex nonmonotonic character were
obtained in experiment. Nonlinear dependence of polarized and depolarized
components reflects the evidence of cooperative process of rebuilding in the
internal structure.
There are a lot of different models of water. Each of these models can explain
some of these anomalies but not all. Results of our work may be a criterion for
choosing that type of model, which can be able to predict complex character of
temperature dependence.
References
1. Ralph N. Dougherty, Louis N. Howard // J. Chem. Phys. 109, 17 (1998).
2. Stephanie R. Dillon, Ralph C. Dougherty // J. Phys. Chem. A 2003, 107,
10217.
3. Stanley H.E., Buldyrev S.V. // Physica A 257 (1998) 213-232.
225
The system on the base of composite tools with
shape memory effect for manipulation of biological
microobjects in habitats
Bekhtina Maria
[email protected]
Scientific supervisor: Dr. Koledov V.V., Institution of Russian
academy of sciences, Kotel’nikov Institute of Radio Engineering
Recently the micro tweezers [1] on the basis of an alloy with shape memory effect
(SME) have been created. It has record-breaking small size. The principle of its work is
based on effect of great reversible flexural deformation in composit structures Ti2NiCu/
Pt. Today probably to create tools on the basis of materials with SME, which can do
mechanical manipulations over micro- and nana objects of different nature in the
vacuum chamber of an ionic scanning microscope [1]. The purpose of the this work
was studying of physic -mechanical properties of micro bioobjects by microtools on
the basis of alloy with SME in habitats: in water and a physical solution.
At first stage of works physic-mechanical properties of modeling bio-microobjects, bacteria E-coli and parawhooping cough antibodies have been studied
(modeling objects have been given by chair of microbiology of the Moscow Medical
Academy of a name of I.M. Setchenov) In experiments physic-mechanical properties
of biological micro objects have been studied, including durability, plasticity, the
dimensional factor. The typical size of object makes – 0,2-5 microns.
At the second stage the breadboard model of system for a manipulation biomicro-objects in habitats is developed and made, including micromanipulator
Keindiek - Fig. 1(a) with heating system - Fig. 1(b) and composit micro tweezers
with SMA - Fig. 1(c).
a
b
c
Fig. 1. The basic components of system of a manipulation biological objects
in habitats: a - micromanipulator Keindiek; b- system heating with raised dust
resistor; c – micro tweezers in a blood drop.
Characteristics of a breadboard model and result of preliminary tests are resulted
in the report.
References
1. Afonina V., Zakharov D., Lebedev G., Koledov V., Lega P., Kuchin, D., Irzhak
A., Shavrov V. // Physics Procedia 10, pp. 58-64 (2010).
226
DNA interaction with aluminum ions in a solution
Belykh Roman
[email protected]
Scientific supervisor: Prof. Kasyanenko N.A., Department of
University
The influence of aluminum ions on the conformation of biological
macromolecules is in the focus of scientific researches due to the recently found
evidence that under certain conditions this metal may induce the progression of
diseases such as Alzheimer, Parkinson and encephalopathy. It was found that these
illnesses are accompanied by the localization of aluminum in the chromatin of
infected cells, wich is the reason of the genetic instability. In this connection the
investigation of DNA interaction with aluminum ions is actual. It is known that in
a solution aluminum ion interacts with the water molecules. Therefore, DNA can
interact with different forms of aluminum ions – Al3+ Al(OH)2+, Al(OH)2+.
In this paper DNA interaction with aluminum ions in 0.005 M and 1 NaCl
was studied by the methods of Low-Gradient Viscometry, UV spectrophotometry,
Circular Dichroism (used autodihrograph Mark IV, Jobin Ivon), Atomic Force
Microscopy (NanoScope IVa, Veeco),
High molecular calf thymus DNA (Sigma), M = 11∙106 Da, NaCl, AlCl3 (pure
for analysis, Merck) were used. The acid-base balance in water solutions of AlCl3
in the presence of NaCl and DNA was studied.
It was shown that in the solutions of low ionic strength the interaction of
aluminum ions with DNA causes a decrease in the volume of molecular coil.
The change in the circular dichroism spectra of DNA during the interaction with
aluminum is also observed. This indicates the influence of binding on the secondary
structure of the macromolecule. In solutions of high ionic strength (1 M NaCl)
the volume of DNA molecules remains practically constant with increasing
concentration of AlCl3 in the solution. Thus, we conclude that the interaction takes
place by means of electrostatic forces. Since the trivalent ions Fe3+ and La3+ cause
a decrease of the molecular coil volume not only at low, but also at high NaCl
concentrations due to the shrinkage of macromolecule through the formation of
intramolecular cross-links, one can assume that the binding of aluminum ions with
DNA is carried out in other way. This result was proved with the images obtained
by the Atomic Force Microscopy.
227
Application of surface plasmon resonance for the
detection of DNA immobilization on gold surface
Fironov Alexander
[email protected]
University
Nanoplasmonics is a rapidly developing branch of science. Phenomena studied
by nanoplasmonics have found their application for wide variety of tasks, such as
creation of biosensors, therapy and visualization of tumors and much more.
Metal surface modification by DNA is the first step to in-depth investigation
of DNA interaction with various compounds, using surface plasmon resonance
(SPR) technique. In this paper DNA immobilization on gold surface using
thioglycolic acid (HSCH2COOH) and Mg2+ ions as connecting agents was studied.
For detection of DNA biding the technique based on surface plasmon resonance,
which is very sensitive to modification of the metal surface was used. In addition
to data obtained from SPR method, gold surface was studied with atomic force
microscope (AFM).
According to experimental data, the modification of gold surface with
thioglycolic acid and DNA is observed, but due to certain fluctuation of results
further investigation of mechanism of interaction is suggested. The influence of
salt and polymer concentration on the angle of total internal reflection (TIR) with
the using of Kretshman prism was regarded.
228
Investigation of the martensitic transition in magnetic
alloys with shape memory effect of Ni-Mn-In
Kalimullina Elvina
[email protected]
Scientific supervisor: Dr. Koledov V.V., Institution of Russian
academy of sciences, Kotel’nikov Institute of Radio Engineering
The problem of creating new alloys with thermoelastic martensitic transformation
magnetically and shape memory effect (SME) is of great fundamental and practical
importance. Create a new family of Heusler alloys Ni-Mn-In, sensitive to the
magnetic field in the mid-range fields of 2 T can afford to solve important tasks
management tools c SME at a constant temperature by switching on / off of the
magnetic field, for example, biotechnology, microsurgery, etc. [1].
Purpose - to study phase transitions and, in particular, the evolution of the
martensite twin structure of the alloy Ni50Mn34In16.
Ni50Mn34In16 alloy was obtained by arc melting in an argon atmosphere.
Phase transformations in the alloy were studied by differential scanning calorimetry
(DSC) and thermomagnetic analysis (TMA). Martensitic domain structure (DS) was
studied by scanning electron microscopy (SEM). On the basis of the DSC and TMA
was made a preliminary finding that the martensitic transformation - two-stage,
with characteristic temperatures: Ms1 = 325 K Mf1 = 312 K, Ms2 = 312 K, Mf2
= 300 K, As1 = 306 K, Af1 = 318 K, As2 = 318 K, Af2 = 327 K. The Curie point
merges with martensitic transition. SEM confirms the presence in the sample at
room temperature martensitic domain structure, different types. For a direct check
of two-stage transition was constructed on the basis of setting the microscope
MBS-9, which allows the camcorder to record video of the martensitic domain
structure with concomitant fixation temperature with an accuracy of 0.1 K in the
range from +10 to +100 C with an accuracy of 0.1 K.
Observing the resulting video confirmed in a sample of the martensitic transition
in the following characteristic temperatures: Ms = 327 K, Mf = 306 K. Analysis of
the video evolution of relief in the sample did not show clear signs of two-stage
martensitic transition. Therefore, further study on two-stage martensitic transition
should be carried out using X-ray diffraction and transmission electron microscopy
with a temperature resolution.
References
1. Buchelnikov V.D., Vasiliev A.N., Koledov V.V., Taskaev S.V., Khovaylo V.V.,
Shavrov V.G. // Physics-Uspekhi 49 (8) (2006) pp. 871-877.
229
The effect of magnetic fields on the contraction rate of
skeletal myotubes of different maturity
Korkosh Viacheslav
[email protected]
Scientific supervisor: Dr. Belostotskaya G.B., Cytoanalysis centre
of Sechenov Institute of Evolutionary Physiology and Biochemistry
of the Russian Academy of Sciences
Magnetic fields are one of the most important external factors affecting the living
organisms. Numerous experiments on the effects of magnetic fields on various
biological objects have revealed a large number of different magnetobiological
effects. However, the mechanisms of these effects are still poorly understood,
leaving a wide field for researches.
The aim of this work was to study the effect of alternating and static magnetic
fields on the rat skeletal muscle cells, in particular on frequency of contractions of
myotubes, developing in the primary culture. Studies have shown that static and
alternating magnetic fields can cause a variety of magnetobiological effects. It was
found that the observed effects depend on the characteristics of not only external
influence, but the culture itself, which is subjected to this influence. For example,
it was shown that a static magnetic field of range 0.3-200 μT stops spontaneous
contractions of cultivated myotubes that didn’t have enough time to form an
electromechanical coupling, which triggers muscle contraction, and has a little
effect on the contraction rate of fully differentiated myotubes of late development
stages (13-15 days). Based on this, we hypothesized that a similar dependence
should be obtained for alternating magnetic fields.
In this connection, this study investigated the effect of low-frequency alternating
magnetic fields (0.01-2 Hz) on the growing culture of rat skeletal muscle cells. In the
course of our experiments it was shown that the change of the myotube contraction
rate induced by alternating magnetic fields depends on the cell's maturity. Myotubes
of late development stages have been more resistant to magnetic effects than less
mature myotubes, and that confirms our initial assumption.
230
DNA interaction with Palladium compound
K2[PdHGluCl2] in vitro
Kozhenkov Pavel
[email protected]
University
The coordination compounds of metals from Platinum group play the important
role in antitumor therapy. Amazing results were reached with the using of
Platinum drugs, but only at treatment of certain kinds of tumours. Most widely and
successfully applied drug cisplatin generates serious side-effects (toxicity and nonspecific influence). This circumstance stimulates the synthesis of new compounds
for the selection of the non-toxic medicaments with high antitumor activity. The
chemicals on the the basis of other metals — palladium, titan, ruthenium, etc. are
tested.
The influence of Palladium complex K2[PdHGluCl2] on DNA conformation in
vitro is regarded in present work. The calculation of structure of Palladium complex
is carried out. The change in the Palladium coordination sphere due to the reaction of
aquatation is analyzed. Quantum-mechanical calculations of a molecular structure
of [PdHGluCl2] with two stages of aquatation (the replacement of chlorine atoms
by water molecules) have been carried out with software packages HyperChem
8.0 and GAMESS (FireFly 7.1g). The unlimited Hartree-Fock method and bases
SBKJC VDZ ECP for Palladium, DH for Hydrogen atoms and 6,31++G** for all
other atoms have been used.
DNA circular dichroism (CD) spectra were registered with Mark 4 (Jobin Ivon,
France) autodichrograph. The absorption spectra of components in a solution were
obtained with spectrophotometer SF-56 (Russia). Atomic Force Microscopic (AFM)
images of DNA and its complexes with Palladium compound (DNA complex - Pd)
have been received by means of microscope NanoScope 4a (Veeco) in a taping
mode on air. DNA fixation on a mica surface was carried out by the spontaneous
adsorption of DNA molecules from a solution containing magnesium ions. DNA
interaction with Palladium compound was studied in 0,005 M NaCl or 0,15 M
NaCl with the variation of DNA and Pd concentration.
It is shown, that palladium complex coordinate to DNA. The binding causes
change of DNA conformation. Complex formation is realized in solutions of low
NaCl concentration, whereas under physiological conditions (in 0,15 M NaCl)
DNA interactions with Palladium compound is not observed. The analysis of data
is carried out and the model of DNA interaction with compound under study is
offered.
231
Hydrodynamical and conformational properties
poly(ethylene glycol) modified by sterically hindered
phenols in solutions
Makaronicheva Anna, Dobrun Lyudmila
[email protected]
Scientific supervisor: Dr. Mikhailova M.E., Department of Polymer
physics, Faculty of Physics, Saint-Petersburg State University
A novel class of biologically active substances was created. These are hybrid
macromolecular antioxidants based on hydrophilic polymer with chemically grafted
sterically hindered phenols (SHP) [1, 2]. Such macromolecular systems has а some
advantages: adjustable solubility; prolonged action, enhanced stability and reduced
toxicity of bioactive substances; in addition show an enhanced antiradical activity,
compared to the low-molecular weight analogs.
In this work, the molecular characteristics of conjugates are prepared via the
chemical modification of poly(ethylene glycol) (PEG) (MM=3400, 3900, 6800 and
21600 Da) by antioxidants taken from the family SHP (Fig. 1) were studied.
t-Bu
OH
O
CH2 CH2 C O CH2 CH2 O
O
C CH2 CH2
n
t-Bu
CH3
OH
t-Bu
O
CH2 CH2 C O CH2 CH2 O
O
C CH2 CH2
n
t-Bu
OH
PEG-SHP1
t-Bu
CH3
OH
PEG-SHP2
t-Bu
Fig. 1. The chemical structure of PEG conjugates with SHP.
The effects of the molecular mass of PEG and chemical structure of SHP
on the dimensions of molecules and their aggregates are studied by using of
viscometry and light scattering methods in dilute solutions.
It was shown that PEG molecules carrying end groups of SHP form micellar
aggregates that are absent in the solution of the initial polymer. Aggregates
concentration in solutions of conjugates is less than 3 %. A hydrodynamic
dimension of aggregates and individual molecules does not depend on the
chemical structure of SHP. It was found that the presence of hydrophobic ending
groups in PEG molecules causes a sharp reduction in the lower critical solution
temperature of a solution in compare to that of the initial polymer.
References
1. Filippov S.K., Lezov A.V., Sergeeva O.Yu. et al. // European Polymer Journal,
v. 44, p. 3361, (2008).
2. Domnina N.S., Sergeeva O.Yu., Koroleva A.N. et al. //Polymer Science A, v.
52, n. 9, p. 900, (2010).
232
Molecular-mass and hydrodinamic properties of
carboxybetaine copolymers in aqueous solutions
Paristov A.O., Ivanov A.D., Lezov A.A.
[email protected]
Scientific supervisor: Dr. Polushina G.E., Department of Polymer
Polyzwitterions are macromolecules with a random mixture of oppositely
charged groups. Polyzwitterions includes both polyampholytes and polybetaines.
Polyampholytes refers to those polymers that specifically possess the charged
groups on different monomer units, while polybetaine refers to those polymers
with the anionic and cationic groups on the same monomer unit. Polyzwitterions
have found applications in various fields that include biosensors, ion exchange,
model for understanding the complex behavior of proteins.
Recently, a new statistical carboxybetaine copolymers (CPB) were synthesized.
This report deals with the study of hydrodynamic and conformational properties
of CPB formed by diallyl-N-dimethylammonium and diallyl-N-methylammonio
acetate molecules in aqueous solutions, with different ionic strength.
Fig.1. Chemical srtucrure of copolymer molecule.
Three samples of CPB containing different number of polyelectrolyte (n) and
polybetaine (m) units: CPB1 n/m=7/3; CPB2 n/m =1/1; CPB3 n/m =3/7; CPB4 n/
m=9/1 were investigated by using viscosimetry, dynamic and static light scattering
methods.
Weight-average molecular masses Mw of carboxybetaine samples were
found via static light scattering in 1 M NaCl solutions. The translation diffusion
coefficients D0 and intrinsic viscosities of CPB samples were measured in the
same solvent. Molecular mass and polymerization degree of CPB samples were
calculated. The Kuhn segment length of copolymer molecules was estimated from
experimental data by using the model of free-joining chain.
233
Interpolyelectrolyte complexes formed by water soluble
cationic dendrimer and oppositely charged sulfonated
polystyrene
Peredistov Evgenii
[email protected]
Scientific supervisor: Dr. Polushina G.E., Department of Polymer
Recently much attention is given for studying of structure and properties
of interpolyelectrolyte complexes (IPEC) formed by ionogenic dendrimers and
oppositely charged linear polyelectrolytes, and biopolymers. There are a number
of studies in which linear polyelectrolytes interacts with dendrimers containing
charged ending groups. It was found that stoichiometric and nonstoichiometric IPEC
in solution of oppositely charged polyelectrolytes and dendrimers are formed.
In present work light scattering was used as method to study the interaction
between cationic dendrimers of 3 and 4 generation number (G) with low – molecular
surfactant as well as with oppositely charged sulfonated polystyrene (PSS) with
different polymerization degree in water solution. Hydrodynamic radii of dendrimer
and PSS molecules were determined in water solutions also
CH2
CH
n
N
SO3Na
PSSNa.
(+)
CH3
Structure of the
ionogenic groups
on G3.
Dendrimer G3.
It was found that interaction of dendrimers with oppositely charged PSS leads
to formation of stoichiometric and nonstoichiometric polyelectrolyte complexes
in solution. Hydrodynamic radii of nonstoichiometric complexes were determined
for different charge to charge ratio Z-/+. It was established that phase separation
in the mixtures of G and PSS takes place for Z-/+ < 1. It was shown that hydrodynamic dimension of nonstoichiomeric complexes in solution depends on the
contour length of PSS molecules.
234
Studing of the UV radiation influence on the DNA in a
solution in the presence of caffeine
Platonov Denis
[email protected]
Scientific supervisor: Dr. Paston S.V., Department of Molecular
Biophysics, Faculty of Physics, Saint-Petersburg State
University
The absorption of UV-light by the nitrogenous bases of DNA (λmax=260 nm) can
lead to changes in the structure of the macromolecule, such as hydration (occurs
only in the single-stranded DNA) and the formation of pyrimidine adducts (stable
products of addition of pyrimidine bases to other neighbour bases, in the same
DNA strand). Maximum quantum yield observed for the reaction of thymines
dimerization [1]. These damages in the DNA structure are the major cause of
mutagenic and bactericidal action of ultraviolet radiation on a cell [2].
In the present investigation caffeine was chosen as a possible DNA protector from
UV radiation (UVB range). This choice was dictated by the fact that the maximum
of caffeine absorption spectrum is at λ=272 nm (near the maximum absorption of
the DNA nitrogenous bases). Besides caffeine weakly interacts with DNA, i.e. it is
not a mutagen. Caffeine is a biologically active substance of plant origin, widely
consumed in the world. It has a strong stimulating effect on the central nervous system
[3], affects the cell cycle and the processes of repair of DNA damage [4].
After the UV-light exposure the alterations in DNA absorption and circular
dichroism (CD) spectra are observed. The DNA absorption intensity increases
at all wave lengths and the intensities of the positive and negative bands in the
DNA CD spectrum decreases monotonously with the radiation dose growth. The
alterations observed can be caused by the partial DNA denaturation and, possibly
by the modification of nitrogenous bases.
UV-irradiation also leads to the diminution of the volume of macromolecule in a
solution. In our work it is obtained by the measurement of DNA intrinsic viscosity.
The experiment shows that in the presence of caffeine in the DNA solution under
the UV-light exposure the diminution of the DNA volume is smaller. Investigation
of the dose dependences of the relative viscosity of DNA solutions also reveals the
photoprotective action of caffeine.
References
1. Smith K.C., Hanawalt P.C.. Molecular Photobiology, Acad. Pr., New York and
London, 1969.
2. Rubin A.B. Biophysics, v.2. High School, Moscow, 1987.
3. Caffeine. PubChem public chemical database (http://pubchem.ncbi.nlm.nih.
gov/summary/summary.cgi?cid=2519#Synonyms)
4. Conney A.H., Zhou S., Lee M.-J. et.al. // Toxicol. and Appl. Pharm., v. 224, p.
209, (2007).
235
Conformational and optical properties of the
macromolecules of three-decanoate cellulose in dilute
solutions
Podsevalnikova Anna, Lebedeva Elena, Pavlov Aleksey
[email protected]
Scientific supervisor: Prof. Tsvetkov N.V., Department of polymers,
The considerable equilibrium rigidity and amphiphilic properties of aliphatic
substituted cellulose esters make them perspective for generation of LangmuirBlodgett films. Successful application of such films in micro- and a nanoelectronics,
analytical biotechnology, membrane technologies excites the further researches
of these compounds. In this work conformational, hydrodynamic and optical
characteristics of three-decanoate cellulose are investigated (side groups: - CO (CH2)11 - CH3). This work continues our investigations of cellulose esters with
aliphatic side groups of different length – cellulose acetate, cellulose butyrate,
cellulose valerate, cellulose pelargonate and cellulose myristate.
There were investigated 9 samples of three-decanoate cellulose in chloroform
and tetrachloroethane by the methods of the molecular hydrodynamics
(sedimentation, translational diffusion, intrinsic viscosity) and flow birefringence.
The samples differed by the nature of a main chain – bacterial, wood, cotton,
linter, microcrystalline. An average degree of substitution is 210. The degree of
polymerization covers the range from 140 to 1390. The estimations of equilibrium
rigidity of the chain A=280 Ǻ in chloroform and A=220 Ǻ in tetrachloroethane, and
the reduced diameter d/A=0.06 in chloroform and d/A=0.05 in tetrachloroethane
were carried out.
The optical shear coefficients of the studied samples was founded. The obtained
values are negative because of negative contribution of the long aliphatic side
chains in the anisotropy of optical polarizability of the three-decanoate cellulose
macromolecules. The initial anisotropy of polarizability of the monomer unit of
the three-decanoate cellulose is in good correlation with the corresponding values
received by us earlier for various aliphatic cellulose esters.
References
1. Tsvetkov N.V., Khripunov A.K., Astapenko E.L., Didenko S.A. // Vysokomolec.
Soedin., 1995, Ser. A. 37, №8, 1306-1313.
2. Tsvetkov N.V., Bushin S.V., Bezrukova M.A, Astapenko E.L., Ivanova V.O.,
Lebedeva E.V., Mikusheva N.G., Podsevalnikova A.N., Slavyanov V.I.,Khripunov
A.K. // J. Prikladn. Khim., V.84, №1, 156-163.
236
Electron diffraction studies of calcifying nanoparticles.
Tentative results
Prikhodko Olga, Shekhovtsova N.V., Yagushkina A.U.
[email protected]
Scientific supervisors: Dr. Vasiliev S.V., Dr. Rudy A.S., Department
of Microelectronics, Faculty of Physics, Yaroslavl State
University
The paper presents the results of studies of nanoparticles from the Vorotilovo
deep scientific borehole (VDB). The morphology and phase composition of
nanoparticles were studied by means of scanning and transmission electron
microscopy.
The object of study is pure culture of bacteria Planomicrobium sp. extracted
from gneiss VDB. While studying of bacteria Planomicrobium sp. the objects with
size from 50 to 200 nm have been detected. These objects have small spherical
shape and they are similar to colonies of bacteria. Their sizes are considerably
smaller in comparison with main types of bacteria, fungal spores or cells tissues
of multicellular organisms [1].
These "colonies" were detected in different samples before by biochemists,
microbiologists, geologists. V. Kordum [2] devoted an overview of decennial studies
dedicated to these objects. The main compound is hydroxyapatite Ca5(PO4)3OH.
This statement is based on the data from the X-ray microanalysis, which has been
carried out by hydroxyapatite as internal standard.
Calcium, phosphorus and oxygen create a big number of different compounds.
This makes the interpretation of X-ray microanalysis results varied.
We have solved this problem by mean of electron diffraction using a
transmission electron microscope Tecnai G2F20 U-TWIN. We find two compounds:
Ca2Fe(PO4)2(OH)H2O and Mg(NH4)8(P3O10)2·8H2O.
The study of object’s evolution will be continued.
References
1. Alberts B., Bray D., Lewis J., Raff M., Roberts K. Molecular Biology of the
Cell. Vol. 1 / Vlasik T.N., Korzh V.P., Maresin V.M., Arzhanova T.D., Kryukova
G., ed. by G.P. Georgiev, Y.S. Chentsova, Trans. with Eng., Moscow, Mir, 1994.
p. 1-20.
2. Kordyum V.A. et. al. Biopolymers and cells dimension in architecture
microcenosis // Biopolymer Cell., V. 25, 2009. p. 403-423.
237
Silver DNA-templated nanowires
Puchkova Anastasiya
[email protected]
University
The development of “bottom-up” approach for the creation of nanosize
structures is based on the self-assembling mechanism. The typical systems using
such mechanisms are the biological objects. Therefore the utilization of biological
macromolecules and the application of their unique features are the current trends
in nanotechnology.
New methods of DNA metallization for the creation of nanostructures on the
surface are regarded in this work. First method is based on the electrochemical
reduction of silver ions binding with DNA. The special process of DNA fixation
on n-type silicon surface assembles macromolecules into extended bundles. The
metallization of DNA provides the forming of oriented nanowires with the length
of several micrometers, consisting of Ag0 clusters with diameter from 20 to 30
nanometers. We have shown that lateral dimension of nanowires depends on AgNO3
concentration in a solution during reduction of ions on DNA. Time of exposure also
influences on the result. The using of silicon reducing properties is a key moment
in this method. This approach helps to minimize the number of chemical reagents.
It is necessary emphasize that the best result of DNA metallization was obtained
not for a single molecule but for the fibrils (or bundles) of oriented DNA chains
generated on silicon surface. So, this method allows to simplify considerably the
procedure of nanowires creation. Also the comparison of DNA metallization on
n- and p-type silicon surface demonstrates that the concentration of free electrons
plays the important role during the process of silver ions reduction to Ag0 state.
The second method of the creation of metallized structures is based on selfassembly of prefabricated silver nanoparticles on DNA fibrils fixed on n-type
silicon surface. Images of DNA molecules and fabricated nanowires have been
obtained using the Atomic Force Microscope (AFM) NanoScope IVa (Veeco)
and the Scanning Ion Helium Zeiss ORION and Electron Zeiss Supra 40 VP
Microscopes (*).
Reference
1. Puchkova A. O., Sokolov P.A., Petrov U.V., Kasyanenko N.A. // Journal of
Nanoparticle Research (2011), 13: 3633-3641
*) The images were obtained in Interdisciplinary Resource Center for
Nanotechnology SPbSU.
238
Electrooptical properties and short order in isotropic
melts of smectic comb-like polymers
Zakhryapa A.V., Shakov A.R., Fiskevich T.S.
[email protected]
Scientific supervisor: Polushin S.G., Department of Polymer
Isotropic phase of mesogens is defined by the presence of pretransitional
phenomena caused by temperature variation of short order. It is well-known that
Kerr constant K varies monotonously with temperature and this dependence is
described by the Kerr law. Recently, in the isotropic melt of methacrylic polymer
with chiral side groups we observed the phenomenon of abrupt K change interpreted
as isotropic – isotropic phase transition [1]. In other articles by methods of
calorimetry [2-4] and dielectric spectroscopy [5] was established the existence of
such transitions in the isotropic melts of low molecular LC substances. In all cases,
the transition occurred only in the chiral smectic molecular systems.
In the present work we investigated the melts of comb-like polymers of different
structure. For the first time presence of isotropic – isotopic phase transition is
detected in non-chiral smectic polymer with simple molecular structure which
has acrylic main chain and mesogenic cyanobiphenyl side groups. The obtained
experimental data were analyzed using phase – degree of polymerization diagram
[6] for a homologous series thus allowing an assumption about the nature of the
transition. In wide temperature range a complex dependence K(T) for the polymer
with chiral side groups is shown, which is apparently connected with structural
rearrangements in the isotropic melt.
The authors thank Prof. V.P. Shibaev for given samples for research. The work
was supported by RFFR, grant 09-03-00872-а.
References
1. Polushin S., Rogozin V., Beloborodov I., Rjumtsev Е., Kozlovsky М. //
Macromol. Rapid Commun. 29, 224 (2008).
2. Goodby J.W., Petrenko A., Hird M., Lewis R.A., Meier J., Jones J.C. // Chem.
Commun. 1149 (2000).
3. Dodge M.R., Vij J.K., Cowling S.J., Hall A.W., Goodby J.W. // Liq. Cryst. 32,
1045 (2005).
4. Nishiyama I., Yamamoto T., Yamamoto J., Yokoyama H., Goodby J.W. // Mol.
Cryst. Liq. Cryst. 439, 55 (2005).
5. Cowling S.J., Hall A.W., Goodby J.W. // Liq. Cryst. 32, 1483 (2005).
6. Kostromin S.G., Shibaev V.P. et al. // Vysokomolekuljarnie sojedinenija, ser.А,
38, 1566 (1996) in russian.
239
Monte Carlo study of polymer chains and stars within
lattice model
Silantyeva Irina
[email protected]
Scientific supervisor: Dr. Vorontsov-Velyaminov P.N., Department
of Molecular Biophysics, Faculty of Physics, Saint-Petersburg
State University
Entropic Sampling method within Wang-Landau algorithm [1] (one of the
Monte Carlo method versions) is used for investigation of free polymer chains
[2] and polymer stars. The semi-phantom (i.e. nonreversal) random walk on 3D
simple cubic lattice is used.
The model of a 6-arm polymer star is considered. The excluded volume effect
in the athermal case is studied as a first stage. Specific excess entropy (relative
to entropy of a phantom chain) depending on the number of monomers N in the
polymer star is obtained. Comparison with chains and rings [2, 3]. shows that the
specific excess entropy of stars tends to the same limiting value for N → ∞ as that
for chains and rings.
In the thermal case we attribute an energy ε (ε > 0 or ε < 0) to each monomer
pair occurring at closest contact in order to account for interactions of nonbonded
monomers. The distributions over the number of contacts (energy) for free chains
and stars are obtained. As an example of this dependence, the advantage of the
semi-phantom walk in comparison with the phantom one is demonstrated. The
lengths (N≤100) of the chains and of star arms (Narm≤20) are varied as parameters.
Comparison of the obtained distributions for chains and stars shows that difference
between them is noticeable though not drastic. Using Wang-Landau algorithm we
can also investigate the charged models and structure properties of models [4].
This work is supported by RFBR 11-02-00084-a.
References
1. Wang F., Landau D. P. // Phys. Rev. Lett., v. 86, p. 2050, (2001).
2. Vorontsov-Velyaminov P.N., Volkov N.A., Yurchenko A.A. // J. Phys. A, v. 37,
p. 1573-1588, (2004).
3. Volkov N.A., Yurchenko A.A., Vorontsov-Velyaminov P.N. // Macromol. Theory
Simul., v. 14, p. 491-504, (2005).
4. Vorontsov-Velyaminov P.N., Volkov N.A., Yurchenko A.A.; Lyubartsev A.P. //
Macromolecular compounds А, v. 52 № 6, p. 1–19, (2010) (In Russian).
240
Silver nanoparticles and their interaction with polymers
in a solution and on the surface
Varshavskii Mikhail
[email protected]
University
Metallic nanoparticles (NPs) are at the objects of intense study due to the
rapidly developing of new approaches including nanomaterials. Their unique
size-dependent properties make these materials attractive in many areas of high
technologies. For example biosensors based on surface plasmon resonance effect
of NPs are used for different biochemical tests.
In this report we present the results of our research of spectral properties (UV
spectroscopy) of silver NPs and their interaction with charged macromolecules
in aqueous and water-salt solutions by the methods of viscometry and Circular
Dichroism. Visualization of the obtained structures was done using Atomic Force
Microscopy (NanoScope 4a, Veeco) in tapping mode in air.
Silver NPs were synthesized by our collaborators in National Technical
University of Ukraine “Kyiv Polytechnic Institute” with the use of a new electricspark dispersion technique. For the experiments we used calf thymus DNA (Sigma)
with a molecular mass 8x106 Da, determined from the value of DNA intrinsic
viscosity in 0.15 M NaCl solution and polyallylamine 25 000 Da.
It was shown that NPs have a size about 30 nm and a cubic form. They have
a characteristic absorption band with a maximum at 400 nm corresponding to the
effect of localized surface plasmon resonance for silver NPs with 30nm diameter.
The salt concentration, HCl and NaOH influence on spectral properties of NPs.
The experiment reveals that NPs interact with positively charged polymers
(polyallylamine) as well as with negatively charged polymer (DNA). Moreover, the
presence of polymers stabilizes the solution of NPs. A series of experiments show
that NPs precipitation depends on the solution ionic strength (NaCl concentration).
The interaction of NPs with DNA in a solution at different temperatures are
regarded.
241
I. Resonance Phenomena
in Condenced Matter
Hydration of NMR and quantum-chemical methods
Altynbaev Evgeniy
[email protected]
Scientific supevisor:Dr. Donets A.V., Department of Quantum
Magnetic Phenomena, Faculty of Physics, Saint-Petersburg State
University
Оne of the most interesting problem of modern biochemistry is the hydration
and solvation properties of organic molecules in aqueous salt solutions. The study
of hydration properties of the amino-acids is carried out as intermediate organic
molecules between the acids and proteins.
The 1H NMR spectra of β-alanine (40g/l ) in heavy water D2O is presented
in Fig. 1. The ratio of integrals of spectral lines shows that two protons of NH2
group and proton of COOH exchanged with free water and formed HDO and H2O
molecules. Thus, the line of the NMR spectra, corresponding to weak magnetic
field (4.65 ppm), has a chemical shift of “free” water.
To investigate
the hydration of CH3
groups in water, the
hydration of ionized
ethanoic acid was
studied by quantumchemical calculation. To study the
interaction of amino
groups with water
molecules, glycine
was optimized with
s o l v e n t v i c i n i t y.
The amino-acid was
Fig.1. 1H NMR spectra of alanine in heavy water.
placed in the center of optimized solvent cluster, which consists of fifty water
molecules. All calculations were performed for neutral and zwitterion forms (NH2CH2-COOH and NH3-CH2-COO, in the case of glycine). The proton chemical shifts
of the β-alanine were calculated.
The results of quantum chemical calculations allow us to summarize the
hydration properties of different amino-acid molecules in aqueous solution. The
calculations of NMR spectra led to the conclusion that only neutral form of alanine
presents in the solution.
References
1. Chizhik V.I. // Molec. Phys., 1997, Vol. 90, № 4, p. 653-659.
2. Vovk M.A., Pavlov M.S., Chizhik V.I. // J. Physical Chemistry. 2010, c. 250259.
244
Main magnetic field stability research of a low-frequency MRI
installation
Karlina Nikol
[email protected]
Scientific supervisor: Tutukin K.V., Department of Quantum
University
There are the various sources of a magnetic field used in MRT-tomographs. As
a rule, in modern tomographs superconducting magnets which are characterized
by high time stability of a magnetic field, are used [1]. But such magnets are the
extremely expensive. For working out of more budgetary versions of tomographs
other sources of a magnetic field are used: constant magnets, electromagnets,
solenoids. The magnetic field of two last sources depends on following factors:
sizes of a feeding current and temperature of surrounding space. If these factors
change not controllably, so that field created by these sources, have instability in
time and if a value of a magnetic field are not controlled, received MRT images
have characteristic artifacts [2].
The purpose of the given work is the writing of the program for preliminary
research time stability of a magnetic field value.
To eliminate the given problem an engineering software Mathсad 14 is used.
Our program uses series of test images to calculate size of the basic magnetic field
average value and its disorders (dispersion).
A matrix of k-spaces (experimental results) transmits on an input of this program. As a result it is possible to see, the level of stability of given magnetic field,
in the form of numerical data and shedules.
During this work the corresponding program has been written. The program
was investigated for 3 variants of change of a field in time. Thus, results of work
can be used as preliminary check of stability of a magnetic field straight ahead of
experiment.
References
1. Hornak J.P., Ph.D. - The Basics of MRI (http://www.cis.rit.edu/htbooks/mri/)
2. The quantum radiophysics: a magnetic resonance and its appendices. Studies.
The grant. 2 edition. Under the editorship of V.I. Chizhik. – SPb.: Publishing house
S.-Peterb. University, 2009.
245
Hydrogen induced phase transitions in magnesium: ab
initio study
Klyukin Konstantin
[email protected]
Scientific supervisor: Dr. Shelyapina M.G., Department of
Quantum Magnetic Phenomena, Faculty of Physics, SaintPetersburg State University
The hydrides are used as the hydrogen storage materials. Magnesium-based
hydrides stand as the most promising candidates for hydrogen storage due to its
high hydrogen uptake (up to 7.6 w% in MgH2), large reserves and low cost. The
main disadvantages of MgH2 are high temperature of hydrogen discharge, slow
desorption kinetics and a high reactivity toward air and oxygen. Nevertheless, the
transition metals (TM) doping of Mg greatly enhances the kinetics of hydrogen
uptake and release. Numerous theoretical and experimental investigations have been
made in order to understand the mechanism of hydrogen uptake by magnesium.
But there is no clear conclusion.
Here we present the results of our theoretical study of hydrogen induced phase
transitions in magnesium. We assume that there are two pathways for Mg →
MgH2 transformation. The first one, corresponds to the direct Mg (hcp) → MgH2
(rutile) transition. But even small additions of Nb or V with bcc structure can lead
to the the second two-step hydrogenation scheme: the first step is the Mg(hcp) →
Mg(bcc) transformation, which occurs near the Mg/TM interface border [1], the
second step is that upon hydrogenation of the bcc magnesium a MgHx (bcc) →
MgH2 transformation occurs.
In this contribution we have considered several possible types of MgHx structure:
a hcp structure with hydrogen in octahedral or tetrahedral sites; a bcc structure with
hydrogen in octahedral or tetrahedral sites; a rutile structure with hydrogen vacancies. In our calculation we have found out that for low hydrogen concentrations
the hcp-MgHx structure with H in octahedral sites is the most favorable one. The
bcc-MgHx structure with hydrogen in tetrahedral sites is slightly less stable. The
phase transition from the hcp (or bcc) to rutile structure occurs at x close to 0.9.
The calculations were carried out using the package WIEN2k [2].
References
1. Klyukin K., Shelyapina M.G. Abstracts of International Symposium Nuclear
Magnetic Resonance in Condensed Matter (NMRCM), St.Peterburg, 2011, p.69.
2. Blaha P., Schwarz K. and Luitz J. Computer code WIEN2k. Vienna: University
of Technology, 2000.
246
Peculiarities of 23Na quadrupole relaxation in aqueous
solutions
Kurnikov Sergey
[email protected]
Scientific supervisor: Dr. Donets A.V., Department of Quantum
University
NMR relaxation allows the estimation of the nature of dissociation in some
aqueous electrolyte solutions based on a study of hydration properties of dissolved
components and solvent molecules in a wide range of temperatures and concentrations. The use of independent and complementary experimental and computational
methods helps to study the solution structure in more details.
The Fig. 1 shows the concentration dependence of the 23Na spin-lattice relaxation in NaNO3 aqueous solutions. The slope of the experimental curve changes
drastically at concentration m = 2,3 mol ([NaNO3]:[D2O] = 1:24). The main reason
is the disappearance of zone of free solvent in the solution. The bend at concentration m=4,6 mol ([NaNO3]: [D2O] = 1:12) indicates complete disappearance of the
second layer of the hydration shells of the ion Na+.
Fig. 1 Concentration dependence of the 23Na spin- Fig. 2 The microstructure of
lattice relaxation nuclei in NaNO3 aqueous solu- the first hydration shell of sotions at 5 оС.
dium cation.
Quantum-chemical calculations of equilibrium geometry of water clusters
formed around the sodium cation were carried out. Several structures are characterized by the most stable configurations with minimal values of the energy (Fig 2).
The calculation data compared with experimental results.
References
1. Chizhik V.I. Nuclear magnetic relaxation. St. Petersburg. Ed. SPSU, 2004.
2. Panin A., Sizova O. Nonempirical calculations of molecules. St. Petersburg.
NIIH SPSU, 2002. -230 p.
247
NMR study of spin relaxation
Nefedov Denis
[email protected]
Scientific supervisor: Prof. Charnaya E.V., Department of
Solid State Physics, Faculty of Physics, Saint-Petersburg State
University
The spin relaxation rate for the isotopes of gallium in the melt increases significantly with a decrease in gallium particle size. Besides the dominant relaxation
mechanism changes from the magnetic dipole to electric quadrupole [1].
The aim of this work was the processing of the data obtained in the study of
the relaxation times of the nuclei of isotopes of gallium (69Ga and 71Ga) in confined
geometry with the use of NMR. The samples were isolated particles of gallium
with the size about of 50 microns, thin film of gallium on an opal with the thickness about of 10 microns, gallium injected into the pores of the artificial opal
and porous glass.
The measurements were carried out using a pulsed NMR spectrometer Bruker
Avance 400 with a superconducting magnet, which creates a constant magnetic field
of 9 tesla. To measure the spin-lattice relaxation of both isotopes in the samples
the method of signal recovery of the nuclear magnetization after an inverting 180°
pulse was used.
As a result of processing the experimental data and calculations magnetic
and quadrupole contributions to the spin-lattice relaxation rate in liquid gallium
were obtained.
Reduction in the size of liquid gallium sample is followed by:
1) Increase of the rate of the quadrupole relaxation;
2) Decrease of the atomic mobility;
3) Increase of the correlation time.
References
1. Tien C., Charnaya E.V., Sedych P., Kumzerov Yu.A. // FTT, 2003, vol. 45, no.
12.
248
Factors that influence signal receiving from liquid flow
by MRI in low field
Pakhnin Sergey
[email protected]
Scientific supervisor: Dr. Tyutyukin K.V., Department of Quantum
University
Magnetic resonance imaging technique is of great importance since it allows
carrying noninvasive research of internal structures as well as highly informative
measurements of different parameters inside the object. It is especially significant
when it comes to living objects. One of frequently used on humans methods is
magnetic resonance angiography. It is used to generate images of blood flow in
vessels. Motion of liquid affects obtained signal, so that there is need in correct
interpretation of such effect.
Current research was held on scanner working in low field (7 mT, 300 kHz)
using simple gradient echo sequence (GRE). Three factors were studied: “polarization”, “outflow” and “saturation”. Polarization appears due to interaction between
spin system (of liquid) and polarization system, consisting of a permanent magnet
(its field magnitude reaches up to 0.9 T) and coil-pipe. The latter is designed to
extend time spent by spin system in strong magnetic field, thereby increasing the
macroscopic magnetization vector. Outflow is a result of a directed motion of the
excited spin system relative to the receiving coil. Saturation effect appears along
with using small values of repetition time (TR) in MRI sequence, when TR is less
than spin–lattice relaxation time (T1) and thus there's not enough time for longitudinal magnetization to recover. It was found that although saturation is the most
complex parameter, it produce less effect on signal.
As a result several curves were obtained, showing how each of these three parameters affects signal in dependence of flow rate. Also was clearly illustrated how
outflow influence mr-image by means of varying values of echo time (TE) in MRI
sequence and comparing the results with images obtained on various flow rates.
References
1. Квантовая радиофизика: магнитный резонанс и его приложения. Учеб.
Пособие. 2-е изд., перераб. Под ред. В. И. Чижика. – СПб.: Изд-во С.-Петерб.
Ун-та, 2009.
2. Galvosas P. , Callaghan P.T. // J. Magn. Reson., 181, 119-125, ( 2006).
249
β-alanine hydration shells in aqueous solution studied by
NMR relaxation method and quantum chemistry
Rabdano Sevastyan
[email protected]
Scientific supervisor: Dr. Donets A.V., Department of Quantum
University
This research work is directed to investigation of solvation properties of small
organic molecules in double solutions. Considered system consists of two components: β-alanine and D2O. Two methods were used to study this system: nuclear
magnetic relaxation and quantum chemical calculations.
Analysis of the temperature and concentration dependences of spin-lattice
relaxation rates of solvent nuclei was carried out using modified method developed by V.I. Chizhik [1]. The basic method makes it possible to determine the
hydration properties of the simple ions (Na+, Cl-, Br- etc.) in aqueous electrolyte
solutions. We used the same algorithm to study the solutions containing small
organic molecules.
The water molecules in the solution with β-alanine can be divided into two
groups: free and bonded with amino acid. Relative concentration of water in particular group determines its contribution in total deuteron relaxation rate. The bands of
concentration dependences can be interpreted by changes in microstructure of the
solution. In this work two bands were registered. The concentrations of the bends
correspond to 14 and 31 molecules of D2O per one alanine molecule.
We assume that alanine contains 14 water molecules in the first hydration shell
and 31 in the full water environment. The structure of hydration shells is not sensitive to the temperature variations in the interval 2-54 °C.
The quantum-chemical calculations of β-alanine with solvent medium were
performed. Two alanine conformations are interest: neutral and zwitterion [2]. The
optimal geometry was calculated for both forms.
Firstly we used Hartree-Fock method for the geometry optimization. To reduce
the computation time a water cluster consisting of 60 molecules was optimized. The
solvent environments were calculated for all conformations in two different ways:
1. replace the central molecules in water cluster for the alanine 2. gradual addition
of H2O molecules near the alanine. Secondly we used B3LYP DFT calculations. As
a result we have coordination numbers, lengths of hydrogen bonds and quadrupole
coupling constants. This parameters helps to understand solution structure.
References
1. Chizhik V.I. // Molec. Phys., Vol. 90, № 4, p. 653-659 (1997).
2. Dobrowolski J.C., Rode J. E., Sadlej J. // Comp. and Theor. Chem. Vol. 964,
№ 1-3 p 148-154 (2011).
250
Active-shielded biplanar gradient coil design for
magnetic resonance imaging with transverse field
symmetry
Riabchun Filipp
[email protected]
Scientific supervisor: Frolov V.V., Department of Quantum
University
Nuclear magnetic resonance (NMR) is a universal noninvasive research method
providing unique information about the internal physical and chemical structure of
the matter. The phenomenon of NMR may be described as resonance absorption of
radio-frequency electromagnetic field by nuclei with nonzero spin in presence of
constant magnetic field. The resonance frequency depends linearly of the constant
magnetic field strength with a coefficient γ called gyromagnetic ratio and unique
for each isotope. Protons (1H) have the maximum value of gyromagnetic ratio
among all the stable nuclei, that's one of the reasons they are the most commonly
used isotopes in NMR spectroscopy.
Conventional NMR gives only information about the sample as a whole. But
a lot of application problems (including but not limited to medical diagnostics)
requires localized information about different parts of the sample. It can be obtained
by the magnetic resonance imaging (MRI) technique. The common idea of all the
MRI methods is varying the constant magnetic field strength over the sample, so
that the NMR signal frequency serves as a spatial position mark. Such a varying
is technically provided by using special sets of conductors called gradient coils.
The most of MRI techniques requires rapid switching of gradient coils, which
produces eddy currents in the metal of magnet causing undesirable distortions of
the magnetic field in the sample. There are two basic ways to deal with it. The first
one is simply changing the gradient pulse shape to compensate the induced eddy
currents. But such a compensation can never be full because of difference between
field geometries produced by the gradient coil and by eddy currents. The other,
more productive idea is adding some elements to the gradient coil so that its field
becomes zero outside its boundaries. This method is called active shielding and
was described by Mansfield and Chapman [1].
This work contains an example of theoretical design of a biplanar active-shielded
gradient coil by numerical calculation via self-written Fortran 77 program.
References
1. Mansfield P. and Chapman B. // J . Phys. E: Sci. Instrum. 19, 540-5, 1986.
251
Magnetic properties of magnetite Fe3O4: a density
functional theory study
Shikhman Irina
[email protected]
Scientific supervisor:Dr. Shelyapina M.G., Department of Quantum
University
Magnetite is the earliest discovered magnet. Extensive studies of Fe3O4 have
been carried out over the past 60 years. Magnetite crystallizes in the inverse
cubic spinel structure (Fd3m) above the so-called Verwey transition temperature
(tV≈120 K). But at temperature lower than tV it takes the orthorhombic structure
(Imma) [1, 2]. Because of interesting electronic and magnetic properties as well
as potential industrial applications in magnetic multilayer devices and spintronics,
magnetite has still attracted much attention.
Theoretical studies can be very helpful to understand the nature of physical
phenomena observed in magnetite, both bulk and multilayered. However, even
for the bulk Fe3O4, the calculated properties, such as density of states, magnetic
moments, magnetic anisotropy energy etc., are rather sensible to the method of
calculation [3, 4].
The aim of the present work is to study structural and magnetic properties of
magnetite by different density functional theory methods (GGA, LSDA, LDA+U)
taking into account spin-orbital interactions. All calculations were carried out using
the Wien2k package [5]. It was found, that the most accurate and suitable one for
such a system is LDA+U. It will be applied further to study Fe/Fe3O4 multilayes.
1.
2.
3.
4.
5.
6.
References
Jeng H.-T. et al. // Phys. Rev. B, v. 65, p. 094429 (2002).
Verwey E.J.W. et al. // J. Chem. Phys., vol. 15, p. 174 (1947).
Verwey E.J.W. et al. // J. Chem. Phys., vol. 15, p. 181 (1947).
Wenzel M.J. et al. // Phys. Rev. B, vol. 75, p. 214430 (2007).
Novak P. et al. // Physica B, 312-313, p. 785 (2002).
Blaha P. et al. // Comput. Phys. Commun. 59, p. 399 (1990).
252
Spin-lattice NMR relaxation in dilute solutions of
carbosilane dendrimers in CDCl3
Shishmakova Elena, Shishkin Andrey
[email protected]
Scientific supervisor: Dr. Matveev V.V., Department of Quantum
University
In this work the method of nuclear magnetic resonance (NMR) have been used
to investigate carbosilane dendrimers of two different kinds: (a) third generation
(G3R1), containing ethyl-(s)-lactate-biphenyl terminal benzene group attached to the
dendrimer by relatively long aliphatic - (CH2)11 - spacer (AS) and (b) fourth generation (G4R2) with tsianbifenyl end groups, affiliated with the shorter - (CH2)5 - AS.
The main objective of the work was a detailed comparison of the temperature
dependence of the proton spin-lattice relaxation rate (1/T1) for different groups of
a dendrimer as well as for two similar groups of different dendrimers.
The investigated systems consist of solutions of dendrimer in deuterated
chloroform (CDCl3) with concentration of about 3% by weight. The spin-lattice
relaxation times were measured using a standard pulse sequence «inversionrecovery» (π-τ-π/2), the choice of the temperature range of the investigation (320K
÷ 225K) was in accordance with the limits between the boiling and freezing points
of deuterochloroform.
The main results are:
1. In CDCl3 dilute solutions of two dendrimers of 3rd and 4th generation in
1
H spin-lattice relaxation times (T1H) were experimentally measured for spectral
lines belonging to different functional groups of a dendrimer. It is shown that for
most of the investigated lines corresponding to various parts of the dendrimer, the
decrease in signal after the second pulse is described by a single exponent, which
allows to determine the T1H for each of the lines and to construct the temperature
dependence of the relaxation rates.
2. Analysis of the temperature dependence of the relaxation rates in the dispersion region, i.e., when ω0τ ~ 1, allows us to determine the values T1H of the correlation times for CHn-groups belonging to different parts of the dendrimer as well as
to calculate the activation energy and other parameters describing the orientational
mobility of the segments of the dendrimer in solution.
3. It is confirmed that the orientation mobility of the segments of both dendrimers, in general, is in accordance with the predictions of analytical theory and
computer simulation results.
This work was partially supported by RFBR, grant 10-03-01043.
253
Bose-Einstein condensation in nuclei
Trashchenko Igor
[email protected]
Scientific supervisor: Dr. Gridnev K.A., Department of Nuclear
Bose-Einstein condensate is a aggregate state of matter consisting of bosons
cooled to temperatures near absolute zero, and condensed in the lowest quantum
state. In this condition, quantum effects begin to appear at the macroscopic level.
Back in the thirties of last century, it was suggested to consider the nucleus, with
an even number of protons equal to the number of neutrons as a system of interacting alpha-particles. This model describes well the binding energy of the most
well-known at that moment of the nuclei, which include the whole number of
alpha particles. One of the ideas arising from this model lies in the fact that the
alpha particles can be considered as bosons, since the total spin of the nucleon
is zero. Such nuclei can be considered as a system of bosons condensed at one
energy level. The fundamental equation to describe the Bose-Einstein condensate
is the Gross-Pitaevskii equation. The main idea of this equation lies in the fact that
the wave function describes the actual distribution of condensed atoms in space.
Bose condensate has one unique feature which lies in the fact that the rotation in
it forms quantum vortexes, and the number of vortices increases with increasing
speed. Gross-Pitaevskii equation is a nonlinear differential equation, which can
be solved in the Thomas-Fermi approximation, or by using the inverse scattering
method. In the inverse scattering method of soliton solutions are possible.
References
1. Alwyn С. Scott, Chu F.Y.F., Mc Laughlin David W. The Soliton: A New Concept
In Applied Science // Proceedings of tee IEEE, vol. 61, no. 10, 1973.
2. Питаевский Л.П. // УФН, том 168, номер 8, 1998.
3. Dodd R.J. //J. Res. Natl. Inst. Stand. Technol. 101, 545 (1996).
254
A DFT study of Mg-carbon complexes – hydrogen
storage materials
Veliev Eldar
[email protected]
Magnesium hydride seems to be one of the most promising hydrogen storage
materials due to its outstanding hydrogen capacity up to 7.6 wt.% for MgH2. The
main disadvantages of MgH2 are the high hydrogen release temperature, slow
hydrogen sorption kinetics and a high reactivity of Mg toward air and oxygen.
Recent experiment have shown that the addition of carbon materials, such as
nanotubes, fullerenes or fullerene soot, improves the properties of magnesium as
a hydrogen storage material [1]. However, up to now basic physical aspects of
these phenomena are not completely understood and a comprehensive insight in
the influence of carbon atoms on metal–hydrogen bonding, that plays a major role
in the stability of MgH2, is needed in finding further modifications of magnesium
hydride with better characteristics. Theoretical researchers could provide such
insight and predict which allotropes of carbon affect better the thermodynamics
and hydrogen kinetics.
In this contribution we report on the results of our theoretical study of the
influence of fullerenes and fullerene soot on the chemical bonding in magnesium
and magnesium hydride clusters. The calculations were curried out within the
framework of the density functional method using the GAMESS package. It was
found that the role of carbon atoms is ambiguous. On the one hand, they stabilize
the MgH2 molecule. On the other hand, they break atomic bonds in metallic magnesium clusters, decreasing the cluster size. As the stability of magnesium hydride
clusters becomes lower with the cluster size decreasing, the total effect of these
two contributions reduces the stability of the system, and hence the hydrogen
release temperature.
References
1. Wu C.Z., Wang P., Yao X., Liu C., Chen D.M., Lu G.Q., Cheng H.M. // J. of
Alloys and Compounds. 2006.
255
Proton spin-lattice relaxation in hydrides of disordered
Ti1‑xVx alloys
Vyvodceva Anna, Kurenkova Elena
[email protected]
Ti1-xVx alloys are promising materials for hydrogen storage. These alloys crystallize into the bcc structure in a wide range of composition. During hydrogenation a
bcc→fcc phase transition occurs. Hydrogen storage properties of these materials are
governed by their structural and kinetic parameters. Nuclear magnetic resonance
(NMR) is a powerful tool to determine both the microstructure of hydrides (including positions of hydrogen atoms and their nearest neighboring) and hydrogen
mobility in the metal lattice [1].
Here we present the results of our proton spin-lattice relaxation study in the
Ti1‑xVx Hy hydrides with x = 0.5, 0.9, 1 and y ≈ 2. The temperature dependence of
the proton spin-lattice relaxation times T1 can provide information on hydrogen
mobility in the metallic lattice. The measurements were performed using the
home-built pulse NMR spectrometer at 20 MHz with the temperature range from
190 to 360 K. The studied samples were prepared using the Self-propagating
High‑temperature Synthesis method [2].
The magnetization recovery curves for the spin-lattice relaxation times of 1H
in all studied hydrides were described by a two-exponential decay within the all
temperature range. The temperature dependence of T1 has a complicated character
with several minima for all samples. Each minimum can be attribute to a structural
phase transition (related either to changes in the metal lattice structure or rearrangements of hydrogen atoms over interstitial sites).
References
1. Kasperovich V.S., Shelyapina M.G., Khar’kov B., Rykov I., Osipov V. // Journal
Alloys and Compounds, 509 (2011) S804-S808.
2. Aleksanyan A.G., Dolukhanyan S.K., Shekhtman V.Sh., Huot J., Ter-Galstyan
O.P., Mnatsakanyan N.L. // Journal of Alloys and Compounds, 509 (2011) S786S789.
256
Table of contents
Table of Content
Programm........................................................................................................... 3
Invited Lections.................................................................................................. 9
German-Russian Interdisciplinary Science Center (G-RISC)
Prof. Eckart Rühl, Natalia Kolanovska............................................................. 10
Topological surface states by spin-resolved photoemission
Prof. Oliver Rader.............................................................................................. 11
Atom Dynamics on Reconstructed Silicon Surfaces
Prof. Alexander A. Saranin ............................................................................... 12
Presentations St. Petersburg State University Lectures mainly for students
Prof. h.c. Dirk Uhrlandt..................................................................................... 13
Solid state NMR spectroscopy and application to study properties of nanosized
systems
Prof. Dieter Michel ........................................................................................... 14
A. Chemistry..................................................................................................... 17
Quantum-chemical investigation of 2,1-benzisoxasoles formation process
Andreeva Ksenia................................................................................................ 18
Study on polyamide/montmorillonite membranes for pervaporation of methanoltoluene mixture
Avagimova Natalia............................................................................................. 19
Dependence of rheological properties of supramolecular system based on Lcysteine and silver ions on its structure
Baranova Olga................................................................................................... 20
New associates of imino- and hydroxyimino-Pt(II and IV) complexes with 18crown-6
Bulatov E.Yu.1, Chulkova T.G.1, Gushchin P.V.1,
Haukka M.2, Kukushkin V.Yu.1 . ......................................................................... 21
Thermal decomposition of РН2ВН2•NMe3
Butlak Alina, Kazakov Igor................................................................................ 22
258
Hydrated forms of lithium and sodium perchlorate in aqueous solutions by IR
spectroscopy
Davidian Anna................................................................................................... 23
Tensimetric investigation of complex formation between alumazene and
acetonitrile
. Doinikov Dmitry............................................................................................... 24
Synthesis of potential inhibitors of Estrone Sulfatase
Drozdov Andrey.................................................................................................. 25
Unusual Rh(II)-catalyzed reactions of diazoesters with α,β-unsaturated δ-(Naryl)aminoesters: tandem N-H-insertion/intramolecular cyclization into N-aryl
pyrrolidines
Galkina Olesya................................................................................................... 26
Some experimental peculiarities of behavior of multicomponent reactive systems:
solubility and critical phenomena
Golikova Alexandra, Trofimova Maya, Toikka Maria........................................ 27
Solution – solid equilibrium in systems MX2 – H2O – S (M – Cu, Co; X – Cl, Br;
S – DMSO, DMF)
Gorbunov Artem, Tikhomirova Anastasia.......................................................... 28
Effect of copper oxidation state on the structure of complexes of copper chlorides
with morpholine
Gorbunov Artem................................................................................................. 29
Investigation of oxidation processes of iron oxide-nanoparticles using NEXAFSspectroscopy
Goroncy Christian.............................................................................................. 30
Solid-contact ion-selective electrodes with ion-to-electron transducer layer
composed of nanostructured materials
Ivanova Nataliya................................................................................................ 31
Effect of nonionic surfactants on laser-induced copper deposition process
Eugene M. Khayrullina, Sergey V.Safonov ....................................................... 32
CsNdTa2O7 ion exchange reactions in the acidic solutions
Korvinson K.V. Chislov M.V............................................................................... 33
259
Synthesis, characterization and photophysical properties of gold(I)-copper(I)
alkynyl clusters with 1,4-bis(diphenylphosphino)butane ligand
Krytchankou Ilya................................................................................................ 34
Synthesis and structure of a new series of mononuclear alkynyl-phosphine Au(I)
complexes
Kulish Kirill, Shakirova Julia............................................................................ 35
Creating microelectronic elements by laser induced deposition of high-quality
copper conductor for dielectric surfaces
Logunov Lev, Tumkin Ilya, Safonov Sergey....................................................... 36
Using of semiconductor oxide films for detection of volatile organic compounds
in gases
Lopatnikov Artem............................................................................................... 37
Synthesis diaryl ethers in the presence of iron oxide (III) as the promoting agent
Lyutkin Andrew.................................................................................................. 38
Synthesis, characterization, luminescence and non-linear optical properties of
diimine platinum(II) bisacetylide complexes
Melekhova Anna................................................................................................. 39
Novel polymers with heteroaromatic structure as promising membrane materials
Pulyalina Alexandra.......................................................................................... 40
Mechanism of formation, thermal stability and thermodynamic properties of
cation-ordered layered perovskite-type titanates NaNdTiO4 and Na2Nd2Ti3O10
Sankovich Anna, Blokhin Andrey....................................................................... 41
Digital spectrographic analysis of human biological fluids for determination of
microelements
Sergey Savinov................................................................................................... 42
Design and synthesis of 3D organometallic architectures from Au(I)polyphosphines and tert-Butylamine
Shakirova Julia.................................................................................................. 43
Modification of polylactide films by aminogroups for cells cultivation
Shalak Ksenia..................................................................................................... 44
260
Synthesis of condensed imidazole derivatives with a nodal nitrogen atom pyrido[1,2-a]benzimidazoles
Sokolov Alexandr............................................................................................... 45
Aggregation processes of gold nanoparticles and CdSe/ZnS quantum dots using
multivalent ligands
Stein Benjamin................................................................................................... 46
Application of gas chromatography to the investigation of solution – solid
equilibrium in the systems salt – S – H2O (S – DMSO, DMF, 1,4 - Dioxane)
Tikhomirova Anastasia, Gorbunov Artyom........................................................ 47
Properties hybrid macromolecular antioxidants based on hydroxyethyl starch and
sterically hindered phenols
Zavyalova Margarita......................................................................................... 48
B.Geo- and Astrophysics................................................................................. 49
The double-square root approximation for converted waves – a pragmatic
approach implementation
Abakumov Ivan, Schwarz Benjamin................................................................... 50
New exact solutions of the Grad-Shafranov equation for the 2D asymmetric
current layers
Ainov Matsak..................................................................................................... 51
Influence of IMF Bx-component on the magnetotail dynamics
Amosova Mariya................................................................................................ 52
Evolution of large-scale long-lived magnetic structures, derived from synoptic
Hα charts
Avramenko Evgeniya, Abakumov Ivan............................................................... 53
Fractal characteristics of the ULF emissions during quiet and disturbed conditions
based on the data of 210 MM stations
Bondareva Tatiana............................................................................................. 54
Investigation of plasma injections into the inner magnetosphere
Chernyaev Ivan.................................................................................................. 55
Slow fluid wave in a symmetric trilayer model
Danilovskaya Ludmila....................................................................................... 56
261
Signatures of atmospheric long-period oscillations in seismometric data
Ermolenko Svetlana........................................................................................... 57
Head waves in the full waveform inversion
Kazei Vladimir .................................................................................................. 58
The application of projection operators to the studding of atmospheric waves
Lebedkina Anastasia.......................................................................................... 59
Creating software for processing GPR data in the auto mode
Mikhalaki Nadezda............................................................................................ 60
Interacting galaxies at z~0.7
Mohamed Y.H..................................................................................................... 61
Waveform inversion of microseismic data for permeability estimation
Renat Shigapov.................................................................................................. 62
Subsolar magnetic barrier properties in dependence of interplanetary parameters
Slivka Kirill........................................................................................................ 63
A study of global electric current distributions in the geomagnetosphere, based on
spacecraft magnetometer data
Yurina Agata...................................................................................................... 64
С. Mathematics and Mechanics...................................................................... 65
Programming technology for multi-agent controlling the group of UAVs
Amelin Konstantin.............................................................................................. 66
Consensus problem in multi-agent load balancing system
Amelina Natalia................................................................................................. 67
The appearance of chaos in discrete dynamical systems
Brandt Christopher ........................................................................................... 68
Frequency estimates of oscillation period for nonlinear discrete-time systems
Fyodorov Alexey................................................................................................. 69
Decentralized adaptive synchronization of dynamical networks with white noise
disturbances
Grigoriev Grigory.............................................................................................. 70
262
Upper Hausdorff dimension bounds for invariant sets of dynamical systems on
Hilbert manifold
Ignatovich Amina............................................................................................... 71
Construction of exact solutions of differential inclusions
Kasatkina Olga.................................................................................................. 72
Existence of quadratic Lyapunov function for the systems with several nonlinear
blocks
Lipkovich Mikhail.............................................................................................. 73
Algebraic approximation of global attractors of discrete dynamical systems
Malykh Artiom................................................................................................... 74
Trajectory steering problem for an autonomouswheeled robot
Melnikov Alexander........................................................................................... 75
Solvability of some class of boundary value problems for differential-difference
equations
Neverova Daria.................................................................................................. 76
Synchronization of power systems
Pchelkina Irina................................................................................................... 77
Control of the creeping three-linked robot
Plotnikov Sergei................................................................................................. 78
Taken’s time delay embedding theorem for dynamical systems on infinitedimensional manifolds
Popov Sergey...................................................................................................... 79
Energy based and sampled-data control of the cart-pendulum system
Seifullaev Ruslan................................................................................................ 80
Adaptive synchronization of networks with nonlinear delayed interconnections
Selivanov Anton................................................................................................. 81
Two-phase problem arising from a microwave heating process in nonhomogeneous
material
Serkova Nadezhda.............................................................................................. 82
Lyapunov functions in upper Hausdorff dimension estimates of cocycle
attractors
Slepukhin Alexander.......................................................................................... 83
263
Dirichlet kernel and Lebesgue constants for a certain type of Hadamard matrices
Stojanoska Irena................................................................................................ 84
Synchronization of two nonlinear Lurie systems with delaybased on passification
and backstepping
Usik Egor........................................................................................................... 85
The sunflower-equation: in search of the global attractor
Vu Xuan Tuyen................................................................................................... 86
Illiquidity measure. New empirical approach
Yamshchikov Ivan............................................................................................... 87
On qualitative characteristics of rogue waves
Yudin Alexander................................................................................................. 88
Smoothness of the value function for the optimal consumption problem with the
presence of a random income flow
Zhelezov Dmitrii................................................................................................. 89
D. Solid State Physics....................................................................................... 91
Shape memory effect in microsized samples of ferromagnetic alloy Ni-Mn-Ga
Akatyeva Christina............................................................................................. 92
The isolated molecular cluster approach and study of point surface phenomena
in TiO2
Andreev Alexey................................................................................................... 93
Atomic force microscopy as a method ofсonstructional materials study
Borygina Klavdiya, Nikolaev Philipp,
Ulyanov Pavel, Senkovskiy Boris . .................................................................... 94
Influence of boundary conditions on reflection spectra of thin films
Chernyy Valeriy.................................................................................................. 95
Hybridization of f- and d-electron states in EuRh2Si2
Chikina Alla ...................................................................................................... 96
Supersonic speed in the disperse environments
Dejnega Marina................................................................................................. 97
XPS study of kinetics of graphene hydrogenation
Fedorov Alexander............................................................................................. 98
264
The investigation of routes of the reaction NO + CO + hν → ½ N2 + CO2 on TiO2
(Hombifine N) under visible irradiation
Glazkova Nadezda, Nikitin Konstantin.............................................................. 99
Synthesis of Co-based Heusler compound on a single-crystalline silicon
Grebenyuk Georgy, Popov Konstantin............................................................. 100
Relaxation of the magnetization near Curie point in gadolinium
Kamantsev Alexander...................................................................................... 101
Model distribution of oscillator strength for X-ray transitions near and far from
the edge
Kan Yelena, Krivosenko Yury........................................................................... 102
The absorption spectra of reduced TiO2 nanocluster:TDDFT study
Khaustov Sergei............................................................................................... 103
Monte-Carlo simulation of small molecules photo adsorption on wide band gap
solids
Khramtsou Yauheni.......................................................................................... 104
Spin-orbit splitting of surface alloy Bi/Ag on Mo(100)
Klimovskikh Ilya............................................................................................... 105
Admittance spectroscopy of near-surface quantum-dimensional semiconductor
structures
Kolevatov Ilya.................................................................................................. 106
X-ray spectroscopy investigation of thin films Al2O3 synthesized on porous SiO2
by ALD
Konashuk Alecsei............................................................................................. 107
Inner-shell photoemission from caged molecules СО@C60, N2@C60
Kondratyev Sergey........................................................................................... 108
Recoil effect as a probe of interaction between a monolayer matter andunderlying
substrate
Krivosenko Yury............................................................................................... 109
Investigation of thin Ni films on Ge substrate
Kungurtsev Eugene, Rogushkin Kirill.............................................................. 110
Origin of dislocation-related luminescence
Loshachenko Anton...........................................................................................111
265
Study of structure of nanostructured Ni-Ti alloy with shape memory effect for
medical application and its application in modern dentistry
Mazaev Pavel, Petrov Alexey, Kalashnikov Vladimir,
Gizatullin Ramil, Koledov Victor..................................................................... 112
Luminescence in InGaAs/GaAs quantum wells
Morozova Polina.............................................................................................. 113
Single crystal W-probe for STM: formation, structure and physico-chemical
characteristics
Nesterova Мaria.............................................................................................. 114
The investigation of interaction of N2O and CO on VIS irradiated TiO2 (Hombifine
N) surface
Nikitin Konstantin, Glazkova Nadezda ........................................................... 115
Study of the thermomechanical properties of nanostructured Ni-Ti alloy with
shape memory effect for medical application
Petrov Alexey, Mazaev Pavel, Kalashnikov Vladimir,
Gizatulin Ramil, Koledov Victor...................................................................... 116
The velocity and absorption coefficient of ultrasound waves in suspensions of
starch
Polukhina Anastasia........................................................................................ 117
Intercalation of Al as a method of formation of quasifreestanding graphene and
modification of electronic structure in the required direction
Popova Anna.................................................................................................... 118
Conductance calculation of quantum network elementary units
Prokhorov Yury................................................................................................ 119
Bragg reflection of light from 1D photonic crystals and dynamical diffraction
theory
Romanenko Konstantin.................................................................................... 120
Anomalous shift of Bragg reflection peak in 3D photonic crystals
Rukhlov Nikita.................................................................................................. 121
The overview of ultrasonic studies of the melting-freezing phase transitions for
substances in porous matrices
Shaforostov Eugene.......................................................................................... 122
266
An electron irradiation of short-term powerful beams effect on surface morphology
of the materials LiF, Al
Soskin Aleksey.................................................................................................. 123
Ferroelastic phase transition in LiCsSO4/MCM-41 nanocomposite
Stolbova Alevtina............................................................................................. 124
Photoinduced adsorboluminescence in Mn:Zn2SiO4 phosphor
Timoshenko Artem............................................................................................ 125
The “closed-channel” property of extended current S-matrix of junction
Tsurikov Davyd................................................................................................ 126
Calculation of sound speed in artificial opal
Andrey Uskov................................................................................................... 127
Modification of the electronic structure of graphene caused by intercalation of
aluminium
Yachmenev Mikchail........................................................................................ 128
Modification of induced spin-orbit splitting of π - states of graphene in case of
combined intercalation of Bi and noble metals
Zhizhin Evgeny . .............................................................................................. 129
E. Applied Physics.......................................................................................... 131
Usage pocket COMSOL for the numerical nonstationary nonlocal plasma
modeling
Burkova Zoya................................................................................................... 132
Factorization of charge formfactors for clusterized light nuclei in reactions e+16O
and e+12C
Danilenko Valeria............................................................................................ 133
Modeling of microdischarges in air at atmospheric pressure with Comsol
Multiphysics software
Demidov Evgeny.............................................................................................. 134
Polarized static Fourier - spectrometer static fourier-spectrometer
Gorbyk Sergiy.................................................................................................. 135
Calibration and normalization problems in X-ray diffractometry for aluminum
industry
Gruzdev Mikhail ............................................................................................. 136
267
Local dynamics of director reorientation liquid crystal in 90° twist cell
Krainukov Evgeniy........................................................................................... 137
Evolution of highly oriented pyrographite surface morphology induced by a
focused electron beam
Manukhova Alisa............................................................................................. 138
Study of interaction forces between constant magnet and high-temperature
superconductor
Marek Veronika................................................................................................ 139
Usage of stereoscopic 3d-visualization technologies
Marek Veronika................................................................................................ 140
Development of a dielectric barrier discharge ion source for ion mobility
spectrometry
Pechatnikov Pavel............................................................................................ 141
Application of the methods of information theory by the example of the
measurement of kinematic quantities
Peganov Sergey................................................................................................ 142
Evaluation of the influence of readout cables in the CBM silicon tracking system
Prokofyev Nikita............................................................................................... 143
Application of graph theory to modeling of the complex hydraulic systems
Strizhenko Olga................................................................................................ 144
F. Optics and Spectroscopy........................................................................... 145
A modern implementation of Rozhdestvenski interferometer
Agishev1 N.A., Medvedeva2 T.A., Ryabchikov1 E.L.......................................... 146
Self-organization processes in cysteine – silver solutions and hydrogels
Andrianova Yana.............................................................................................. 147
Effect of polarity on the discharge with an electrolytic anode and face-type, air
yalf-space directed cathode (gatchina’s discharge) and its afterglow
Astafiev Aleksandr............................................................................................ 148
Measurement of two-photon absorption cross-section by method of comparison
with reference samples
Belskiy Denis, Belskaya Natalia...................................................................... 149
268
Study of Rb vapor fluorescence by two-photon excitation
Bondarchik Yulia.............................................................................................. 150
The research of optical spectra of oil fractions in IR-area
Chernova Ekaterina......................................................................................... 151
Exotic behavior of Penning ionization of two ultracold Rydberg atoms
Efimov Dmitry.................................................................................................. 152
Determination of composite complexes concentration using the data of Raman
spectra matrix of binary liquid mixtures
Ilchenko Aleksey, Kutsyk Andrey, Obukhovsky Vyacheslav, Nikonova Viktoria,
Lemeshko Vasiliy.............................................................................................. 153
The study of hydrogen bond cooperativity in complexes that simulate proton
transfer in serine protease fragment by infrared and ultraviolet spectroscopy
Klykov Alexander............................................................................................. 154
Efficient phosphors based on nanocrystalline powders doped with europium
Kolesnikov Ilya................................................................................................. 155
Resonance grating based on InGaAs/GaAs quantum well
Kozhaev Mikhail, Kapitonov Yury................................................................... 156
Measurements of the free-carriers relaxation time in the InGaAs quantum wells
Krjukov Anton.................................................................................................. 157
Energy transfer in the doped aromaticnitrogen-containing polycrystals
Nosova Darya.................................................................................................. 158
Luminescence of solutions of mefenamic acid
Nosova Darya.................................................................................................. 159
Asymmetry of saturated absorption resonances
Okhinchenko Ivan, Shapochkin Pavel.............................................................. 160
Plasma-chemical processes in N2-CH4 discharge plasmas
Pechenkina Olga.............................................................................................. 161
Proton positions in strong hydrogen bonds studied by H/D isotope effects in NMR
spectra
S.A. Pylaeva1, T.A. Krinitskaya1, B. Koeppe2,
P.M. Tolstoy1,2 .................................................................................................. 162
269
Coherent excitation of neon in the extreme ultraviolet regime
C. Raschpichler, J. Plenge, A. Wirsing, B. Wassermann, E. Ruehl.................. 163
Characterization of structures with quantum wells using the resonant exitonic
reflectance spectroscopy
Ryzhov Ivan...................................................................................................... 164
On the determination of three-photon ionization probability of Xe atom
Sanina Elizaveta............................................................................................... 165
Study of the vibrational spectrum of solid and liquid sulfur
Savel'eva Svetlana............................................................................................ 166
Vibrational spectra of germane GeH4 and silane SiH4 in low-temperature
matrices
Savvateev Konstantin....................................................................................... 167
Efficient generation of quasi-monochromatic X-rays using superpower
femtosecond laser pulses
Sedov Maxim, Goryaev Andrey, Shebarshin Pavel.......................................... 168
Fresnel Lens
Semenov Semen................................................................................................ 169
Laboratory prototype of holographic display, optimized for humane eye
observation
Sevryugin Alexander, Pasechnik Irina............................................................. 170
Wide aperture source of spatially coherent white light
Shalymov Egor, Gorelaya Alina, L’vova Alyona, Sedov Maxim...................... 171
Hybrid genetic algorithm for the spectroscopic data processing
Shaymukhametova Elvira................................................................................. 172
Effect of the imaginary part of nondiagonal elements of the relaxation matrix on
the rotovibrational band shape
Sinyakova Tatyana........................................................................................... 173
Thermo optical study of liquid-crystal polymer
Sitnikova Vera ................................................................................................. 174
Observation of the fine structure for rovibronic spectral lines in visible part of
emission spectra of D2
Umrikhin Ivan, Zhukov Alexey......................................................................... 175
270
Determination of the isotopic composition and thicknesses of thin targets
Vorotynskiy Andrey........................................................................................... 176
FTIR study of hydrogen bonded complexes of phosphinic acid with different
acceptors in the gas phase
Zakirov Ildar.................................................................................................... 177
G. Theoretical, Mathematical and Computational Physics....................... 179
Conservation laws and energy-momentum tensor in Lorentz-Fock space
Angsachon Tosaporn........................................................................................ 180
Mathematical modeling of the Casimireffect based on the discrete sources
method
Baryshev Alexandr........................................................................................... 181
Renormalization – group functions as convergent integrals
Batalov Lev...................................................................................................... 182
Integration of UrQMD event generator with package ROOT
Bondarenko Artem........................................................................................... 183
Ionization probabilities in low-energy heavy-ion collisions
Bondarev Andrey.............................................................................................. 184
The influence of molecular clusterisation on vibration spectrum of methanol
Borzda Tania.................................................................................................... 185
Surface states in half-infinite superlattice with rough boundary
Bylev Alexander............................................................................................... 186
Modelling of thermal-hydraulic processes in complex domains by conservative
immersed boundary method
Chepilko Stepan............................................................................................... 187
Development of functional integration techniques for drift-diffusion processes on
Riemannian manifolds
Chepilko Stepan............................................................................................... 188
Calculation of one-particle green's function in extended koopmans'
approximation
Demidov Iurii................................................................................................... 189
271
Multifractal generalization of the detrending moving average approach to time
series analysis
Ganin Denis..................................................................................................... 190
Determination of the type of hydrogen bonded formations which occur in
higher alcohols by means of vibrational spectroscopy and quantum-chemical
calculations
Golub Pavlo..................................................................................................... 191
Optimization of high energy physics simulator MPDRoot
Kashirin Dmitrii, Blinnikov Oleg..................................................................... 192
Propagation of photons and massive vector mesons between a parity breaking
medium and vacuum
Kolevatov Sergey.............................................................................................. 193
Diffraction approach to the quantum three-body scattering problem
Koptelov Yaroslav, Timofeeva Daria................................................................ 194
Analytical solution of two-dimensional Scarf II model by means of SUSY
methods
Krupitskaya Ekaterina..................................................................................... 195
Calculations of charge-transfer in U92+ - U91+ collision usingthe finite basis set of
Hermitian B-splines
Maltsev Ilya...................................................................................................... 196
Effects of turbulent mixing on critical behaviour: renormalization group analysis
of the ATP model
Malyshev Aleksei.............................................................................................. 197
Inertial-range behaviour of a passive scalar field in a random shear flow:
renormalization group analysis of a simple model
Malyshev Aleksei.............................................................................................. 198
Investigation of the mean field and excluded-volume models in the kinetics of
nucleation stage
Markov Maksim............................................................................................... 199
Effects of Stefan’s flow and concentration-dependent diffusivity in binary
condensation
Martyukova Darya........................................................................................... 200
272
Application of 2D-correlation spectroscopy method for interpretation of spectra
and enhancing the spectral resolution
Maximova Ekaterina, Derzhavets Lev............................................................. 201
The effective 8-spinors model of elementary particles
Molotkov Viacheslav........................................................................................ 202
Magnetization reversal in spring magnets
Moskalenko Mary............................................................................................. 203
A matrix approach for the dyadic Green's function in multilayered elastic media.
Nikitina Margarita........................................................................................... 204
Detectable effects in classical supergravity
Niyazov Ramil.................................................................................................. 205
Calculation of characteristics of critical behavior in logarithmic dimensions
Pismenskiy Artem............................................................................................. 206
Numerical solution of the non-stationary Dirac equation for systems with axial
symmetry
Rozenbaum Efim............................................................................................... 207
Investigation of Bragg peaks in heterogeneous biological models
Ruban Olga...................................................................................................... 208
B-meson decay constant within QCD sum rules with Modified correlator
Rusov Aleksey................................................................................................... 209
Triple differential cross sections for (e, 2e) ionization of molecular targets
Shevyakina Natalya.......................................................................................... 210
New embedding of the Schwarzschild black hole metric
Sheykin Anton................................................................................................... 211
Deal.ii library as a tool to study three-body quantum systems
Shmeleva Yulia................................................................................................. 212
Second order effects in the hyperfine and Zeeman splittings in highly charged
ions
Sokolov Mikhail............................................................................................... 213
273
Converting of images from medical format DICOM to the standard format of
bitmap images without distortions
Sosnov Dmitry.................................................................................................. 214
Calculation of the probability of the ionization in the hydrogen atom under the
external electric field
Sosnova Ksenia................................................................................................ 215
Hamiltonian mechanics in spaces of constant negative curvature
Stepanov Vasiliy............................................................................................... 216
3D isotropic random walks with exponential distribution on free paths. Application
to evaporation of a droplet at transient Knudsen numbers
Telyatnik Rodion.............................................................................................. 217
Investigation of the dependence of the number of binary interactions and the
number of participants on the class of centrality in ultrarelativistic heavy ion
collisions
Vorobyev Ivan................................................................................................... 218
QED aspects of the cosmological hydrogen recombination theory
Zalialiutdinov Timur........................................................................................ 219
PNC effects in heavy He-like ions
Zaytsev Vladimir.............................................................................................. 220
Calculations of the transition energies and isotope shifts in heavy atoms with
vacancies in the inner shells
Zubova Natalya................................................................................................ 221
H. Biophysics.................................................................................................. 223
Monte Carlo simulation of behavior of two polymer chains and of polymer chain
close to surface
A. Yu. Antipina, M. A. Antyukhova, A. A. Yurchenko........................................ 224
Temperature behavior polarized and depolarized components of light scattering
in liquid water
Bazir Anna....................................................................................................... 225
The system on the base of composite tools with shape memory effect for
manipulation of biological microobjects in habitats
Bekhtina Maria................................................................................................ 226
274
DNA interaction with aluminum ions in a solution
Belykh Roman.................................................................................................. 227
Application of surface plasmon resonance for the detection of DNA immobilization
on gold surface
Fironov Alexander........................................................................................... 228
Investigation of the martensitic transition in magnetic alloys with shape memory
effect of Ni-Mn-In
Kalimullina Elvina........................................................................................... 229
The effect of magnetic fields on the contraction rate of skeletal myotubes of
different maturity
Korkosh Viacheslav.......................................................................................... 230
DNA interaction with Palladium compound K2[PdHGluCl2] in vitro
Kozhenkov Pavel.............................................................................................. 231
Hydrodynamical and conformational properties poly(ethylene glycol) modified
by sterically hindered phenols in solutions
Makaronicheva Anna, Dobrun Lyudmila . ...................................................... 232
Molecular-mass and hydrodinamic properties of carboxybetaine copolymers in
aqueous solutions
Paristov A.O., Ivanov A.D., Lezov A.A............................................................ 233
Interpolyelectrolyte complexes formed by water soluble cationic dendrimer and
oppositely charged sulfonated polystyrene
Peredistov Evgenii........................................................................................... 234
Studing of the UV radiation influence on the DNA in a solution in the presence
of caffeine
Platonov Denis................................................................................................. 235
Conformational and optical properties of the macromolecules of three-decanoate
cellulose in dilute solutions
Podsevalnikova Anna, Lebedeva Elena, Pavlov Aleksey................................. 236
Electron diffraction studies of calcifying nanoparticles. Tentative results
Prikhodko Olga, Shekhovtsova N.V., Yagushkina A.U..................................... 237
Silver DNA-templated nanowires
Puchkova Anastasiya....................................................................................... 238
275
Electrooptical properties and short order in isotropic melts of smectic comb-like
polymers
Zakhryapa A.V., Shakov A.R., Fiskevich T.S.................................................... 239
Monte Carlo study of polymer chains and stars within lattice model
Silantyeva Irina................................................................................................ 240
Silver nanoparticles and their interaction with polymers in a solution and on the
surface
Varshavskii Mikhail.......................................................................................... 241
I. Resonance Phenomena in Condenced Matter......................................... 243
Hydration of NMR and quantum-chemical methods
Altynbaev Evgeniy............................................................................................ 244
Main magnetic field stability research of a low-frequency MRI installation
Karlina Nikol................................................................................................... 245
Hydrogen induced phase transitions in magnesium: ab initio study
Klyukin Konstantin.......................................................................................... 246
Peculiarities of 23Na quadrupole relaxation in aqueous solutions
Kurnikov Sergey............................................................................................... 247
NMR study of spin relaxation
Nefedov Denis.................................................................................................. 248
Factors that influence signal receiving from liquid flow by MRI in low field
Pakhnin Sergey................................................................................................ 249
β-alanine hydration shells in aqueous solution studied by NMR relaxation method
and quantum chemistry
Rabdano Sevastyan.......................................................................................... 250
Active-shielded biplanar gradient coil design for magnetic resonance imaging
with transverse field symmetry
Riabchun Filipp............................................................................................... 251
Magnetic properties of magnetite Fe3O4: a density functional theory study
Shikhman Irina................................................................................................. 252
276
Spin-lattice NMR relaxation in dilute solutions of carbosilane dendrimers in
CDCl3
Shishmakova Elena, Shishkin Andrey.............................................................. 253
Bose-Einstein condensation in nuclei
Trashchenko Igor............................................................................................. 254
A DFT study of Mg-carbon complexes – hydrogen storage materials
Veliev Eldar...................................................................................................... 255
Proton spin-lattice relaxation in hydrides of disordered Ti1‑xVx alloys
Vyvodceva Anna, Kurenkova Elena................................................................. 256
Table of contents............................................................................................. 257
277