Book of abstracts - Donostia International Physics Center

Transcription

Palacio Miramar
27-29 AUGUST 2014, SAN SEBASTIAN
Fuerzas y Túnel 2014
Introduction
Welcome to the Fuerzas y Túnel 2014 conference (FyT2014) and to San Sebastian. This is the
9th edition of a series of conferences that began in Barcelona in 1998 with the aim to bring
together scientist who share an interest in the applications, the use, the development and the
theoretical description of technology based in scanning probes. We have assembled a superb
program with dedicated sessions to atomic force microscopy, scanning tunneling microscopy
and theory of local probes techniques covering a wide range of applications from soft matter
physics and biophysics to surface science in vacuum. We are very gratified by the number and
outstanding quality of contributions, from which we have selected more than thirty short talks.
We are pleased to be hosting three invited lectures of experts on AFM and STM.
Importantly, Prof. Arturo M. Baró retired this year and we have dedicated a session to honor
his extensive and inspiring career pioneering scanning probe techniques in Spain. Four invited
speakers will talk about Arturo´s scientific life from an informal and relaxed point of view.
Finally, the conference will be held at the Palacio Miramar at the city center of San Sebastian.
The location of this fantastic royal palace could not be better: right between "La Concha" and
"Ondarreta" beaches offering a splendid view over the bay and the city. We hope that you will
find time to explore and enjoy the city of San Sebastian and to join us in the conference dinner
at the typical basque "sidreria" with plenty to drink and to eat.
Enjoy the meeting!
With best wishes,
Fernando and Celia, the organizers
San Sebastián, August 27-29, 2014
I
Organizers
Celia Rogero
Fernando Moreno-Herrero
[email protected]
Centro de Física de Materiales (CSIC-UPV/EHU)
Materials Physics Center (MPC)
Paseo Manuel de Lardizabal 5
20018 San Sebastian, Spain
http://dipc.ehu.es/nanolab
[email protected]
Dept. Macromolecular Structures
Lab. B17-B-18
Centro Nacional de Biotecnología (CNB-CSIC)
C/ Darwin, 3. 28049, Cantoblanco, Spain
www.fernandomorenoherrero.com
Scientific Committee
Andrés Arnau (EHU/UPV)
Jaime Colchero (UM)
José Miguel García (IMM)
Julio Gómez (UAM)
Amadeo López de Parga (UAM)
Javier Méndez (ICMM)
Pedro J. de Pablo(UAM)
Rubén Pérez (UAM)
Juan José Saenz (UAM)
Agustina Asenjo (ICMM)
Jordi Fraxedas (CIN2)
Ricardo García (ICMM)
José María Gómez-Rodríguez (UAM)
José Angel Martin-Gago (ICMM)
Aitor Mugarza (ICN)
Jose Ignacio Pascual (CIC-Nanogune)
Roberto Otero (UAM)
Invited Speakers
Prof. Dr. Katharina J. Franke, Freie Universität, Berlín
http://www.physik.fu-berlin.de/einrichtungen/ag/ag-franke/
Prof. Dr Neil H. Thomson, University of Leeds, Leeds
http://www.astbury.leeds.ac.uk/people/staff/staffpage.php?StaffID=NHT
Prof. Dr. Pavel Jelinek, Czech Academy of Science, Praha
http://jelinekp.fzu.cz/
Session Tribute to Prof. Arturo M. Baró
Prof. Dr. Christoph Gerber, University of Basel, Switzerland
https://physik.unibas.ch/dept/pages/de/personnel/gerber.htm
Prof. Dr Ron Reifenberger, Purdue University, USA
http://www.physics.purdue.edu/people/faculty/rr.shtml
Prof. Dr. Arvind Raman, Purdue University, USA
https://engineering.purdue.edu/ME/People/ptProfile?id=12884
Prof. Dr. Ignacio Pascual, CIC Nanogune, Spain
http://www.nanogune.eu/en/research/nanoimaging/people/jose-ignacio-pascual/
II
Venue, and key locations map
Lectures will take place at the “Palacio Miramar” in San Sebastián, right between "La Concha"
and "Ondarreta" beaches (see map below). Conference dinner will be at "Ezeiza" Restaurant.
Delegates residence "Agud Querol", Materials Physics Center, and Donosti International
Physics Center sites can also be located in the following map.
Participant Information
Registration
The registration desk will open on Tuesday 26 August from 16:00 to 19:00 at the Residence
Agud Querol and on Wednesday 27 August from 8:00 to 9:00 and it will be located at Palacio
de Miramar.
2014 FyT SPM Image Contest
Bring your best SPM-based image to the Registration Desk on the 27th August or hand it to the
organizers to be part of this exiting competition. There will be a very generous prize sponsored
by Bihurcrystal for the best image selected by voting of all delegates.
Poster Session
Posters can be hanged from Wednesday to Friday. There will be a unique session where
delegates are requested to be presenting their posters. However, poster viewing can be done
over the entire duration of the conference.
Official Presenting time: Thrusday 28 August 2014, from 17:50-20:00.
Poster Prize
Two poster prizes will be awarded to the best posters presented at this conference by a
researcher in the early stages of their career (post graduate or first postdoctoral position).
III
Oral Communications
Oral communications will be given in the Lecture Theater. Please refer to the Scientific
Programme for timings.
A PC computer will be available for speakers bringing a USB stick with their talk. We encourage
the use of PowerPoint for their presentations. Alternatively, you may use your own laptop if
desired. If you are bringing a Mac, please remember to bring the necessary adaptors to plug
into a standard projector connection.
Speakers are requested to check their presentations with the chair of their session well in
advance the begining of their presenting session.
Speakers are requested to adjust to the time allocated for their talk of presentation. Session
Chairs have been told to be strict on times.
Facilities Information
Accommodation
Residencia Manuel Agud Querol. It is five minutes
http://www.resa.es/Residencias/Manuel-Agud-Querol
from
the
Lecture
Hall:
Further Information
Science for the General Public Event
In the context of science disemination for the general public, José Angel Martín Gago (ICMM,
CSIC) will talk about "El origen de la vida desde la nanociencia " at the Sala de Actos Kutxa
Andia (c/Andia s/n) on August, Tuesday 26th at 19:30h.
Certificates of Attendance
A Certificate of Attendance will be issue upon request. Attendees requiring a Certificate of
Attendance for the conference should contact the organizers or the conference registration
desk.
Internet access
Wireless internet access is available at the meeting space. Please go to the registration desk to
collect an access code for the wireless network.
How to get to San Sebastian, Spain
By plane:
- Bilbao airport (BIO): About 1 hour drive from San Sebastian. A direct shuttle bus running
every hour connects Bilbao airport and San Sebastian for about 17 euros. The bus time table is
available at http://www.pesa.net/.
- San Sebastian airport (EAS): 30 minutes drive from San Sebastian. Small airport with domestic
connections to Madrid and Barcelona. Iberia flies to this airport. A regular bus connect the
airport and the city (time table is available at http://www.lurraldebus.net/). A taxi connecting
the airport and the city should be around 30 euros.
IV
- Biarritz (BIQ): 40 minutes drive from San Sebastian. Air France flies to this airport, and some
low-cost airlines such as Ryanair also fly here. Bus connexion is available from the airport to
Donostia. For more information check http://www.conda.es/
By train:
The Adif train station “Estación del Norte” is in the center of San Sebastian, close to Urumea
river. It offers connections to several Spanish cities, including Madrid and Barcelona.
There is also Metro Donostialdea, http://www.euskotren.es, popullarly known as “Topo”, a
narrow-gauge train connecting Donostia with cities along the Basque Coast, from Bilbao and
Hendaye (France).
By bus:
The San Sebastian bus station has lines to cities troughout Spain. The main company traveling
here is Alsa http://www.alsa.es/.
By car:
The city is connected to the rest of Spain by the N-1 (Madrid-Irun highway), AP-8 (Bilbao-Irun
highway), and A-15 (Pamplona-San Sebastian highway).
V
Scientific Programme
Tuesday 26 August 2014
17:00-19:00
Registration
Science for the general public
Sala de Actos Kutxa Andia (c/Andia s/n)
19:30-20:30
El origen de la vida desde la nanociencia
José Angel Martín Gago (ICMM-CSIC, Madrid, Spain))
Wednesday 27 August 2014
9:00-9:15
Welcome words. The organizers
Session 1. Magnetism
Session Chair:
9:15-10:00
10:00-10:20
10:20-10:40
Agustina Asenjo (ICMM-CSIC, Spain)
Manipulation of spin states and magnetic anisotropy of individual metalorganic complexes on surfaces
Katharina J. Franke (Freie Universität Berlin, Germany)
Magnetic Coupling Of Tm And Lu Adatoms With Fe Monoatomic Islands On
W(110): Spin-polarized Tunneling Microscopy And Ab-initio Calculations
David Coffey (Universidad de Zaragoza, Spain)
Effects Of The Kondo Coupling On Magnetic Adsorbates On Surfaces
Fernando Delgado (INL-International Iberian Nanotechnology Laboratory, Braga,
Portugal)
10:40-11:00
11:00-11:20
Magnetic Force Microscopy Imaging In Liquid
Pablo Ares (Universidad Autónoma de Madrid, Spain)
State Of A Single Molecule By Local Gating On A Semiconductor Surface
Jesús Martínez-Blanco (Paul-Drude-Institut für Festkörperelektronik. Berlin,
Germany)
11:20-11:40
Vector Mapping Of The Magnetic Moment Of Individual Atoms Using Spin
Polarized STM
11:40-12:00
COFFEE BREAK
María Moro (Universidad de Zaragoza, Spain)
Session 2. Synthesis on Surfaces
Session Chair:
José Ángel Martín Gago (ICMM-CSIC, Spain)
1
12:00-12:20
On-Surface Synthesis Of BN/Graphene Hybrid Structures
Carlos Sánchez-Sánchez (Empa, Swiss Federal Laboratories for Materials
Science and Technology, Switzerland)
12:20-12:40
12:40-13:00
Charge-transfer Induced Isomerization Of DCNQI On Cu(100)
Roberto Otero (Universidad Autónoma de Madrid, Spain)
Theoretical STM Characterization Of On-surface Reactions Of
Heteroaromatics
José Ignacio Martínez (Instituto de Ciencias de Materiales de Madrid, ICMM, CSIC, Spain)
13:00-13:20
Customizing Metallocene layers on Cu(111)
Maider Ormaza (Institut de Physique et Chimie des Matériaux de Strasbourg,
France)
13:20-15:30
LUNCH
Session 3. Graphene and 2D-systems I
Session Chair:
15:30-15:50
Aitor Mugarza (ICN2, Barcelona, Spain)
Electron Scattering Of Rashba-split States In The BiAg2 Surface Alloy
Stefano Schirone (ICN2 - Institut Catala de Nanociencia i Nanotecnologia,
Barcelon, Spain)
15:50-16:10
Graphene tunable electronic tunneling transparency: A unique tool to
measure the local coupling
16:10-16:30
Graphene Etching On SiC Grains As A Path To Interstellar Polycyclic Aromatic
Hydrocarbons Formation
16:30-16:50
Observation of giant bandgap renormalization and excitonic effects in a
monolayer transition metal dichalcogenide semiconductor
16:50-17:10
17:10-17:30
Héctor González-Herrero (Universidad Autónoma de Madrid, Spain)
Pablo Merino (Centro de Astrobiología INTA-CSIC, Madrid, Spain)
Miguel Moreno (University of California at Berkeley, USA)
Electrostatic Manipulation Of Graphene On Graphite
Carmen Rubio (University of Alicante, Spain)
COFFEE BREAK
Session Tribute to Prof. Arturo M. Baró
17:30-17:35
2
Welcome words
17:35-18:05
18:05-18:35
18:35-19:05
19:05-19:35
AFM Technologies in personolized medical diagnostics
Christoph Gerber (University of Basel, Switzerland)
Looking back 30 years at Baro’s Laboratorio de Nuevas Microscopías: the
recollections of a mid-western American
Ron Reifenberger (Purdue University, USA)
Scanning the trends of Atomic Force Microscopy
Arvind Raman (Purdue University, USA)
Tunneling Microscopy: Retrospectives and perspectives
Ignacio Pascual (CIC Nanogune, Donosti-San Sebastián, Spain)
Thursday 28 August 2014
Session 4. AFM Applications in Biology
Session Chair:
9:15-10:00
10:00-10:20
10:20-10:40
10:40-11:00
Pedro J. de Pablo (Universidad Autónoma de Madrid, Spain)
Realising quantitative dynamic atomic force microscopy to probe
transactions of DNA at the single molecule level
Neil H. Thomson (University of Leeds, UK)
Imaging Of Biosystems By Dynamic Atomic Force Microscopy
Magali Phaner (Université de Lyon, France)
Fast Nanomechanical Spectroscopy of Soft Matter
Alma Eva Pérez Perrino (Instituto de Ciencias de Materiales de Madrid, Spain)
Mechanical uncoating of a virus genome: an AFM-TIRF combined experiment
Alvaro Ortega-Esteban (Universidad Autónoma de Madrid, Spain)
11:00-11:20
Mechanical Properties Of Antibodies As Measured By AFM: An Atomistic
Molecular Dynamics Study
11:20-11:40
Structural Analysis Of Individual Protein Complexes By Infrared Scattering At
An AFM Tip
11:40-12:00
COFFEE BREAK
Gilherme Vilhena (Universidad Autónoma de Madrid, Spain)
Iban Amenabar (CIC nanoGUNE, San Sebastián, Spain)
Session 5. Graphene and 2D-systems II
Session Chair:
12:00-12:20
Daniel Sánchez Portal (DIPC, San Sebastián, Spain)
Scattering properties of graphene nanostructures on Ni(111)-2
Aran García-Lekue (Donostia International Physics Center (DIPC), Spain)
3
12:20-12:40
12:40-13:00
13:00-13:20
Multidomain graphene on Rh(111)_ STM study of unusual moire patterns
Ana Martín-Recio (Universidad Autónoma de Madrid, Spain)
Mechanical properties of graphene with defects created by ion bombardment
Guillermo López-Polín (Universidad Autónoma de Madrid, Spain)
Uniaxial Strain Control of Metal Insulator Transitions in Sr2IrO4 thin films
Neus Domingo (ICN2 - Institut Catala de Nanociencia i Nanotecnologia,
Bellaterra, Spain)
13:20-15:30
LUNCH
14:30-15:30
Organizing Committee Annual Meeting
Session 6. New Developments and Related Techniques
Session Chair:
15:30-15:50
15:50-16:10
16:10-16:30
Jaime Colchero (Universidad de Murcia, Spain)
In Situ High Pressure STM Imaging Of A Fischer-Tropsch Cobalt Catalyst
Violeta Navarro (Leiden University, The Netherlands)
Nanophotoactivity Of Porphyrin Functionalized ZnO Solar Cells
Elisa Palacios-Lidón (Universidad de Murcia, Spain)
Study Of Polymer Relaxation Dynamics By Means Of AFM Based Dielectric
Spectroscopy
Alejandro Miccio (Universidad del País Vasco, San Sebastián, Spain)
16:30-16:50
COFFEE BREAK
16:50-17:10
A single-molecule approach to study dynamics of DNA helicases by applying
magnetic forces
Carolina Carrasco (Centro Nacional de Biotecnología, Madrid, Spain)
17:10-17:30
17:30-17:50
XPEEM And LEEM: State Of The Art Surface Characterization Tools At ALBA
Lucía Aballe (ALBA Syncroton Light Facility, Barcelona, Spain)
Nanoscale IR Spectroscopy, Dielectric Function Mapping And Depth Profiling
With Near-field Microscopy
Alexander Govyadinov (CIC Nanogune Consolider, San Sebastián, Spain)
17:50-20:00
20:30
4
POSTER SESSION. Sponsored by
BUS TO CONFERENCE DINNER
Friday 29 August 2014
Session 7. Combined AFM/STM I
Session
Chair:
10:15-11:00
Julio Gómez. (Universidad Autónoma de Madrid, Spain)
A step further for better understanding of molecular junctions and
highresolution SPM images
Pavel Jelinek (Institute of Physics of the AS CR, Prague, Czech Republic)
Bandgap Engineering Of Bottom-Up Synthesized Graphene Nanoribbons
11:00-11:20
Dimas de Oteyza (Centro de Física de Materiales, CSIC-UPV/EHU, San Sebastián,
11:20-11:40
General Force Reconstruction Method for Amplitude Modulation Force
Microscopy Experiment
11:40-12:00
COFFEE BREAK
Spain)
Amir Farokh (Instituto de Ciencias de Materiales de Madrid, ICMM-CSIC, Spain)
Session 8. Combined AFM/STM II
Session
Chair:
Julio Gómez. (Universidad Autónoma de Madrid, Spain)
12:00-12:20
Adsorption Geometry Of Pentacene On TiO2 Anatase Surface Resolved By
Intra-molecular Atomic Force Microscopy Imaging
12:20-12:40
Attractive Tip-sample Force Reconstruction For Dynamic Atomic Force
Microscopy In Ambient Conditions
12:40-13:00
13:00-13:20
13:20
Cesar Moreno (National Institute for Materials Science (NIMS), Tsukuba, Japan)
Albert Verdaguer (Institut Català de Nanociencia i Nanotecnologia, ICN2, Spain)
Atomic Force Microscopy In High Vacuum: Experiments On Graphitic Surfaces
Miriam Jaafar (Instituto de Ciencias de Materiales de Madrid, ICMM-CSIC, Spain))
Poster and SPM Image Contest Prizes
sponsored by
Final remarks. The organizers
5
SCIENCE FOR THE GENERAL PUBLIC
Sala de actos Kutxa Andia (c/Andia s/n)
7
El origen de la vida desde la nanociencia
José Angel Martín Gago
Instituto Ciencia de Materiales de Madrid-CSIC
Entre las preguntas más recurrentes de la humanidad está la que se refiere al origen de la vida
en nuestro Planeta. Cómo y de dónde proviene el ser humano es un misterio al que distintas
religiones y filosofías se han acercado a lo largo de la historia. Hoy día también la ciencia,
utilizando exclusivamente el método científico, se plantea responder a esta pregunta: “¿de
dónde venimos? ¿cuál es nuestro origen?”.
En esta presentación intentaremos “rebobinar” la película de la vida en la Tierra, desde
nuestro mundo actual, lleno de diversidad, hasta el universo vacío y oscuro. Antes de que se
formase nuestro planeta azul sólo había un universo repleto de luz en el que vagaban algunas
pequeñas moléculas. Era el reino de la física. Poco a poco esas moléculas se encontraron en el
espacio y comenzó a funcionar la química. Después se formaron los planetas (la geología) y con
ellos la química antes de la vida. Esa química se fue convirtiendo en bio-química y
posteriormente en biología, en vida.
Por otra parte, y curiosamente, este proceso es muy similar al que persigue la nanociencia y la
nanotecnología, áreas del conocimiento que se inspiran en la forma de actuar de la naturaleza
para construir nuevos dispositivos importantes para el bienestar. La investigación actual sobre
el origen de la vida aborda una serie de retos y dificultades. Es una investigación
interdisciplinar en la que tanto la falta de datos experimentales como de otros ejemplos
conocidos de vida fuera de la Tierra son un lastre importante. En esta presentación se
revisarán esos retos; veremos cómo las nuevas tendencias en nanotecnología y el concepto
moderno del átomo pueden combinarse para darnos algunas repuestas a este tema tan difícil.
8
ABSTRACTS. ORAL PRESENTATIONS
9
List of Oral Presentations by Title
Manipulation of spin states and magnetic anisotropy of individual metal-organic complexes on surfaces....................................... 13
Katharina J. Franke ...................................................................................................................................................................... 13
Magnetic Coupling of Tm and Lu Adatoms with Fe Monoatomic Islands on W(110): Spin-polarized Tunneling Microscopy and Abinitio Calculations............................................................................................................................................................................... 14
D. Coffey, J. L. Diez-Ferrer, D. Serrate, M. Ciria, C. de la Fuente, J. I. Arnaudas ...................................................................... 14
Effects Of The Kondo Coupling On Magnetic Adsorbates On Surfaces ........................................................................................... 15
F. Delgado, Joaquín Fernández-Rossier ..................................................................................................................................... 15
Magnetic Force Microscopy Imaging In Liquid .................................................................................................................................. 15
P. Ares, M. Jaafar, A. Gil, J. Gómez-Herrero, A. Asenjo ............................................................................................................. 15
State Of A Single Molecule By Local Gating On A Semiconductor Surface ..................................................................................... 16
Jesús Martínez-Blanco, Christophe Nacci, Kyoshi Kanisawa, Steven Erwin, Stefan Fölsch ...................................................... 16
Vector Mapping Of The Magnetic Moment Of Individual Atoms Using Spin Polarized STM ............................................................ 17
M. Moro, M. Piantek, J. I. Pascual, M. R. Ibarra, D. Serrate ........................................................................................................ 17
On-Surface Synthesis Of BN/Graphene Hybrid Structures ............................................................................................................... 18
Carlos Sanchez-Sanchez, Matthias Müller, Holger F. Bettinger, Sebastian Brüller, Klaus Müllen, Leopold Talirz, Carlo
Pignedoli, Pascal Ruffieux, Roman Fasel .................................................................................................................................... 18
Charge-transfer Induced Isomerization Of DCNQI On Cu(100) ........................................................................................................ 19
C. Urban, Y. Wang, J. Rodríguez-Fernández, M. A. Herranz, M. Alcamí, N. Martín, F. Martín, J. M. Gallego, R. Otero, R.
Miranda ........................................................................................................................................................................................ 19
Theoretical STM Characterization Of On-surface Reactions Of Heteroaromatics ............................................................................ 20
Jose Ignacio Martinez, Anna Lisa Pinardi, Gonzalo Otero-Irurueta, Maria Francisca Lopez, Javier Mendez, Jose Angel MartinGago............................................................................................................................................................................................. 20
Customizing Metallocene layers on Cu(111) ..................................................................................................................................... 21
Ormaza Maider, Bachellier Nicolas, Bocquet Marie-Laure, Lorente Nicolas, Limot Laurent ....................................................... 21
Electron Scattering Of Rashba-split States In The BiAg2 Surface Alloy ........................................................................................... 21
S. Schirone, R. Piquerel, G. Bihlmayer, E. E. Krasovskii, P. Gambardella, A. Mugarza ............................................................. 21
Graphene tunable electronic tunneling transparency: A unique tool to measure the local coupling................................................. 23
H. González-Herrero, A.J. Martínez-Galera, M.M. Ugeda, F. Craes, D. Fernández-Torre, P. Pou, R. Pérez, J.M. GómezRodríguez and I. Brihuega............................................................................................................................................................ 23
Graphene Etching On SiC Grains As A Path To Interstellar Polycyclic Aromatic Hydrocarbons Formation .................................... 24
P. Merino, M. Švec, J.I. Martinez, P. Jelinek, P. Lacovig, M. Dalmiglio, S. Lizzit, P. Soukiassian, J. Cernicharo, J.A. MartinGago............................................................................................................................................................................................. 24
Observation Of Giant Bandgap Renormalization And Excitonic Effects In A Monolayer Transition Metal Dichalcogenide
Semiconductor ................................................................................................................................................................................... 25
Miguel M. Ugeda, Aaron J. Bradley, Su-Fei Shi, Felipe H. da Jornada, Yi Zhang, Diana Y. Qiu, Sung-Kwan Mo, Zahid Hussain,
Zhi-Xun Shen, Feng Wang, Steven G. Louie, Michael F. Crommie ............................................................................................ 25
Electrostatic Manipulation Of Graphene On Graphite ....................................................................................................................... 25
C. Rubio-Verdú, J. Martínez, M.J. Caturla, G. Sáenz-Arce, D. C. Milán, C. Untiedt ................................................................... 25
AFM Technologies in personolized medical diagnostics ................................................................................................................... 26
Christoph Gerber .......................................................................................................................................................................... 26
10
Looking back 30 years at Baro’s Laboratorio de Nuevas Microscopías: the recollections of a mid-western American .................. 27
Ron Reifenberger ......................................................................................................................................................................... 27
Scanning the trends of Atomic Force Microscopy ............................................................................................................................. 27
Arvind Raman .............................................................................................................................................................................. 27
Tunneling Microscopy: Retrospectives and perspectives.............................................................................. ....................................27
Ignacio Pascual ............................................................................................................................................................................ 27
Realising quantitative dynamic atomic force microscopy to probe transactions of DNA at the single molecule level ...................... 29
Neil H Thomson ........................................................................................................................................................................... 29
Imaging Of Biosystems By Dynamic Atomic Force Microscopy ........................................................................................................ 30
Magali Phaner-Goutorbe .............................................................................................................................................................. 30
Fast Nanomechanical Spectroscopy of Soft Matter .......................................................................................................................... 30
E. T. Herruzo, A.P. Perrino , R. Garcia ........................................................................................................................................ 30
Mechanical uncoating of a virus genome: an AFM-TIRF combined experiment .............................................................................. 31
A. Ortega-Esteban, K. Bodensiek, G. Condezo, M. Suomalainen, U. Greber, C. San Martín, P. J. De Pablo, I. A. T. Schaap . 31
Mechanical Properties Of Antibodies As Measured By AFM: An Atomistic Molecular Dynamics Study .......................................... 32
J.G. Vilhena, Pedro A. Serena, Ruben Perez .............................................................................................................................. 32
Structural Analysis Of Individual Protein Complexes By Infrared Scattering At An AFM Tip............................................................ 33
Iban Amenabar, Simon Poly, Wiwat Nuansing, Elmar H. Hubrich, Alexander A. Govyadinov, Florian Huth, Roman
Krutokhvostov, Lianbing Zhang, Mato Knez, Joachim Heberle, Alexander Bittner, Rainer Hillenbrand ..................................... 33
Scattering Properties Of Graphene Nanostructures On Ni(111) ....................................................................................................... 34
A. Garcia-Lekue, T. Balashov, M. Ollé, G. Ceballos, A. Arnau, P. Gambardella, D. Sánchez-Portal, A. Mugarza ..................... 34
Multidomain graphene on Rh(111): STM study of unusual moiré patterns ....................................................................................... 35
A. Martín-Recio, A. J. Martínez-Galera, J. M. Gómez-Ródriguez ................................................................................................ 35
Mechanical Properties Of Graphene With Defects Created By Ion Bombardment ........................................................................... 36
Guillermo López-Polín, Cristina Gomez-Navarro, Vincenzo Parente, Francisco Guinea, Mikhail I. Katsnelson, Francesc PerezMurano, Julio Gomez-Herrero...................................................................................................................................................... 36
Uniaxial Strain Control of Metal Insulator Transitions in Sr2IrO4 thin films ........................................................................................ 37
L. López-Mir, X.Martí, M. Paradinas, C.Ocal, G.Catalán, N.Domingo. ........................................................................................ 37
In Situ High Pressure STM Imaging Of A Fischer-Tropsch Cobalt Catalyst ..................................................................................... 38
Violeta Navarro, M.A. van Spronsen, J.W.M. Frenken ................................................................................................................ 38
Nanophotoactivity Of Porphyrin Functionalized ZnO Solar Cells ...................................................................................................... 39
Elisa Palacios-Lidón, David F. Pickup, Eneko Azaceta, Jaime Colchero, Ramón Tena-Zaera, Celia Rogero ........................... 39
Study Of Polymer Relaxation Dynamics By Means Of AFM Based Dielectric Spectroscopy ........................................................... 40
L.A.Miccio, G.A.Schwartz, A.Alegría, J.Colmenero ..................................................................................................................... 40
A single-molecule approach to study dynamics of DNA helicases by applying magnetic forces...................................................... 41
Carolina Carrasco, Neville Gilhooly, Mark S. Dillingham, and Fernando Moreno-Herrero. ......................................................... 41
XPEEM And LEEM: State Of The Art Surface Characterization Tools At ALBA .............................................................................. 42
Lucia Aballe, Michael Foerster ..................................................................................................................................................... 42
Nanoscale IR Spectroscopy, Dielectric Function Mapping And Depth Profiling With Near-field Microscopy ................................... 43
Alexander Govyadinov, Stefan Mastel, Federico Golmar, Andrey Chuvilin, P. Scott Carney, Rainer Hillenbrand ..................... 43
11
A step further for better understanding of molecular junctions and highresolution SPM images...................................................... 45
P. Jelinek ...................................................................................................................................................................................... 45
Bandgap Engineering Of Bottom-Up Synthesized Graphene Nanoribbons...................................................................................... 45
Dimas G. de Oteyza, Yenchia Chen, Ting Cao, Chen Chen, Zahra Pedramrazi, Danny Haberer, Felix R. Fischer, Steven G.
Louie, Michael F. Crommie .......................................................................................................................................................... 45
General Force Reconstruction Method for Amplitude Modulation Force Microscopy Experiment.................................................... 46
A.F. Payam, D. Martin-Jimenez , R. Garcia ................................................................................................................................. 46
Adsorption Geometry Of Pentacene On TiO2 Anatase Surface Resolved By Intra-molecular Atomic Force Microscopy Imaging . 47
Cesar Moreno, Oleksandr Stetsovych, Milica Todorovic, Tomoko K. Shimizu, Rubén Pérez, Oscar Custance ......................... 47
Attractive Tip-sample Force Reconstruction For Dynamic Atomic Force Microscopy In Ambient Conditions .................................. 48
Albert Verdaguer, Annalisa Calo, Carlo Alberto Amadei, Matteo Chiesa, Sergio Santos ........................................................... 48
Atomic Force Microscopy In High Vacuum: Experiments On Graphitic Surfaces ............................................................................. 49
M. Jaafar, G. López Polin, D. Martínez Martín, C. Gómez Navarro, J. Gómez Herrero .............................................................. 49
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Manipulation of spin states and magnetic anisotropy of individual
metal-organic complexes on surfaces
D
Katharina J. Franke
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Fachbereich Physik, Freie Universität Berlin, Berlin, Germany
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The magnetic properties of atoms and molecules on a surface are significantly affected by
details in the atomic-scale surrounding. Manipulation of this surrounding provides the
possibility to tune the electronic and magnetic functionality of surfaces on the nanometer
scale. Here, we use scanning tunneling spectroscopy to resolve the magnetic properties of
individual paramagnetic metal-organic complexes on normal metal and superconducting
surfaces.
S
We show that the lifetime of excited spin states in the paramagnetic Fe-OctaethylporphyrinChloride (FeOEP-Cl) is orders of magnitude longer when the molecule is adsorbed on a
superconductor as compared to a normal metal substrate. We ascribe this increase in spin
relaxation time to the superconducting energy gap at the Fermi level, which prohibits efficient
pathways of energy quenching into the substrate [1]. The small spin relaxation rates allow for
pumping into higher spin states by large current densities.
The magnetic anisotropy of the individual molecules can be varied by the proximity of the STM
tip. Approaching the STM tip to the molecule leads to a deformation of the molecular ligand
field, resulting in an increase in the axial anisotropy.
Removal of the central Cl ligand changes the oxidation and spin state, respectively. The spin
excitation spectra reveal a notable axial and transverse anisotropy, which are also affected by
the distance of the STM tip.
We further manipulate the magnetic properties of individual FeOEP molecules on a gold
surface by an in-situ chemical reaction of the organic ligand. A temperature-induced step-wise
electrocyclic ring closure of the ethyl groups results in the final product FeTetrabenzoporphyrin (FeTBP). The chemical modification is accompanied by an increased
magnetic interaction with the metallic substrate as resolved by changes in the shape and width
of a Kondo resonance [2].
[1]. B. W. Heinrich, L. Braun, J. I. Pascual, K. J. Franke, Nature Physics 9, 765 (2013)
[2]. B. W. Heinrich, G. Ahmadi, V. L. Müller, L. Braun, J. I. Pascual, K. J. Franke, NanoLetters 13, 4840
(2013)
Wednesday, August 27, 2014, San Sebastián, Spain
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Magnetic Coupling of Tm and Lu Adatoms with Fe Monoatomic Islands
on W(110): Spin-polarized Tunneling Microscopy and Ab-initio
Calculations
1
1
1
1
1
1
D. Coffey , J. L. Diez-Ferrer , D. Serrate , M. Ciria , C. de la Fuente , J. I. Arnaudas
1
Universidad de Zaragoza
In Rare Earth-Transition Metal (RE-TM) compounds the RE-TM magnetic interaction proceeds
via an indirect mechanism in which the 5d electrons act as the intermediary.[1] When the 5d
band is less than half full and the 3d band is more than half full, the case of RE-(ferromagnetic
TM) compounds, the 5d-3d exchange is antiferromagnetic and the RE and TM spins couple
antiparallel. Here, we report on an extreme situation, where only adatoms of RE are adsorbed
on a TM ferromagnetic monolayer. We have investigated with scanning tunneling microscopy
and spectroscopy Thulium and Lutetium adatoms, deposited on iron monolayer islands, with
in-plane magnetization [2], pseudomorphically grown on a clean W(110) substrate under ultrahigh vacuum conditions, at low temperature. The spin polarized differential conductance
images (Fig. 1), obtained with an Fe covered tungsten tip and taken both at constant height
and at constant current, show that Tm and Lu present a contrast opposite to the one shown by
the respective Fe islands beneath. A possible dependence on the spin polarization shown by
the adatom on the energy and vertical distance to the tip [3] has been discarded by performing
the measurements at different bias and heights without appreciable modification of the
reversed contrast observed between the adatom and the island. First principles calculations
show that the Lu and Tm 5d moments lie in plane and couple antiferromagnetically with their
underlying iron islands, in agreement with the Campbell model even at the single atom limit.
[1]. I. A. Campbell, J. Phys. F Met. Phys. 2, L47 (1972).
[2]. N. Weber et al., Phys. Rev. B 55, 14121 (1997).
[3]. N. Néel et al., Phys. Rev. B 85, 155406 (2012).
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Effects Of The Kondo Coupling On Magnetic Adsorbates On Surfaces
1
F. Delgado , Joaquín Fernández-Rossier
1
1
D
INL-International Iberian Nanotechnology Laboratory, Braga (Portugal)
N
Scanning Tunneling Microscope (STM) makes it possible to fabricate and probe magnetic
nanostructures with atomic resolution, going from individual atoms up to arrays of spin chains.
These systems lie in the borderline between two opposite regimes, the quantum, reflected in
the discrete nature of the spin excitations apparent in the inelastic electron tunneling
spectroscopy (IETS), and classical, with finite magnetization. The displayed regime depends not
only on their size [1,2], but also on the strength of their coupling to the environment.
Thus, the theoretical description of these magnetic adsorbates requires to deal with both, the
quantum nature and the coupling to the environment. The first is accounted for by an effective
spin Hamiltonian [1-4]. The energy and momentum transfer can be then described by an
exchange coupling with the adsorbate spin. In weakly coupled systems, the dynamics of the
adatoms can be study using a perturbative treatment of the exchange coupling together with a
master equation for the reduced density matrix. This treatment correctly depicts the observed
features in IETS while it allows identifying the decoherence and relaxation mechanisms [3]. It
has further succeeded in explaining the magnetoresistive response when the adatoms are
probed by a spin-polarized STM tip [3] or the observed energy shift when the exchange
coupling is modulated along the substrate [4].
1. S. Loth, S. Baumann, C. P. Lutz et al., Sience 335, 196 (2012)
2. F. Delgado et al, in preparation
3. F. Delgado and J. Fernández-Rossier, Phys. Rev. B 82, 134414 (2010)
4. J. C. Oberg, M. R. Calvo, F. Delgado et al., Nature Nanotechnology 9, 64 (2014).
Magnetic Force Microscopy Imaging In Liquid
P. Ares1,2, M. Jaafar3, A. Gil1, J. Gómez-Herrero2, A. Asenjo3
1
2
Nanotec Electrónica S.L., Tres Cantos (Madrid), Spain Dpto. Física de la Materia Condensada 3
Universidad Autónoma de Madrid, Madrid, Spain Instituto de Ciencia de Materiales de Madrid - CSIC,
28049, Madrid, Spain
In this work, we present Magnetic Force Microscopy (MFM) images acquired in liquid
environment. As is well known, MFM in liquid is a challenge as a consequence of the low
quality factor (Q) of the cantilever resonance characteristic of liquid measurements. This low Q
results in a significant loss of sensitivity in the MFM signal. Nevertheless, the capability of
measuring magnetic nanostructures in liquid environment starts up new strategies in the
characterization of nanoparticles for cancer treatment, or in vitro biological magnetic material
of high interest in nanomedicine, as for instance viral cages with a magnetic cargo.
We use a Nanotec Electrónica AFM system controlled by WSxM software [1]. As a benchmark
for this work we use a high density magnetic hard disk drive (Samsung HM320JI) with magnetic
motif of ~60 nm. Commercial MFM probes (Nanosensor PPP-MFMR) are used. For the sake of
comparison we first acquire MFM images in air ambient conditions in both Amplitude (AMWednesday, August 27, 2014, San Sebastián, Spain
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AFM) and Drive Amplitude (DAM-AFM) Modulation modes [2, 3], obtaining similar results. For
the images in liquid environment we use a specially designed acoustic driver cantilever holder
[4] to minimize the resonance forest peak characteristic of acoustic drive in liquids. The lift
distances used during the MFM signal recording are 15 nm in air and 6 nm in liquid.
Figures 1 a and b show two magnetic signal images acquired in air ambient conditions at two
different oscillation amplitudes (10 and 5 nm), where a clear magnetic contrast between the
different bits of the surface can be readily observed. Figures 1 c and d show the corresponding
MFM images taken in liquid environment (images in air and liquid are acquired in different
regions of the hard drive surface), where, despite the reduction in the signal-to-noise ratio (see
inset profiles), the magnetic contrast can be easily seen as well, keeping a good lateral
resolution.
The magnetic contrast observed in liquid environment in our work has been highly optimized
[5]. In the presentation we discuss the origin of this optimization that will allow the study of a
variety of magnetic materials in liquid.
I Horcas et al, Review of Scientific Instruments 78 (2007) p.013705
R García and R Pérez, Surface Science Reports 47 (2002) p.197-301
M Jaafar et al, Beilstein Joural of Nanotechnology 3 (2012) p.336-344
C Carrasco et al, Review of Scientific Instruments 79 (2008) p.126106
R Giles et al, Applied Physics Letters 63 (1993) p.617
State Of A Single Molecule By Local Gating On A Semiconductor
Surface
1
1
2
3
Jesús Martínez-Blanco , Christophe Nacci , Kyoshi Kanisawa , Steven Erwin , Stefan
Fölsch
1
1
2
Paul-Drude-Institut für Festkörperelektronik. Berlin, Germany NTT Basic Research Laboratories.
3
Atsugi, Japan Center for Computational Materials Science, Naval Research Laboratory. Washington
D.C., USA
InAs(111)A is a semiconductor surface that provides a unique playground in which the charge
state of any adsorbed object, like an adatom or a molecule, can be probed directly by
measuring the local surface band bending induced by the charged object. At the same time,
the surface electrostatic potential can be tailored locally by indium adatoms, which can be
manipulated at 5 K with the STM tip, and which remain positively charged on the surface due
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to their donor character. Taking advantage of these features, we study the charge state of
single phthalocyanine molecules adsorbed on this surface. We engineer the electrostatic
potential around the molecule by constructing different indium nanostructures nearby. In this
way we are able to apply a gating potential to the surface-molecule-tip system. Tuning this
gating potential appropriately, we observe a charge bistability at the location of the molecule
for bias voltages around zero volts, transforming it into a single molecule charge switcher. We
provide a full characterization of this system and discuss the possible mechanisms leading to
its bistability.
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Vector Mapping Of The Magnetic Moment Of Individual Atoms Using
Spin Polarized STM
1
2
3
1
1
M. Moro , M. Piantek , J. I. Pascual , M. R. Ibarra , D. Serrate
1
Instituto de Nanociencia de Aragón (INA) and Laboratory for Advanced Microscopy (LMA), University of
Zaragoza, Spain 2 Instituto de Ciencias de Materiales de Aragón (ICMA), University of Zaragoza-CSIC,
Spain 3 Nanoscience Cooperative Research Center (CIC Nanogune)
Understanding and controlling the magnetic state of adatoms on a surface is of crucial
importance in the development of spin based technology. Research in this field calls for a
suitable technique able to observe and manipulate the spin of magnetic impurities. For that
purpose we use spin polarized scanning tunneling microscopy (SP-STM), combining high
magnetic lateral resolution and atom manipulation capability. In SP-STM, the magnetization
easy axis of the tip determines the spin direction sensitivity for the sample system [1]. The
tunneling magnetoresistance effect, upon which SP-STM relies, precludes sensing
simultaneously two orthogonal spin directions of the sample with the same tip. In this work,
we demonstrate that the easy axis of the SP-tip can be changed controllably from in-plane to
out of plane and viceversa. This is achieved by transferring a single Co atom to a Fe coated W
tip or dropping it by means of vertical manipulation methods. In the range of one monolayer
on W(110), Mn orders magnetically as an antiferromagnetic spin spiral propagating along the
[1-10] direction [2]. Such magnetic structure gives rise to a distinct spin resolved contrast that
allows us to measure the evolution the SP-tip sensitivity direction. Besides, Co atoms placed at
17
designated positions over the spin-spiral display an apparent shape and height strongly
dependent on their spin direction [3]. The changes observed in the tip magnetization direction
upon picking/dropping a Co atom are further confirmed attending at the spin resolved contrast
of the atoms remaining on the surface.
Our results show that a controlled rotation of 90° in the magnetization direction of a SPtip is
possible, giving rise to a powerful tool for the characterization of novel magnetic materials in
absence of magnetic field.
Kubetzka, A. et al. PRL 88, 57201 (2002)
Bode, M. et al. Nature 447, 190-193 (2007)
Serrate, D. et al. Nature Nanotechnology 5, 350-353 (2010)
On-Surface Synthesis Of BN/Graphene Hybrid Structures
1
2
2
3
Carlos Sanchez-Sanchez , Matthias Müller , Holger F. Bettinger , Sebastian Brüller ,
3
1
1
1
Klaus Müllen , Leopold Talirz , Carlo Pignedoli , Pascal Ruffieux , Roman Fasel
1
1
Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600
2
Dübendorf, Switzerland Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18,
3
72076 Tübingen, Germany Max Planck Institute for Polymer Research, 55128 Mainz, Germany
The absence of an electronic band gap is a major obstacle to the fabrication of efficient
graphenebased switching devices. Different strategies, including top-down structuring and
chemical modifications, have been proposed to transform graphene into a semiconductor [1].
However, most of these strategies lack accurate control on the resulting structures. Atomic
level accuracy can be achieved by bottom-up strategies based on the surface-assisted
colligation and transformation of suitably designed precursor monomers, which has proven to
yield atomically precise surfacesupported nanoarchitectures. For instance, fullerenes and
azafullerenes, nanodomes, and nanographenes have been synthesized via Surface-Assisted
Cyclodehydrogenation (SACDH). Furthermore, the combination of SACDH with surfacecatalyzed Ullmann coupling has been used for the synthesis of atomically precise graphene
nanoribbons (GNR) and porous graphene, where electron confinement yields the appearance
of a band-gap [2,3]. Here we will show how the combination of SACDH and Ullmann coupling
on metallic surfaces under ultra-high vacuum conditions allows for the formation of 2D
BN/graphene hybrid networks, which are unavailable via traditional solution-based chemistry.
We find that high-resolution scanning tunneling microscopy (STM) images together with
density functional theory calculations allow the identification of the position and orientation of
the borazine rings. Our proof-of-concept study opens the door towards the design and
synthesis of atomically precise heterostructures by tailoring of precursor monomers.
[1] D. Jariwala, A. Srivastava and P. M. Ajayan. http://arxiv.org/ftp/arxiv/papers/1108/1108.4141.pdf
[2] J. Mendez, M. F. Lopez, J.A. Martin-Gago, Chem. Soc. Rev., 2011, 40, 4578-4590.
[3] J. Björk, and F. Hanke, Chem. Eur. J. 2014, 20, 928 – 934.
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Charge-transfer Induced Isomerization Of DCNQI On Cu(100)
1
1,2
1
3
1
A
2,3
C. Urban , Y. Wang , J. Rodríguez-Fernández , M. A. Herranz , M. Alcamí , N. Martín ,
1,2
2,4
1,2
F. Martín , J. M. Gallego , R. Otero , R. Miranda
1
1,2
Universidad Autónoma de Madrid. Madrid. 2 IMDEA-Nanociencia. Madrid. 3 Universidad Complutense
de Madrid. Madrid. 4 ICMM-CSIC. Madrid.
Cis-trans isomerization reactions have been recently proposed as models for the action of
molecular-scale switches. Molecules like azobenzene derivatives have thus been deposited on
solid surfaces and the isomerization reaction has been induced by external influences such as
the tunneling current of an STM or light irradiation. Although the catalytic action of the surface
on such reactions is amply acknowledged in previous works, understanding the exact
mechanism of such reactions still requires further studies. Moreover, the effect of
temperature on such reaction has not been studied at any extent. Here we show STM and DFT
results on the thermally-controlled isomerization of the DCNQI molecules adsorbed on
Cu(100). Depending on the substrate temperature two different molecular arrangements are
observed, along with two different appearances of the molecules in STM images. Comparison
with DFT calculations shows that whereas the low-temperature phase is consistent with a
trans-geometry of the cyano groups with respect to the molecular axis, at higher temperatures
such arrangement is formed exclusively with cis-isomers. The transition temperature, -30°C, is
too low for the molecule in the neutral form to undergo such cis-trans isomerization, and thus
a catalytic effect of the substrate must exist. Based on our experimental results and theoretical
calculations we attribute such catalytic effect to charge-transfer from the metal to the
molecule along with a strong bonding between the cyano groups and the copper atoms of the
substrate. Charge-transfer lowers the cis-trans isomerization barrier in two synergistic ways.
First it aromatizes the quinoid ring into a benzene ring, enabling a freer rotation of the cyano
groups with respect to the molecular axis. Second, such easier rotation leads to an enhanced
interaction of the cyano groups with the copper atoms of the substrate that brings the two
isomeric forms closer to each other than in the gas phase conformation
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Theoretical STM Characterization Of On-surface Reactions Of
Heteroaromatics
1
1
1
Jose Ignacio Martinez , Anna Lisa Pinardi , Gonzalo Otero-Irurueta , Maria Francisca
1
1
1
Lopez , Javier Mendez , Jose Angel Martin-Gago
1
Dept. de Superficies y Recubrimientos (ICMM / CSIC), ES-28049 Madrid, Spain
Understanding the interaction between organic molecules and surfaces is of paramount
importance in diverse fields such as organic electronics, molecular electronics, catalysis, and
surface photochemistry, among others. In particular, the bottom-up approach aims at forming
tailored nanoarchitectures by manipulating organic molecules at atomic level and it is one of
the most effective strategies used in nanotechnology. Catalytic surfaces are often used to
prompt a particular reaction as they are very successful in modifying a particular molecule in
selected ways. For example, transition metal surfaces are very efficient catalysts of
dehydrogenation reactions in Polycyclic Aromatic Hydrocarbon (PAH), usually upon thermal
activation. They can act in different ways, depending on the strength of the interaction
between the surface and the adsorbate [1]. When a PAH is deposited on a reactive surface,
such as Pt(111), the molecule does not diffuse, so the as-deposited molecule sticks where it
lands. When this system is annealed, the molecule dehydrogenates which results in an
intramolecular transformation, as no intermolecular interaction is allowed as the molecules do
not “see” each other. An adequate combination of first-principles calculations, including vdW
interactions, with an accurate theoretical STM imaging approach based on the Keldish-Green
formalism [2], permits the monitoring and full characterization of the different intermediate
steps along the whole thermal-induced dehydrogenation process [1]. Following this line, our
research group has recently shown the catalytic properties of the TiO2 (110)-(1×1) surface
towards dehydrogenation of large organic molecules [3]. In this case, we have deposited
C60H30 molecules on this surface and we have proven that high temperature annealing leads
to partial cyclodehydrogenation, which allows the use of the activated PAHs as building blocks
for larger nanostructures. In this way, the formation of fullerene-like nanodomes on this
dielectric surface was observed by STM. The different stages of this on-surface chemistry were
followed by different experimental techniques (STM, XPS and NEXAFS), and fully characterized
by the mentioned theoretical framework. For this particular interface, theory shed some light
on the origin of the two different sets of molecules observed in the UHV-STM images, one
vanishing for certain values of the external tunnelling bias, and the other set of molecules
observed at all range of bias, which is directly related to the dehydrogenation stage of the
molecules [3].
A. L. Pinardi, J. I. Martínez, J. A. Martín-Gago et al., ACS Nano 7(4), (2013) 3676; Chem. Comm. 50, (2014)
1555.
J. P. Lewis et al., Phys. Stat. Sol. B 248, (2011) 1989; J. M. Blanco et al., Phys. Rev. B 70, (2004) 085405.
C. Sánchez-Sánchez, J. I. Martínez, J. A. Martín-Gago et al., Nanoscale 5, (2013) 11058.
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Customizing Metallocene layers on Cu(111)
1
1
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2
3
Ormaza Maider , Bachellier Nicolas , Bocquet Marie-Laure , Lorente Nicolas , Limot
D
Laurent
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1
Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS-UdS, 67034 Strasbourg, France
E
2
Université de Lyon, Laboratoire de Chimie, Ecole Normale Supérieure de Lyon, CNRS, France
S
3
Centro de Investigación en Nanociencia y Nanotecnología (CSIC-ICN), Bellaterra E-08193, Spain
Metallocene double-decker molecules have received considerable interest over the past two
decades due to their application as catalysts and organometallic polymers with magnetic
properties. More recently, it has been predicted that these molecules present unique spin
transport properties, behaving in fact as halfmetallic ferromagnets [1]. Despite this promising
prediction, electron transport across metallocene molecules is yet to be explored.
Here we use Scanning Tunneling Microscopy (STM) to characterize the adsorption and
electronic properties of ferrocene (FeCp2, Cp=C5H5) and cobaltocene (CoCp2) on metallic
surfaces. In particular, we show, with the support of DFT, that these molecules self-assemble
forming ordered molecular monolayers (fig. 1) and that the nature of the central atoms plays
an important role determining the molecular self-assembly. Most importantly, we
demonstrate that the deposition of adatoms onto the molecular layer leads to the formation
of novel triple-decker molecules which carry a Kondo effect.
Fig. 1: FeCp2 network with cobalt atoms (-1V, 0.5 nA)
[1]. L. Wang et al., Nano Lett. 8, 3640 (2008)
Electron Scattering Of Rashba-split States In The BiAg2 Surface Alloy
7
7
6
S. Schirone , R. Piquerel , G. Bihlmayer , E. E. Krasovskii
Mugarza
1
7
3,4,5
, P. Gambardella
1,2,7
, A.
2
ICREA - Institucio Catalana de Recerca i Estudis Avancats, E-08193 Barcelona, Spain Department of
3
Materials, ETH Zurich, Hönggerbergring 64, CH-8093 Zurich, Switzerland Dpto. de Física de Materiales
4
UPV/EHU, Facultad de Quimica, Paseo Manuel de Lardizabal 3, E-20018, San Sebastián, Spain Donostia
International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, E-20018 San Sebastián, Spain
5
6
IKERBASQUE, Basque Foundation for Science, E-48011 Bilbao, Spain Institute for Advanced Simulation
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and Peter Grünberg Institut 1, Forschungszentrum Jülich, D52425 Jülich, Germany ICN2 - Institut Catala
de Nanociencia i Nanotecnologia, Campus UAB, E-08193 Bellaterra (Barcelona), Spain
Spin-orbit interaction (SOI) in metallic surfaces can lead, via the Rashba effect, to a splitting of
the spin degeneracy and the emergence of particular spin textures that are related to the
entanglement between spin and orbital momentum. Here we use the BiAg2 surface alloy,
which is characterized by the strongest to date Rashba effect [1,2], to study the effect of SOI
on scattering. The alloy is formed on the Ag(111) surface after the deposition of 1/3 monolayer
of Bismuth. The scattering has been studied using Scanning Tunnelling Microscopy and
Spectroscopy (STM/STS). In this way we have studied electron confinement by measuring the
interference patterns formed by surface electrons scattered from monoatomic steps. We find
that scattering is determined by i) an unconventional orbital/spin texture of the surface bands,
which give rise to transitions with combined orbital and spin flips, and ii) by its chemical
composition, which defines a heterogeneous electron localization and potential landscape. The
negligible leakage we observe across some step structures indicate a strong confinement
effect, comparable to that observed in metals with marginal SOI such as Ag
(111) [3]. The results describe a scenario that is far more complex than the conventional
Rashba-type two dimensional free-electron gas.
Figure 1: (a) Topographic image of a zone of the sample with different type of monoatomical step,acquired with
I_t=0.59 nA and V_bias =0.2 V . Image size: 406×406 Å^2. (b) dI⁄dV-map acquired acquired at V_bias =+0.4 V . Note
that the intensity of the standing wave scattered from the two kind of steps is different. (c) Topographic image
performed with I_t= 0.59 nA . V_bias= 28 mVImage size: 164×110 Å^2. The surface lattice structure is resolved in
the image, and the different termination of each step type can be distinguished. (d) Schematics of the lattice of the
surface alloy. Solid lines indicate the direction of each step type.
C. Ast, J. Henk, A. Ernst, L. Moreschini, M. C. Falub, D. Pacile, P. Bruno, K. Kern, and M. Grioni, Phys. Rev. Lett.
98, 186807 (2007).
G. Bihlmayer, S. Blügel, and E. V Chulkov, Phys. Rev. B 75, 195414 (2007).
J. E. Ortega, J. Lobo-Checa, G. Peschel, S. Schirone, Z. M. Abd-El-Fattah, M. Matena, F. Schiller, P. Borghetti, P.
Gambardella, and A. Mugarza, Phys. Rev. B 87, 115425 (2013).
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Graphene tunable electronic tunneling transparency: A unique tool to
measure the local coupling
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2
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2
H. González-Herrero , A.J. Martínez-Galera , M.M. Ugeda , F. Craes , D. FernándezTorre3, P. Pou3, R. Pérez3, J.M. Gómez-Rodríguez1 and I. Brihuega 1.
1
Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany 3 Dept. de
Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid,,Spain
Graphene grown on metals has proven to be an excellent approach to obtain high quality
graphene films [1,2]. However, special care has to be taken in order to understand the
interaction of graphene with the substrate, since it can strongly modify its properties even in
apparently weakly coupled systems [3]
Here, we have grown one monolayer graphene on Cu (111) by using a new technique
consisting in the thermal decomposition of low energy ethylene ions irradiated on a hot
copper surface [4]. By means of low temperature STM/STS experiments, complemented by
density functional theory calculations, we have obtained information about the structural and
electronic properties of our graphene samples with atomic precision and high energy
resolution. Our work shows that depending on the STM tip apex and the tunnel parameters we
can get access to either the graphene layer, the copper surface underneath or even both at the
same time, see Figure 1. This fact provides a unique tool to investigate the local coupling
between the graphene layer and the metal underneath. Moreover, this approach can also be
applied to investigate the interaction of point defects in the graphene layer with the
underlying substrate [5].
Tunneling
to Cu(111)
Figure 1: Same 60x60 nm2 terrace measured with different tunneling conditions. Left side: the moiré pattern of
the graphene layer is observed. Right side: the standing-waves patterns associated with the Cu(111) surface state
below the graphene layer are observed. Both images are measured at 6K
[1].
[2].
[3].
[4].
[5].
J. Wintterlin and M. L. Bocquet, Surf. Sci. 603, 1841(2009).
X. S. Li et al., Science, 324, 1312 (2009).
I. Brihuega, P. Mallet, H. González-Herrero et al. Phys. Rev. Lett. 109, 196802 (2012).
A.J. Martínez-Galera, I. Brihuega and J. M. Gómez-Rodríguez, Nano Letters 11, 3576 (2011).
M. M. Ugeda, D. Fernández-Torre, I. Brihuega et al., Phys. Rev. Lett. 107, 116803 (2011).
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Dept. Física de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 , Spain II.
Tunneling
to graphene
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Graphene Etching On SiC Grains As A Path To Interstellar Polycyclic
Aromatic Hydrocarbons Formation
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P. Merino , M. Švec , J.I. Martinez , P. Jelinek , P. Lacovig , M. Dalmiglio , S. Lizzit , P.
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Soukiassian , J. Cernicharo , J.A. Martin-Gago
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Centro de Astrobiología INTA-CSIC, Carretera de Ajalvir, km.4, ES-28850 Madrid, Spain Institute of
Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, CZ-16200 Prague, Czech Republic
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Instituto Ciencia de Materiales de Madrid-CSIC, c/. Sor Juana Inés de la Cruz, 3, ES-28049 Madrid, Spain
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Elettra-Sincrotrone Trieste S.C.p.A., Area Science Park, S.S. 14, Km 163.5, I-34149 Trieste, Italy
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Commissariat à l’Energie Atomique et aux Energies Alternatives, SIMA, DSM-IRAMIS-SPEC, Bât. 462,
91191 Gif sur Yvette, France
Polycyclic aromatic hydrocarbons as well as other organic molecules appear among the most a
bundant observed species in interstellar space and are key molecules to understanding the
prebiotic roots of life. However, their existence and abundance in space remain a puzzle. Here
present a new top-down route to form polycyclic aromatic hydrocarbons in large quantities in
space. We show that aromatic species can be efficiently formed on the graphitized surface of
the abundant silicon carbide stardust on exposure to atomic hydrogen under pressure and
temperature conditions analogous to those of the interstellar medium. To this aim, we mimic
the circumstellar environment using ultra-high vacuum chambers and investigate the SiC
surface by in situ advanced characterization techniques combined with first-principles
molecular dynamics calculations. These results suggest that top-down routes are crucial to
astrochemistry to explain the abundance of organic species and to uncover the origin of
unidentified infrared emission features from advanced observations.
Figure: False color STM image of a hole in the middle of a graphene terrace. These holes are observed after H
treatment at high temperatures and evidence etching through edges and defects. 70x70nm2,-1.1V.
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Observation Of Giant Bandgap Renormalization And Excitonic Effects
In A Monolayer Transition Metal Dichalcogenide Semiconductor
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Miguel M. Ugeda , Aaron J. Bradley , Su-Fei Shi , Felipe H. da Jornada , Yi Zhang ,
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Diana Y. Qiu , Sung-Kwan Mo , Zahid Hussain , Zhi-Xun Shen , Feng Wang , Steven
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G. Louie , Michael F. Crommie
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Department of Physics, University of California at Berkeley, Berkeley, CA, USA. 2 Materials Sciences
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Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. Advanced Light Source, Lawrence
Berkeley National Laboratory, Berkeley, CA, USA. 4 Stanford Institute for Materials and Energy Sciences,
SLAC National Accelerator Laboratory, Menlo Park, CA, USA. 5 Geballe Laboratory for Advanced
Atomically-thin transition metal dichalcogenide (TMD) semiconductors have generated great
interest recently due to their remarkable physical properties. For example, reduced screening
in 2D has been predicted to result in dramatically enhanced Coulomb interactions that should
cause giant bandgap renormalization and excitonic effects in single-layer TMD semiconductors.
[1, 2]. Here we present a direct experimental observation of extraordinarily high exciton
binding energy and band structure renormalization in a single-layer of semiconducting TMD
[3]. We determined the binding energy of correlated electron-hole excitations in monolayer
MoSe2 grown on bilayer graphene (BLG) using a combination of high-resolution scanning
tunneling spectroscopy (STS) and photoluminescence spectroscopy. We have measured both
the quasiparticle electronic bandgap and the optical transition energy of monolayer
MoSe2/BLG, thus enabling us to obtain an exciton binding energy of 0.55 eV for this system, a
value that is orders of magnitude larger than what is seen in conventional 3D semiconductors.
We have corroborated these experimental findings through ab initio GW and Bethe-Salpeter
equation calculations which show that the large exciton energy arises from enhanced Coulomb
interactions that lead to a dramatic blue-shifting of the quasiparticle bandgap. In addition, we
explored the low-energy electronic structure of single- and few-layer MoSe2. Our results
reveal that the electronic properties of these materials are highly dependent on the number of
layers (4). These results are of fundamental importance for the design and evaluation of roomtemperature electronic and optoelectronic nanodevices involving single-layer semiconducting
TMDs. This includes all optoelectronic applications, such as solar cells and new valleytronic
schemes, either in stand-alone devices or within integrated heterostructures. More
fundamentally, the excitonic nature of the optical response for single-layer MoSe2 highlights
the importance of many-body effects in atomically-thin 2D layers.
H. P. Komsa, A. V. Krasheninnikov, Physical Review B. 86, 241201 (2012).
D. Y. Qiu, F. H. da Jornada, S. G. Louie, Physical Review Letters. 111, 216805 (2013).
M. M. Ugeda, A. J. Bradley, et al., Submitted.
A. J. Bradley, M. M. Ugeda, et al., Manuscript in preparation.
Electrostatic Manipulation Of Graphene On Graphite
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C. Rubio-Verdú , J. Martínez , M.J. Caturla , G. Sáenz-Arce , D. C. Milán , C. Untiedt
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Department of Applied Physics, University of Alicante
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Here we report the use of a Scanning Tunneling Microscope (STM) under ambient and vacuum
conditions to study the controlled exfoliation of the last layer of a graphite surface when an
electrostatic force is applied from a STM tip. In this work we have focused on the study of two
parameters: the applied voltage needed to compensate the graphite interlayer attractive force
and the one needed to break atomic bonds to produce folded structures.
Additionally, we have studied the influence of edge structure in the breaking geometry.
Independently of the edge orientation the graphite layer is found to tear through the zig-zag
direction and the lifled layer shows a zig-zag folding direction.
Molecular Dinamics simulations have been performed showing a strong correlation with the
experimental results.
AFM Technologies in personolized medical diagnostics
Christoph Gerber
Swiss Nanoscience Institute, Institute of Physics, University of Basel, Switzerland
Recently Atomic Force Microscopy (AFM) technologies have come of age in various biological
applications. Moreover these developments has started to enter the clinic .From this
nanotoolkit we use a micro-fabricated silicon cantilevers array platform as a novel biochemical
highly sensitive sensor that offers a label-free approach for point of care fast diagnostics
where ligand-receptor binding interactions occurring on the sensor generate nanomechanical
signals like bending or a change in mass which is optically detected in-situ. It enables the
detection of multiple unlabelled biomolecules simultaneously down to picomolar
concentrations within minutes in differential measurements including reference cantilevers on
an array of eight sensors. The sequence-specific detection of unlabelled DNA in specific gene
fragments within a complete genome is shown. In particular the expression of the inducible
gene interferon- a within total RNA fragments and unspecific back ground . This gives rise that
the method allows monitoring gene regulation , an intrinsic step in shining light on disease
progression on a genetic level. Moreover malignant melanoma, the deadliest form of skin
cancer can be detected with this technology on a single point mutation without amplification
and labeling in the background of the total RNA
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Looking back 30 years at Baro’s Laboratorio de Nuevas Microscopías:
the recollections of a mid-western American
Ron Reifenberger
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Purdue University, Department of Physics, West Lafayette IN USA
I will provide a retrospective look back at Prof. A.M. Baro’s role in promoting scanning probe
research in mid-western America. Spanning the unbelievable days just after the STM was
invented to the present, I will hi-light joint research between Baro’s lab at UAM and the
scanning probe research conducted at Purdue University to illustrate the fruits of a 30 year,
life-long international collaboration. In addition to a recitation of various scientific
achievements, the talk includes photos and recollections of ‘la forma en que fue’ which will
support the hypothesis that we should judge our life by the memories, not by the years.
Scanning the trends of Atomic Force Microscopy
Arvind Raman
Robert V. Adams Professor of Mechanical Engineering,
Purdue University, Department of Physics, West Lafayette IN USA
The American baseball great Yogi Berra once reputedly said “The future ain’t what it used to
be” referring to the pitfalls of using trends to predict the future. So too can be said of the field
of AFM. The last two decades have seen an astonishing number of technological innovations,
some that have staying power and others that are no longer popular. And yet the AFM has
advanced much in the past two decades. In this talk we will discuss some of these past and
present trends with a view to learning from these examples. We will discuss competing
microscopies and broad tendencies in the AFM field today that may suggest near future
directions in the field at very broad level.
Tunneling Microscopy: Retrospectives and perspectives
Ignacio Pascual
CIC Nanogune, Donosti-San Sebastián, Spain
Arturo Baró was witness and actor of the born and development of probe microscopies during
the last three decades. During this time, tunneling microscopes spanned in areas of chemistry
and physics with such strong impact that changed in many respects our approach do science.
This “new science”, the “Science of the Local Information in the Real Space”, manipulates
mater at the atomic scale, measures electrons in reciprocal space, and currently advances to
cover frequency and time domains. A retrospective of its development entails an overview of
classical problems in condensed matter and physical-chemistry, to which local probes
contributed to advance. In this talk, I will give a very personal retrospective of Tunneling
Microscopy and Spectroscopy beyond imaging, as well as trends and perspectives for the
coming years.
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Realising quantitative dynamic atomic force microscopy to probe
transactions of DNA at the single molecule level
Neil H Thomson1,2
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Department of Oral Biology, School of Dentistry Molecular and Nanoscale Physics Group, School of
Physics and Astronomy, University of Leeds, LS2 9JT, United Kingdom.
The dynamic modes of atomic force microscopy (dAFM), where the force sensing cantilever is
oscillated at or close to resonance, have been essential for atomic force microscopy to reliably
image and measure soft biological samples, from single molecules to cells. Extracting
quantitative information has been hampered by a number of problems, including
understanding the dynamics of the oscillating cantilever in the non-linear tip-sample potential
and the response of the cantilever from the integration of forces of different origin (sign and
length scale) by the AFM tip.
The first part will summarise a number of key advances our group has made towards making
AFM measurements quantitative. It will demonstrate that loss of height at the nanoscale is a
consequence of the intrinsic convolution between the force fields of the tip and sample [1]. A
new in situ tip sizing technique was developed based on the bi-stable behaviour of the
oscillating cantilever above the sample [2]. We have also shown that for DNA on hydrophilic
surfaces such as mica, even in ambient conditions, there is sufficient water present to retain
structural hydration of biomolecules [3]. Building on these three outcomes, we have been able
to measure the hydrophilicity of individual DNA molecules, which indicates that DNA may be
more hydrophobic than previously anticipated [4]. Furthermore, we have implemented a new
imaging mode that maximises resolution and can resolve the right-handed DNA double helix in
ambient [5].
The second part will concentrate on the use of amplitude modulation (AM AFM) imaging
applied to DNA-protein complexes in ambient conditions. We are studying DNA transcription
and investigating dual RNA polymerase transactions on single DNA templates in the context of
the twin supercoiling domain paradigm [6]. The outcomes have implications for compressed
genetic structures found in vivo and are giving foundation to understanding the “rules of the
road” for these molecular motors that mediate gene expression.
Santos S., Barcons V., Christenson H.K., Font J. and Thomson N.H. (2011) PLoS ONE 6 (8): e23821.
Santos S., Guang L., Souier T., Gadelrab K., Chiesa M. and Thomson N.H. (2012) Rev. Sci. Instrum. 83, 043707.
Billingsley D.J., Kirkham J., Bonass W.A, and Thomson N.H. (2010) Phys. Chem. Chem. Phys. 12 (44), 14727 14734
Santos S., Stefancich M., Hernandez H., Chiesa M. and Thomson N.H. (2012) J. Phys. Chem. C 116 (4) 28072818.
Santos S., Barcons V., Christenson H.K., Billingsley D.J., Bonass W.A, Font J. and Thomson N.H. (2013) Applied
Physics Letters 103, 063702.
Billingsley D.J., Bonass W.A, Crampton N., Kirkham J. and Thomson N.H. (2012) Physical Biology 9, 021001.
Thrusday, August 28, 2014, San Sebastián, Spain
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Imaging Of Biosystems By Dynamic Atomic Force Microscopy
Magali Phaner-Goutorbe
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Université de Lyon, Institut des Nanotechnologies de Lyon (INL, UMR CNRS 5270), site Ecole Centrale
de Lyon, 36 avenue Guy de Collongue, 69134 Ecully, France E-mail: [email protected]
Using amplitude-mode AFM (AM-AFM), valuable information has been obtained during these
recent years through the study of amplitude and phase shift dependence on tip-sample
separation, leading to a comprehensive understanding of the interaction processes. Two
imaging regimes, attractive and repulsive, have been identified and a relationship between
phase and dissipative energy was established, providing information on observed material
properties. Most of the previous studies have concerned model systems: either hard or soft
materials [1-3].
In the case of biosystems, the sample is composed of biological macromolecules or thin
bio/organic layers supported on mineral substrates. Then, this creates a mixed system of soft
structures on a hard substrate. In this work, we propose to discuss about the dynamics of
dissipation processes during scanning based on a real biosensor a DNA array, and
demonstrated that information about the tip-surface interaction regime can be obtained [4].
The best experimental conditions to obtain specific information were determined: we got
reliable conditions to minimize noise during topographic imaging and an understanding of the
processes of energy dissipation involved in the DNA breaking for DNA arrays. By calculating the
energy dissipated as a function of the amplitude of oscillation, we have demonstrated a
transition from an energy dissipation process governed by localized viscoelastic interactions
(due to the soft layer) to a process governed by extended irreversible deformations (due to the
hard substrate). Examples of other biosystems were also presented [5, 6].
R. García, R. Pérez, Surf. Sci. Rep. 47, 197, (2002).
N. F. Martínez, W. Kamiński, C. J. Gómez, C. Albonetti, F. Biscarini, R. Pérez, R. García, Nanotechnology 20,
434021, (2009).
R. Garcia, C. J. Gomez, N.F. Martinez, S.Patil, C.Dietz, R. Magerle, Phys. Rev. Lett. 97, 016103, (2006).
M. Phaner-Goutorbe, M. Iazykov,R. Villey, D. Sicard, Y. Robach, Materials Science and Engineering C 33, 23112316, (2013)
D. Sicard, Y. Chevolot, E. Souteyrand, S. Vidal, M. Phaner-Goutorbe, J. Mol. Recognit., 26, 694, (2013)
D. Sicard, S. Cecioni, M. Iazykov, Y. Chevolot, S. Mathews, J-P. Praly, E. Souteyrand, A. Imberty, S.Vidal, M.
Phaner-Goutorbe, Chem. Commun., 47 (33), 9483 – 9485, (2011)
Fast Nanomechanical Spectroscopy of Soft Matter
E. T. Herruzo, A.P. Perrino , R. Garcia
Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Madrid
A method that combines high spatial resolution, quantitative and non-destructive mapping of
surfaces and interfaces is a long standing goal in nanoscale microscopy. The method would
facilitate the development of hybrid devices and materials made up of nanostructures of
different properties.
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Bimodal atomic force microscopy is a multifrequency dynamic force method based on the
simultaneous excitation of two eigenmodes of the cantilever [1,2]. We have developed a
multifrequency force microscopy method that enables the simultaneous mapping of the
nanomechanical spectra of soft matter surfaces with nanoscale spatial resolution [3,4]. The
properties include the Young modulus and the viscous or damping coefficients. In addition, it
provides the peak force and the indentation. The method has been tested on different
polymers and proteins in air with near four orders of the magnitude variations in the elastic
modulus, from 1 MPa to 3 GPa. The method does not limit the data acquisition speed or the
spatial resolution of the force microscope. It is non-invasive and minimizes the influence of the
tip radius on the measurements. The use of several information channels (first and second
mode) results in the calculation of Young modulus and viscosity coefficients which do not
depend on the applied force. The results coincide with the results obtained by other wellestablished methods (static AFM, force inversion methods).
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Figure: (a) Indentation map in a block copolymer (PS-b-PMMA) thin film (scale bar, 100 nm). (b) Map of the elastic
modulus of PS-b-PMMA (scale bar, 100 nm). (c) Cross-section along the dashed line shown in a. (d) Histogram of the
elastic modulus obtained from b.
[1]. R. Garcia and E.T. Herruzo.Nat. Nanotechnol. 7, 217-226 (2012).
[2]. D. Martinez-Martin, E.T. Herruzo, C. Dietz, J. Gomez-Herrero and R. Garcia. Phys. Rev. Lett. 106, 198101
(2011)
[3]. E. T. Herruzo and R. Garcia. Beilstein J. Nanotechnol. 3, 198–206 (2012)
[4]. E. T. Herruzo, A.P. Perrino and R.Garcia. Nat. Comm. 3, 3126 (2014)
Mechanical uncoating of a virus genome: an AFM-TIRF combined
experiment
A. Ortega-Esteban1*, K. Bodensiek2*, G. Condezo3, M. Suomalainen4, U. Greber4, C. San
Martín3, P. J. De Pablo1, I. A. T. Schaap2
1
Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain
2
Fakultät für Physik, III. Physikalisches Institut, Georg August Universität, Göttingen, Germany
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Department of Macromolecular Structures, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
4
Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
* These authors contributed equally to this work
In the infection pathway of human adenovirus, the icosahedral viral cage suffers a stepwise
disruption starting by losing the vertices (pentons). A partially disrupted particle docks to
nuclear pores releasing the genome inside the cell nucleus. The details of DNA diffusion out of
the virus during this process remain elusive. Previous studies with Atomic Force Microscopy
(AFM) in liquids demonstrated that mechanical disruption of viral cages in a controlled way
recapitulates the stepwise uncoating process occurring in the cell. However DNA diffusion
occurs in a 3D fashion, impairing the study of this process by 2D techniques such as AFM,
which requires the immobilization of biomolecules on surfaces. Therefore, we have designed
and carried out experiments combining Total Internal Reflection Fluorescence Microscopy
(TIRF) and AFM, where both techniques are used in a complementary way to characterize DNA
release from human adenovirus cages. In our studies, we induce the mechanical uncoating of
individual adenovirus particles with AFM and, simultaneously, monitor DNA diffusion with
TIRF. Our preliminary results establish a direct relationship between the compaction of viral
genome and its diffusion outside the viral shell as revealed by TIRF data.
Mechanical Properties Of Antibodies As Measured By AFM: An
Atomistic Molecular Dynamics Study
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J.G. Vilhena , Pedro A. Serena , Ruben Perez
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Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid , Spain Departamento de Física Teórica de
la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain
Antibodies are key elements of the immune system. A better understanding of their
nanomechanical properties could allow exploiting all of their targeting properties. Recent
advances on molecular-dynamics (MD) simulations allow studying such large systems with an
atomistic detail. Furthermore, the newly developed high-resolution multi-frequency atomicforce-microscopy (MF-AFM) provides now information about the nanomechanics of
proteins[1]. Here we have combined both techniques to measure the flexibility map of the IgG
antibody (150kDa), the second most abundant plasma protein that provides the majority of
antibody-based immune response. AFM experiments are modeled performing many (>60)
steered molecular dynamics sampled over long equilibrations (>100ns), thus obtaining large
statistics and small error on the indentation forces. The tip and the supporting substrate for
the IgG adsorption are modeled as a capped carbon nanotube and a three layers slab of
graphite, respectively. Our results[2] address the ultimate spatial resolution and force
sensitivity of MF-AFM on biological samples, as well as the role played by water molecules on
the indentation process.
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R. Garcia et al; PRL 106, 198101 (2011)
Mechanical properties of antibodies: an atomistic MD and MF-AFM study; in preparation.
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Structural Analysis Of Individual Protein Complexes By Infrared
Scattering At An AFM Tip
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Iban Amenabar , Simon Poly , Wiwat Nuansing , Elmar H. Hubrich , Alexander A.
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Govyadinov , Florian Huth , Roman Krutokhvostov , Lianbing Zhang , Mato Knez ,
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Joachim Heberle , Alexander Bittner , Rainer Hillenbrand
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CIC nanoGUNE Consolider, 20018 Donostia - San Sebastián, Spain Neaspec GmbH, 82152 Martinsried,
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Germany Experimental Molecular Biophysics, Department of Physics, Freie Universität Berlin, D-14195
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Berlin, Germany IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain
We introduce the mapping of protein structure with 30 nm lateral resolution and sensitivity to
individual protein complexes by infrared scattering-type scanning near-field optical microscopy
(IR s-SNOM) and Fourier transform infrared nanospectroscopy (nano-FTIR). s-SNOM and nanoFTIR are based on r ecording the infrared light scattered by a metallized atomic force
microscope tip probing the sample surface. We present and discuss local broadband spectra of
individual viruses, ferritin complexes, purple membranes and insulin aggregates, which can be
interpreted in terms of their alpha-helical and/or betasheet structure [1]. Applying nano-FTIR
for studying insulin fibrils - a model system widely used in neurodegenerative disease research
- we find clear evidence that 3-nm-thin amyloid-like fibrils contain a large amount of alphahelical structure. Nano-FTIR spectra of one ferritin complex demonstrate extraordinary
sensitivity to ultra-small amounts of material, about 1 attogram of protein, respectively 5000
C=O bonds. By further sharpening the tips and optimizing their antenna performance, we
envision single protein spectroscopy in the future, paving the way to a new era in infrared biospectroscopy. We foresee manifold applications, such as studies of conformational changes in
amyloid structures on the molecular level, the mapping of nanoscale protein modifications in
biomedical tissue or the label-free mapping of membrane proteins.
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Amenabar I, Poly S, Nuansing W, Hubrich E, Govyadinov A, Huth F, Krutokhvostov R, Zhang L, Knez M, Heberle
J, Bittner A, Hillenbrand R. Structural analysis and mapping of individual protein complexes by infrared
nanospectroscopy. Nature Communications 2013,4:2890
Scattering Properties Of Graphene Nanostructures On Ni(111)
1,2
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A. Garcia-Lekue , T. Balashov , M. Ollé , G. Ceballos , A. Arnau
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D. Sánchez-Portal , A. Mugarza
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, P. Gambardella
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Donostia International Physics Center (DIPC). Donostia-San Sebastian. IKERBASQUE, Basque
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Foundation for Science, Bilbao. Catalan Institute of Nanoscience and Nanotecnology (ICN2), Bellaterra.
4
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Centro de Física de Materiales CFM, Centro Mixto CSIC-UPV, Donostia-San Sebastian. Dpto. de Física
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de Materiales UPV/EHU, Facultad de Química, Donostia-San Sebastian. Institució Catalana de Recerca i
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Estudis Avançats (ICREA), Barcelona. Department of Materials, ETH Zurich, Zurich.
The graphene-metal interaction can be exploited to engineer hybrid structures with novel
electronic and magnetic properties. The graphene-Ni interface is an interesting case where the
interaction with the ferromagnetic substrate opens hybridization gaps and induces magnetic
moments.[1,2] We investigate the electronic properties of graphene nanoislands grown on
Ni(111), [3] using local tunneling spectroscopy measurements combined with spin-polarized ab
initio calculations.[4] We show that the electron scattering at the graphene edges is found to
be spin- and edge-dependent. This behavior is attributed to the strong distortion of the
electronic structure at the interface, which opens a gap and spin-polarizes the Dirac bands of
graphene. We also demonstrate that edge scattering is strongly structure dependent, with
asymmetries in the reflection amplitude of up to 30% for reconstructed and unreconstructed
zig-zag edges.[5] These results suggest a lateral 2D spin filtering for graphene layers, similar to
that occurring
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Figure: (a) Topographic (top) and constant current dI/dV map (bottom) showing the interference pattern of the
surface state scattered from graphene islands. (c) Calculated planar average density of the majority and minority
surface states of Ni(111) at the Г point.
V. M. Karpan et al. Phys. Rev. Lett. 99, 176602 (2007)
M. Weser et al., Appl. Phys. Lett. 96, 012504 (2010)
M. Olle et al. Nano Lett. 12, 4431 (2012).
A. Garcia-Lekue et al., Phys. Rev. Lett. 112, 066802 (2014)
M. Olle et al., to be submitted.
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A. Martín-Recio1, A. J. Martínez-Galera1,2, J. M. Gómez-Ródriguez1
Depto. de Física de la Materia Condensada, Universidad Autónoma de Madrid, Spain;
2
Physikalisches Institut, Universität zu Köln, Zulpicher Str. 77, Köln, Germany
Through all the different graphene growth techniques developed during the last years, the
chemical vapor deposition (CVD) on transition metals has demonstrated to be one of the best
ones producing high quality, large scale graphene films. For this reason, the physics of
graphene-metal interactions has attracted the attention of worldwide research[1]. When the
carbon layer is grown on low reactive metals such as Pt(111)[2], Cu(111) or Au(111)[3], the low
coupling between them leads to several rotational domains of the graphene layer giving rise to
several moiré patterns. On the other hand, if the graphene is grown on Ru(0001)[4] or
Rh(111)[5], there occurs an hybridization of the graphene π and the metallic d bands[1].
Because of this strong coupling, only one moiré pattern was expected. In the case of graphene
on Rh(111), this structure is formed by (12x12) C atoms aligned with (11x11) Rh(111).
In this study we present, for the first time, the growth of multidomain graphene on Rh(111)
under ultra-high vacuum (UHV) conditions by means of STM. Many different unexpected moiré
patterns were observed on this reactive metal surface. These unusual structures,
corresponding to smaller periodicities than the normal (12x12) C moiré, have been modeled
through atomic resolved data by comparison with the larger moiré (figure 1). Also, the
apparent corrugation of all these structures has been studied and its dependence on the moiré
lattice parameter has been analyzed.
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patterns
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Fig. 1. 15 x 15 nm atomically resolved STM image where two different moirés are observed (corresponding models
are shown on the left). The moiré named as “0” is the aligned (12 x 12) C superstructure. The parameters of the new
moiré (1) are shown (VS= 30 mV, IT= 19 nA)
M. Batzill, Surf. Sci. Rep. 67, 83, (2012)
M. M. Ugeda, D. Fernández-Torre, I. Brihuega, P. Pou, A.J. Martínez-Galera, R. Pérez, and J.M. GómezRodríguez, Phys. Rev. Lett. 107, 116803, (2011)
A. J. Martínez-Galera, I. Brihuega, and J. M. Gómez-Rodríguez, Nano Lett. 11, 3576, (2011)
B. Borca, S. Barja, M. Garnica, M. Manniti, A. Politano, J. M. Rodríguez-García, J. J. Hinarejos, D. Farías, A. L.
Vázquez de Parga, R. Miranda, New J. Phys. 12, 093018 (2010)
E. N. Voloshina, Y. S. Dedkov, S. Torbrugge, A. Thissen, M. Fonin, Appl. Phys. Lett. 100, 241606, (2012)
Mechanical Properties Of Graphene With Defects Created By Ion
Bombardment
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Guillermo López-Polín , Cristina Gomez-Navarro , Vincenzo Parente , Francisco
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Guinea , Mikhail I. Katsnelson , Francesc Perez-Murano , Julio Gomez-Herrero
1
1,2
Dpto. de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049, Madrid, Spain.
2
Centro de Investigación de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049,
3
4
Madrid. Instituto de Ciencia de Materiales, CSIC, 28049, Madrid, Spain Radboud University Nijmegen,
5
Institute for Molecules and Materials, Heyendaalseweg 135, NL6525AJ Instituto de Microelectrónica
de Barcelona, CSIC, 08193 Bellaterra, Spain.
Pristine graphene sheets exhibits superior mechanical properties very promising for
applications: they are very light, flexible, stiff, and strong [1]. One of the main problems for its
applications is that the known routes to obtain graphene in large scale (CVD, Graphene oxide),
produce layers with different kind of defects (grain boundaries, point defects). These defects
have been demonstrated to lower the stiffness and strength of the layers [2, 3]. Unfortunately,
the fact that these defects are created in a non-controlled manner during sample preparation
prevents a systematic study of how the mechanical properties vary with the defects. Our
approach in this work is to introduce defects in our membrane in a controlled manner by Ar+
ion bombardment, creating mainly atomic monovacancies. For a precise characterization of
the defect type and density we use Raman spectroscopy and STM. Then we measure the
variation of the stiffness and strength with defect density using AFM nanoindentations (Fig.1).
Counter intuitively, we find that the stiffness of graphene increases with defect content until a
36
vacancy content of ~0.2%, where it doubles its initial value. For higher irradiation doses the
elastic modulus slowly decreases with defects inclusion. The initial increase in stiffness can be
explained in the framework of statistical mechanics of 2D membranes, where the elastic
coefficients are predicted to depend with the momentum of flexural modes [4]. In contrast to
the elastic trend, the fracture strength decreases with defect density according to standard
fracture continuum models.
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C. Lee, X. D. Wei, J. W. Kysar, J. Hone, Science, 321 (2008), 385
C. Gomez-Navarro, M. Burghard, K. Kern, Nano Letters, 8 (2008), 2045
C. S. Ruiz-Vargas et al., Nano Letters, 11 (2011), 2259.
J. A. Aronovitz, T. C. Lubensky, Physical Review Letters, 60 (1988), 2634
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Uniaxial Strain Control of Metal Insulator Transitions in Sr2IrO4 thin
films
L. López-Mir,1,2,* X.Martí,1,3,4 M. Paradinas,2 C.Ocal,2 G.Catalán,1,5 N.Domingo.1,6
1
ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193Bellaterra (Barcelona),
2
Spain. Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193 Bellaterra
3
(Barcelona), Spain. Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic.
4
Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke
5
Karlovu 5, 12116 Praha 2, Czech Republic. ICREA - Institucio Catalana de Recerca i Estudis Avançats,
6
08010 Barcelona, Spain. CSIC - Consejo Superior de Investigaciones Cientificas, ICN2 Building ,08193
Bellaterra (Barcelona), Spain
Recent studies suggest that manipulation of the epitaxial strain can tune the electronic
structure of the Jeff = ½ Mott insulator Sr2IrO4, which is a transition metal oxide that exhibits
an exotic insulating state [1,2]. When thin films are grown on a substrate the mismatch
between the lattice constant of the substrate and lattice constant of the thin film material
induces an in-plane strain in order to achieve epitaxial growing. The in-plane lattice mismatch
between Sr2IrO4 and the substrates can exert tensile or compressive strains to the film. On the
other hand, mechanical stimuli induced by the tip of an atomic force microscopy (AFM) is the
basis for the generation of different types of phenomenologies, from flexoelectric fields that
can lead to mechanical writing in ferroelectric materials [3] to piezochemical effects due to the
dynamics in ionic systems [4].
In this work, we present a novel technique to induce an insulator-to-metal transition by
applying uniaxial pressure to the material through an Atomic Force Microscope (AFM) tip. We
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achieve the reversible mechanical control of dielectric gap in a semiconductor oxide that lead
to metal-insulator transitions induced by uniaxial stress, demonstrating that local electronic
structures can be locally changed by applying uniaxial pressure through an AFM tip. The AFM
tip also acts as a sensor and transport measurements through the AFM tip are done through
different approaches. In all cases the experimental setup consist of the sample and tip placed
in series resulting in a capacitor where the tip is the top electrode and an LSMO thin film
substrate between SIO and STO is the bottom electrode. While the features of the I(V) for the
lowest applied forces resemble those of a semiconductor, linear Ohmic behavior is achieved
for increasing forces with increasing slopes. From the obtained results, we observed a
significant and reversible decrease of the resistance of the Sr2IrO4 thin film as a function of
increasing mechanical loading force on the AFM tip. We attribute this behaviour to an
insulator-to-metal transition caused by pressure induced changes in the Ir-O-Ir bond angle in
the plane which produce a closure of the band gap.
Fig 1. Resistance as a function of the applied forcé through an AFM onto Sr2IrO4
C. Rayan Serrao, et al., Physical Review B 87, (2013) 085121.
J. Nichols, et al.,Appl. Phys. Lett. 102, (2013) 141908.
H. Lu, et al., Science 336, 59 (2012).
Y. Kim, et al.,Nanoletters 13 (2013) 4068.
In Situ High Pressure STM Imaging Of A Fischer-Tropsch Cobalt
Catalyst
1
1
Violeta Navarro , M.A. van Spronsen , J.W.M. Frenken
1
1
Kamerlingh Onnes Laboratory. Leiden University. Leiden, The Netherlands.
Real dynamic systems, for example catalysts, can only be understood when they are examined
under realistic working conditions. Otherwise the physico-chemical processes governing the
system might not be the same. Although catalysts’ have largely been studied with traditional
surface science techniques, those are typically used under vacuum conditions- very different to
the real industrial ones. The difference in pressure, the “pressure gap”, between those vacuum
studies and the industrial ones can be up to 13 orders of magnitude. Even though the studies
in vacuum can be very revealing [1], the “pressure gap” leads to dramatic differences between
laboratory and industrial systems. We need to study catalytic systems in situ since reaction
mechanisms and changes on the catalyst surface during the reaction [2] can be very different
under the fore mentioned pressures. In our lab we follow catalysts at the atomic scale
reproducing the conditions of pressure and temperature used in the industry. We do this using
38
a scanning tunneling microscope (STM) which can work under high pressures (up to 6 bar) and
temperatures (up to 320°C) [2, 3]. The STM tip is inside a small gas flow reactor placed in a
UHV chamber. Traditional surface science techniques are used to prepare and characterize the
samples down to the atomic level, before exposing them to reaction conditions. We can
visualize the structural changes on the surface of the catalyst during the reaction.
Simultaneously we use mass spectrometry to detect the gaseous products of the reaction to
correlate them with structural changes. As a model catalyst, we have used a single crystal of
cobalt to study the Fischer-Tropsch synthesis (FTS). This catalytic reaction produces
hydrocarbons of different lengths from a mixture of CO and H2, like octanes, used as fuel. This
reaction is of extreme industrial relevance but the fundamental mechanisms are still not
known [4]. We have got some insight into the catalyst in action. We have observed several
changes on the very dynamic cobalt surface at the atomic scale during the reaction. Among
others, islands with internal periodicity appear on the surface. We believe that those are
molecules produced during the reaction that self assemble on the surface depending on their
length forming regular arrays and they eventually desorb.
G. Ertl. Angewandte Chemie International Edition, 52, 1, 52–60, (2013). Y.D.Yin, et al., Science, 304, 5671. 711
(2004). R. Schaub, et al.. Phys. Rev. Let. 87, 26 (2001).
B. L.M. Hendriksen, et al., Topics in Catalysis, 36, 1–4 (2005).
C.T. Herbschleb et al. Rev. Sci. Instr. Submitted.
J. Wilson et al., J. Phys. Chem. 99, 7860 (1995).
2
3
1
Elisa Palacios-Lidón , David F. Pickup , Eneko Azaceta , Jaime Colchero , Ramón Tena3
Zaera , Celia Rogero
1
2
2
Centro de Investigación en Optica y Nanofísica, Universidad de Murcia, Murcia, Spain Centro de Física
3
de Materiales (CSIC-UPV/EHU,) San Sebastian, Spain Energy Division, IK4-CIDETEC, San Sebastian, Spain
Dye-sensitized solar cells (DSCs) are seen as promising candidates for the next generation of
inexpensive but efficient solar-energy conversion. During the last decade, ZnO has become an
appealing material for applications in optoelectronic devices due to its unique properties such
as wide band gap, strong room-temperature luminescence; and, most importantly, low cost.
Recently, it has been envisaged as a possible alternative to the wide-band-gap TiO based
2
DSCs. However ZnO DSCs efficiencies (7.5%) are still modest compared to those of TiO2-based
devices (13%) [1,2]
The aim of this work is to study the nanophotoactivity of polycrystalline ZnO samples
functionalized with porphyrin IX (H2PPIX) dye. The electrostatic response of the samples has
been studied in darkness and under illumination using KPM and ESFM. From these
measurements the charge photogeneration and dye-ZnO charge transfer are inferred. Fig.1
shows the electrooptical behavior of the bare and H2PPIX functionalized ZnO samples when
the illumination is performed at the Soret band of the porphirine (λ=400nm).In this work we
will discuss the fact that whilst no significant changes are observed in the morphology the
electrostatic properties drastically change between bare and functionalized surfaces.
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Nanophotoactivity Of Porphyrin Functionalized ZnO Solar Cells
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N. Memarian, I. Concina, A. Braga, S. M. Rozati, A. Vomiero and G. Sberveglierit, Angew. Chem. Int. Ed. 50,
12321 (20011)
S. Mathew, A. Yella, P. Gao1, R. Humphry-Baker, B. F. E. Curchod, N. Ashari-Astani, I. Tavernelli, U.
Rothlisberger, Md. K. Nazeeruddin and Michael Grätzel, Nature Chemistry DOI: 10.1038/NCHEM.1861
(2014)
Study Of Polymer Relaxation Dynamics By Means Of AFM Based
Dielectric Spectroscopy
1,2
2
1
L.A.Miccio , G.A.Schwartz , A.Alegría , J.Colmenero
1
2
1,2,3
3
Universidad del País Vasco. Donostia-San Sebastián. Material Physics Center Donostia International
Physics Center
Polymeric materials present dielectric dispersion and absorption phenomena in the 10-6-1012
Hz range due to the reorientational motion of molecular dipoles and/or the translational
motion of ions/ trapped charges[1]. The systematic study of these phenomena through
broadband dielectric spectroscopy (BDS) reveals information of structure and dynamics of
these materials, therefore having great technological and scientific relevance. A stage has been
reached where the foundations of BDS are well established in terms of a large number of
scientific works for the dielectric behavior of dipolar materials and moderately-conductive
systems[1]. However, in the l ast few years the growing interest in nanostructured materials
highlighted the need of measurements with spatial nanometer resolution, something that is
missing in BDS. In this sense, the use of atomic force microscopy (AFM) as a tool for providing
spatial resolution to the study of dielectric relaxation dynamics appears as the natural
extension of the BDS studies[2-5]. In this work we present a complete characterization of
molecular and collective dipolar fluctuations in polymeric materials by means of AFM based
dielectric spectroscopy. In particular, we focus our analysis in technologically relevant
relaxation processes in different environments i.e., segmental relaxations in immiscible blends
interfaces, polarization processes in nanostructured polymer interfaces, among others. We
propose simple models to quantitatively relate the dielectric losses of the materials with the
detected phase between the electrical excitation and the AFM probe oscillation.
40
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Figure 1. Left: electrical phase image of a PS/PVAc blend (25/75 wt %), acquired at 5 kHz and 350K. Red areas show
the places where the PVAc segmental relaxation takes place with a timescale comparable to the reciprocal of the
excitation frequency, therefore providing the contrast with PS areas (blue). Right: relaxation spectra obtained on
PVAc locations at different temperatures (red dashed line stands for the image excitation frequency).
F. Kremer and A. Schonhals, Broadband Dielectric Spectroscopy (Springer-Verlag, New York, 2003).
P. S. Crider and N. E. Israeloff, Nano Letters 6, 887 (2006).
P. S. Crider, M. R. Majewski, J. Zhang, H. Oukris, and N. E. Israeloff, Applied Physics Letters 91, 013102 (2007).
C. Riedel, R. Arinero, P. Tordjeman, M. Ramonda, G. Lévêque, G. A. Schwartz, D. G. De Oteyza, A. Alegria, and
J. Colmenero, J. Appl. Phys. 106, 024315 (2009).
G. A. Schwartz, C. Riedel, R. Arinero, P. Tordjeman, A. Alegría, and J. Colmenero, Ultramicroscopy 111, 1366
(2011).
A single-molecule approach to study dynamics of DNA helicases by
applying magnetic forces
1
2
2
Carolina Carrasco , Neville Gilhooly , Mark S. Dillingham , and Fernando Moreno1
Herrero .
1
Centro Nacional de Biotecnología, CSIC, Campus UAM, Darwin 3, 28049, Cantoblanco, Madrid, Spain
2
Dept. of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol, BS8
1TD, UK
Single-molecule manipulation and imaging techniques offer high potential to investigate DNA
break repair reactions in new ways, providing information that is inaccessible to conventional
ensemble experiments. Here, Magnetic Tweezers (MT) has been used to follow in real time the
translocation of helicases at the single molecule level. In the MT setup, a single molecule of
DNA is tethered between a streptavidin-coated micrometer-size magnetic bead (SA-bead) and
the bottom glass surface of a liquid cell by Dig-Anti-Dig links. Vertical translation and rotation
of the magnets above the liquid cell induce stretching and torsion forces on the DNA molecule,
respectively. By linking streptavidin-coated paramagnetic beads to biotinylated helicase, we
were able to apply a force against the action of the motor protein and thus monitor the
helicase activity (Fig.1.A). After arrival of ATP, helicase starts to translocate along the DNA
dragging down the microscopic bead to which is attached. The magnetic beads are visualized
using an inverted optical microscope (Fig.1.B) and the bead position (DNA end-to-end
distance) is recorded in real time by video-microscopy. We have studied the processivity and
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translocation rate of a helicase-nuclease protein involved in the DNA repair as a function of the
applied force, DNA sequence, temperature and ATP concentrations on damaged or
undamaged DNA. In the fig.1.C a typical single translocation trace is shown.
XPEEM And LEEM: State Of The Art Surface Characterization Tools At
ALBA
1
Lucia Aballe , Michael Foerster
1
1
ALBA Synchrotron Light Facility, 08290 Cerdanyola del Vallès, Barcelona (Spain)
The ALBA Synchrotron Light Facility (Barcelona) is based on a 3 GeV, low-emittance storage
ring which feeds intense photon beams to different beamlines dedicated to basic and applied
research in many fields, e.g. condensed matter physics, material science, chemistry, biology
and medical sciences.
Among the instruments accessible to external users there is a combined X-ray PhotoEmission
Electron Microscope (XPEEM) and Low Energy Electron Microscope (LEEM), in operation since
2012.
The XPEEM is fed by the variable polarization CIRCE undulator beamline (100-2000 eV photon
energy), and permits imaging surfaces with chemical, structural, and magnetic sensitivity down
to a lateral spatial resolution of 20 nm. XPEEM has applications in a wide variety of fields such
as surfaces and interfaces, nanostructures, or micro-magnetism. Contrast mechanisms based
on x-ray absorption (including dichroism) as well as on photoemission are available, thanks to
an imaging electron energy analyzer with resolution below 0.2eV. Microspot-diffraction (LEED
and photoelectron diffraction) and numerous in situ preparation facilities (evaporators, high
temperature annealing, gas dosage, sputter gun,…) are available in the same instrument,
42
making it a true multitechnique station for the surface characterization of heterogeneous
systems.
An overivew of the XPEEM-LEEM experimental capabilities and application examples will be
presented.
Nanoscale IR Spectroscopy, Dielectric Function Mapping And Depth
Profiling With Near-field Microscopy
1
1
2
1,4
Alexander Govyadinov , Stefan Mastel , Federico Golmar , Andrey Chuvilin , P. Scott
3
Carney , Rainer Hillenbrand
1
1,4
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2
CIC Nanogune Consolider, Donostia-San Sebastian, Spain I.N.T.I.-CONICET and ECyT-UNSAM, San
3
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Martin, Argentina ECE Dept. and Beckman Institute, U. of Illinois atUrbana-Champaign, Urbana, USA
4
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IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
U
Scattering-type scanning near-field optical microscopy (s-SNOM) is a powerful optical
technique for nondestructive spectroscopic imaging with deep subwavelength resolution [1].
s-SNOM is typically based on the atomic force microscopy (AFM), in which the scanning probe
is illuminated externally and the backscattering is detected. The sharp probe concentrates light
at its apex, thus serving as a strong nanoscopic illumination source for the sample. The light
scattered by the probe depends on the local sample composition, therefore providing means
for its investigations at the nanoscale.
S
By employing broadband infrared (IR) illumination source, s-SNOM has demonstrated the
capability of performing nanoscale FTIR spectroscopy of samples (nano-FTIR) [2]. We have
further shown that for weak molecular oscillators (i.e. polymers, biological matter, etc.), nanoFTIR spectra can be directly compared to the far-field FTIR databases, allowing for the chemical
identification of sample components with unprecedented spatial resolution [3].
In this work we demonstrate the ability of IR s-SNOM and nano-FTIR to quantitatively measure
local dielectric function of thin films samples composed of weak oscillators [4]. Our approach is
based on a theoretical description of s-SNOM scattering process that allows for an analytic
inversion of s-SNOM data, i.e. analytically solves the near-field scattering problem to obtain
the solution for the dielectric permittivity. Such inversion does not require fitting or
minimization procedures, thus providing high speed and robust performance. It yields the
same information about the sample as typically obtained by far-field ellipsometry with an
important advantage of providing nanoscale spatial resolution even at IR frequencies.
We further show that simultaneously with the dielectric permittivity, the film thickness can be
recovered from s-SNOM data without relying on measurements of topography [5]. In other
words, our work enables the quantitative nanoscale-resolved in-depth profiling of dielectric
properties of heterogeneous samples in which the topography does not correlate with the
chemical or optical properties. It presents an important advance towards complete threedimensional near-field tomography and opens new frontiers for chemometrics, materials and
bio sciences.
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T. Taubner, R. Hillenbrand, and F. Keilmann, Appl. Phys. Lett. 85, 5064 (2004)
F. Huth, M. Schnell, J. Wittborn et al, Nat. Mater. 10, 352 (2011)
F. Huth, A. Govyadinov, S. Amarie et al, Nano Lett. 12, 3973 (2012)
A. Govyadinov, I. Amenabar, F. Huth et al, J. Phys. Chem. Lett. 4, 1562 (2013)
A. Govyadinov, S. Mastel, F. Golmar et al, submitted to ACS Nano
44
A step further for better understanding of molecular junctions and
highresolution SPM images
P. Jelinek
Institute of Physics of the AS CR, Prague, Czech Republic
The recent progress in Scanning Probe Microscopy provided unprecedented atomic resolution
of single molecules [1,2]. What more, simultaneous AFM/STM measurements allow precise
control of both mechanical and transport properties on single molecular junctions [3]. In first
part of the talk, I will a simple mechanistic model of STM/AFM imaging mechanism of organic
molecules with functionalized probe, which takes into account relaxation of the molecular
probe due to tip-sample interaction. We will demonstrate, that the model is able to produce
very well not only experimentally observed intra and intermolecular contrast but also its
evolution upon the tip approach, comparing directly theoretical and experimental AFM/STM
images of PTCDA on Au(111). In second part, I will discuss bias dependent simultaneous ncAFM/STM measurements on single molecular junction, which reveals presence of current
driven force acting in molecular junction. I will also discuss the theoretical understanding of
these measurements.
L. Gross et al., Science 325,1110 (2009)
C. Weiss et al., Phys.Rev.Lett. 105, 086103 (2010)
N. Fournier et al Phys. Rev. B84, 035435 (2011).
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1
Dimas G. de Oteyza , Yenchia Chen , Ting Cao , Chen Chen , Zahra Pedramrazi ,
1
1,2
1,2
Danny Haberer , Felix R. Fischer , Steven G. Louie , Michael F. Crommie
1
1,2
University of California at Berkeley, Berkeley, USA 2 Lawrence Berkeley National Laboratory,
Berkeley,USA 3 Centro de Fisica de Materiales CSIC-UPV/EHU, San Sebastian, Spain
A prerequisite for future graphene nanoribbon (GNR) applications is the ability to finetune the
electronic band gap of GNRs. Such control requires the development of fabrication tools
capable of precisely controlling width and edge geometry of GNRs at the atomic scale. With
the advent of bottom-up synthesized GNRs increasingly high hopes are being placed on this
approach and the resultant atomically precise GNRs. We report a controlled GNR band gap
modification via covalent self-assembly of different species of molecular precursors that yield
n = 13 and n = 7 armchair GNRs (where n stands for the number of C dimer lines across the
ribbon width)[1]. Scanning tunneling microscopy and spectroscopy (STM & STS) reveal that n =
13 armchair GNRs have a band gap of 1.4 eV, 1.2 eV smaller than the gap determined for n = 7
armchair GNRs. It is predicted that further GNR bandgap engineering may be realized utilizing
combinations of two or more different building blocks that vary width or doping at desired
positions (in analogy to the well-established bandgap engineering in inorganic materials)[2].
We apply this same concept combining both types of precursors, demonstrating bottom-up
Friday, August 29, 2014, San Sebastián, Spain
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Bandgap Engineering Of Bottom-Up Synthesized Graphene
Nanoribbons
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synthesis of width modulated GNRs. We study the resultant junctions with STM and STS, and
identify distinct electronic structures in individual GNR segments. We have additionally
performed first-principles calculations that further support our experimental results.
Y.-C. Chen, D. G. de Oteyza, Z. Pedramrazi, C. Chen, F. R. Fischer, M. F. Crommie, ACS Nano 2013, 7, 6123
H. Sevinçli, M. Topsakal, S. Ciraci, Phys. Rev. B 2008, 78, 245402
General Force Reconstruction Method for Amplitude Modulation Force
Microscopy Experiment
A.F. Payam, D. Martin-Jimenez , R. Garcia
E-mail: [email protected]
Amplitude Modulation Atomic Force Microscopy (AM-AFM) is the most widely used technique
for nanoscale characterization of materials and surfaces in the air and liquid environments.
High detection or sensitivities and smaller lateral forces with respect to contact AFM are the
advantages of the dynamic modes of AFM. However, in AM-AFM experiments the interaction
force is not direct observable [1].
Several methods have been proposed to recover the force in AM-AFM with the use of a unique
frequency of excitation. These methods are valid either for small or large amplitudes relative
to the indentation length [2]-[4]; or expand the force in terms of polynomials which require
determination of a large number of parameters which makes them complicated for practical
implementation [2], [5]. To overcome the above limitations, we develop a general method to
transform the observables in amplitude modulation force microscopy into quantitative force
measurements. The force reconstruction algorithm has been deduced on the assumption that
the observables (amplitude and phase shift) are slowly varying functions of the average tipsurface distance. This method is general because is valid for small and large amplitudes;
operation in air and liquid, compliant and rigid materials, conservative and non-conservative
interactions alike. Numerical analysis and experimental tests verify the accuracy and validity of
the proposed method.
(a) AFM image of polystyrene (PS) and polyolefin elastomer (LDPE) blend. (b) Amplitude and phase shift versus zpiezo displacement on PS corresponding to black cross in a. (c) Force reconstruction of PS. (d) Amplitude and phase
shift versus z-piezo displacement on LDPE corresponding to white cross in a. (e) Force reconstruction of LDPE.
46
[1].
[2].
[3].
[4].
[5].
D. Platz, D. Forchheimer, E.A. Tholén and D.B. Haviland, Nat. Comm. 4, 1360 (2013).
M. Lee and W. Jhe, Phys. Rev. Lett. 97, 036104 (2006).
H. Holscher, U.D. Schwarz, int. J. Nonlinear Mech. 42, 608-625 (2007).
A.J. Katan, M.H. van Es and T.H. Oosterkamp, Nanotech. 20, 165703 (2009).
S. Hu and A. Raman, Nanotech. 19, 375704 (2008).
Adsorption Geometry Of Pentacene On TiO2 Anatase Surface Resolved
By Intra-molecular Atomic Force Microscopy Imaging
1
1
2
1
Cesar Moreno , Oleksandr Stetsovych , Milica Todorovic , Tomoko K. Shimizu , Rubén
2
Pérez , Oscar Custance
1
1
National Institute for Materials Science (NIMS), 1-2-1 Sengen Tsukuba, Ibaraki 3050047, Japan 2
Departamento de Física Teórica de la Materia Condensada, Universidad Autonoma de Madrid, E-28049
Madrid (Spain)
TiO2 is very promising material because it is stable, non-corrosive, environmentally friendly,
abundant and cost- effective. Since most of the peculiar properties of TiO2 are surfacemediated, a deep understanding of the surface properties of this reducible oxide material is a
critical issue to develop high-performance devices. Furthermore, pentacene is an archetypical
organic small molecule broadly used in organic electronics devices. Here, we present a
characterization of the morphology and electronic properties of this molecule deposited at
submonolayer regime on the TiO2(101) anatase surface by combining Kelvin Probe Force
Microscopy and simultaneous atomic force microscopy / scanning tunneling microscopy
working with atomic resolution. Intra-molecular structure of planar pentacene was successfully
achieved (Figure 1) simultaneously with the atomic resolution of the titanium dioxide surface,
allowing us to put insight in the adsorption geometry (shape, size and relative position) of
pentacene on TiO2 surface with atomic accuracy. These experimental results have been
corroborated by first-principles calculations.
Figure 1
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Attractive Tip-sample Force Reconstruction For Dynamic Atomic Force
Microscopy In Ambient Conditions
1
1
2
2
Albert Verdaguer , Annalisa Calo , Carlo Alberto Amadei , Matteo Chiesa , Sergio
3
Santos
1
2
Institut Català de Nanociencia i Nanotecnologia (ICN2), Bellaterra (Barcelona), Spain Masdar Institute
3
of Science and Technology, Abu Dhabi, United Arab Emirates Departament de Disseny i Programació
de Sistemes Electrònics, UPC - Universitat Politècnica de Catalunya, Manresa (Barcelona), Spain
Since its advent and due its high spatial resolution, Atomic Force Micorscopy (AFM) has
enabled probing single nanostructures, mapping heterogeneous compositional variation in
surface properties or studying molecular interactions. Initially the AFM was developed to
operate in the quasistatic or DC mode but dynamic modes of operation where introduced to
reduce lateral forces while imaging and enhance versatility. In terms of nanoscale processes
and properties, a main advantage of dynamic AFM modes over DC modes relates to their
capacity to simultaneously probe both conservative and dissipative forces while tracking the
topography for imaging. Conservative and dissipative forces provide mechanical and chemical
information about samples at the nanometer scale. Force reconstruction maps in DC modes,
i.e. quasistatic modes, suffer from stability resulting in so-called "jump-to-contact" where
information for a range of distances is lost. Also the signal-to-noise ratio might be
compromised by pink noise, i.e. noise is proportional to the inverse of the frequency. On the
other hand, interpreting data acquired from the dynamic modes of operation requires detailed
modeling and care as the tip follows a non-monotonic force trajectory during each oscillation
cycle. We have applied a mathematical model to reconstruct, from simple amplitude and
phase versus distance curves, the interaction forces between the AFM tip and a sample in
ambient conditions [1]. We will show our results on the reconstruction of forces acting before
mechanical contact between the tip and the sample occurs. That would include capillary forces
[2], long-range van der Waals forces and forces arising from the formation of chemical bonds.
Figure a) Scheme of the possible interactions occurring between an AFM tip and a surface. b) Experimental
reconstruction of the force (Fts) from amplitude (A) and phase variation as a function of tip-sample separation in
dynamic AFM.
S. Santos, C. A. Amadei, A. Verdaguer, M. Chiesa. J. Phys. Chem. C 117 - 20, 10615 –10622 (2013)
C. A. Amadei, S. Santos, S. O. Pehkonen, A. Verdaguer, M. Chiesa. J. Phys. Chem. C. 117 - 40,20819 –20815
48
(2013)
Atomic Force Microscopy In High Vacuum: Experiments On Graphitic
Surfaces
1
2
3
2
M. Jaafar , G. López Polin , D. Martínez Martín , C. Gómez Navarro , J. Gómez Herrero
1
2
Instituto de Ciencia de Materiales de Madrid, ICMM- CSIC. Madrid, Spain 2 Departamento de Física de
la Materia Condensada, Univerisdad Autónoma de Madrid, Madrid, Spain 3 Department of Biosystems
Science and Engineering ETH, Zurich, Basel,Switzerland
Atomic Force Microscopy (AFM) working in high vacuum (HV) conditions is a valuable
technique due to its sensitivity and versatility. In this work we present different experiments in
carbon-based materials. We use the HV-AFM to perform different experiments on graphitic
surfaces like graphene and graphene oxide (GO). Graphene can be described as one-atom thick
layer of graphite. For many applications, the interaction of graphene and GO with the
supporting substrate and with adjacent layers plays a relevant role in properties such as
adhesion, charge transfer [1], doping level etc. Furthermore, it is important to take into
account the presence of atmospheric contaminants for a correct interpretation of
experimental data [2]. Finally, we have studied the influence of a pressure difference onto the
mechanical properties of suspended graphene membranes [3]. We have studied the diffusion
through these membranes as a function of the kinetic diameter of the gas molecules [4]
(Figure 1).
F
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Figure 1. Suspended monolayer of graphene as a selective gas barrier.
M. Jaafar et al. Appl. Phys. Lett. 101, 263109 (2012)
D. Martinez-Martin, et al. Carbon 61 33 –39 (2013)
G. López – Polín et al. submitted
M.Jaafar et al. in preparation.
49
ABSTRACTS. POSTER PRESENTATIONS
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List of Posters
P1 ...................................................................................................................................................................................................... 57
Graphene Growth On Pt(111) And Au(111) Using A MBE Solid Carbon Source ........................................................................ 57
Irene Hernández-Rodríguez, J. M. García, J. A. Martín-Gago, P. L. de Andrés, Javier Méndez ................................................ 57
P2 ...................................................................................................................................................................................................... 58
Quantum Interference In Tunneling Through A Molecular Kondo System .................................................................................. 58
I. Fernandez-Torrente, M. Ruby, T. R. Umbach, B. W. Heinrich, J. I. Pascual, K. J. Franke ...................................................... 58
P3 ...................................................................................................................................................................................................... 59
Mechanical Force Modulates the Unfolding Pathways of the Cold-Shock Protein B from Thermotoga Maritima ....................... 59
Jörg Schönfelder, Raul Perez-Jimenez, Victor Muñoz ................................................................................................................ 59
P4 ...................................................................................................................................................................................................... 60
Replication Initiation Proteins Studied With Atomic Force Microscopy........................................................................................ 60
Maria Eugenia Fuentes-Perez, Katarzyna Wegrzyn, Igor Konieczny, Fernando Moreno-Herrero .............................................. 60
P5 ...................................................................................................................................................................................................... 61
Design an Iterative Learning Observer to Reconstruct the Interaction Force in AM-AFM ........................................................... 61
F. Payam, D. Martin-Jimenez, R. Garcia ..................................................................................................................................... 61
P6 ...................................................................................................................................................................................................... 61
STM And Nc-AFM Investigation Of Submonolayer Copper Oxide Structures ............................................................................. 61
Carmen Ocal, Esther Barrena, Sonia Matencio ........................................................................................................................... 61
P7 ...................................................................................................................................................................................................... 62
Structural Control Of Bridge State Resonances In Single Molecular Junctions .......................................................................... 62
Carly Brooke, Andrea Vezzoli, Simon J. Higgins, Linda A. Zotti, Juan Jose Palacios, Richard J. Nichols ................................. 62
P8 ...................................................................................................................................................................................................... 63
Magnetic Force Microscopy Of Focused Ion Beam Patterned Co Antidot Arrays ....................................................................... 63
Andreas Kaidatzis, Rafael Pérez del Real, Raquel Alvaro, Jose V. Anguita, Manuel Vazquez, José Miguel García-Martín ..... 63
P9 ...................................................................................................................................................................................................... 64
Investigating Subsurface Boron Dopants In Si(111)-(√3x√3) R30° Using Simultaneous Nc-AFM/STM And DFT..................... 64
Jan Berger, Evan J. Spadafora, Pingo Mutombo, Mykola Telychko, Martin Ondráček, Martin Švec, Alastair McLean, Pavel
Jelínek .......................................................................................................................................................................................... 64
P10 .................................................................................................................................................................................................... 65
Probing The Fermi Surfaces Of The Two-band Superconductor Lead ....................................................................................... 65
B. W. Heinrich, M. Ruby, J. I. Pascual, K. J. Franke.................................................................................................................... 65
P11 .................................................................................................................................................................................................... 66
Boron- and Nitrogen-doped Multiwall Carbon Nanotubes Studied By Kelvin Probe Microscopy ................................................ 66
J. F. González-Martínez, J. Abad, J.-S. Park, J.-M. Lee, S.-O. Kim, J.-S. Kim, A. Urbina and J. Colchero ................................ 66
P12 .................................................................................................................................................................................................... 67
Calibration of Normal Force using non-destructive Dynamic Force Microscopy ......................................................................... 67
Juan Francisco González Martínez, Jaime Colchero Paetz ........................................................................................................ 67
P13 .................................................................................................................................................................................................... 68
52
Modelling dissipation in Dynamic Scanning Force Microscopy as a function of tip-sample distance.......................................... 68
Juan Francisco González Martínez, Jaime Colchero Paetz ........................................................................................................ 68
P14 .................................................................................................................................................................................................... 69
Structure–performance Relationships In Solution-processed Organic Solar Cells Based On Acceptor-substituted S,N
Heteroacenes ............................................................................................................................................................................... 69
Marta Urdanpilleta, Hannelore Kast, Amaresh Mishra, Gisela L. Schulz, Elena Mena-Osteritz, Peter Baeuerle ....................... 69
P15 .................................................................................................................................................................................................... 70
Ether Groups And Acyl-chain Branching Reduce Nanomechanical Resistance Of Phospholipid Bilayers: A Force Spectroscopy
Study ............................................................................................................................................................................................ 70
Aritz B. García-Arribas, Jesús Sot, Daniel Balleza, Kepa Ruiz-Mirazo, Alicia Alonso, Félix M. Goñi ......................................... 70
P16 .................................................................................................................................................................................................... 71
Understanding Transverse Shear Microscopy In Crystalline Organic Layers ............................................................................. 71
A. Pérez-Rodríguez, A. Fernández, C. Ocal, E. Barrena............................................................................................................. 71
P17 .................................................................................................................................................................................................... 72
α-Fe2O3(0001) Surface As A Model Catalyst: Morphology And Electronic Structure ................................................................ 72
Sara Barja, Alexander Weber-Bargioni, Miquel Salmerón ........................................................................................................... 72
P18 .................................................................................................................................................................................................... 73
Surface Charge Differentiation of Avidin and Streptavidin By AFM-Force Spectroscopy ........................................................... 73
L. Almonte, E. López-Elvira, A.M. Baró ....................................................................................................................................... 73
P19 .................................................................................................................................................................................................... 74
Amplitude modulation dynamic force microscopy for stable imaging of samples with heterogeneus in liquids .......................... 74
Lisa Almonte, Arturo M. Baró, Jaime Colchero ............................................................................................................................ 74
P20 .................................................................................................................................................................................................... 75
Detecting charging effects in single molecules by nc-AFM.......................................................................................................... 75
Fabian Schulz, Christian Lotze, Martina Corso, Isabel Fernandez-Torrente, Katharina J. Franke, J. Ignacio Pascual ............. 75
P21 .................................................................................................................................................................................................... 76
Two Dimensional Gadolinium Alloys On Noble Metal Surfaces .................................................................................................. 76
Alexander Correa, Bin Xu, Matthieu Verstraete, Lucia Vitali ....................................................................................................... 76
P22 .................................................................................................................................................................................................... 77
Elastic-Plastic Switch Of Tomato Bushy Stunt Virus Particles .................................................................................................... 77
A. Llauró, E. Coppari, F. Imperatori, A.R. Bizzarri, L. Santi, S. Cannistraro, P. J. de Pablo ....................................................... 77
P23 .................................................................................................................................................................................................... 77
Studying The Mechanical Behavior Of Cardiac Stem Cells By Means Of Atomic Force Microscope ......................................... 77
R. Daza, N. Marí, G. R. Plaza, B. G. Gálvez, A. Bernal, G. V. Guinea, J. Pérez-Rigueiro, M. Elices ......................................... 77
P24 .................................................................................................................................................................................................... 78
Exploring Van Der Waals Interaction For Organic Macromolecules On Metal Surfaces ............................................................. 78
Ane Sarasola, Mikel Abadía, Rubén González -Moreno, Celia Rogero, Aran Garcia-Lekue ...................................................... 78
P25 .................................................................................................................................................................................................... 79
Moirés on Graphene/Pt(111): low temperature NCAFM measurements and first-principles calculations................................... 79
M. Ellner, B. de la Torre, P. Pou, N. Nicoara, J. M. Gómez-Rodríguez, R. Pérez ....................................................................... 79
53
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P26 .................................................................................................................................................................................................... 80
Magnetic Domain Structures In Single Modulated FeCoCu Nanowires ...................................................................................... 80
O. Iglesias-Freire, E. Berganza, C. Bran, M. Vazquez, A. Asenjo ............................................................................................... 80
P27 .................................................................................................................................................................................................... 81
Donor-acceptor Interactions At Solid Surfaces Controlled By Charge Transfer .......................................................................... 81
Koen Lauwaet, J. Rodríguez-Fernández, R. García, M. A. Herranz, N. Martín, J. M. Gallego, R. Otero, R. Miranda ................ 81
P28 .................................................................................................................................................................................................... 82
Local Electrical Properties Of Double Terminated La0.7Sr0.3MnO3 Films ................................................................................. 82
Laura López-Mir, José Cisneros, Carmen Ocal, Lluís Balcells, Benjamín Martínez, Laura López-Mir ....................................... 82
P29 .................................................................................................................................................................................................... 82
The Mode Of Growth And Magnetic Properties Of Ultrathin Co Films Grown On The Curved Pd(111) And Curved Ni(111) .... 82
A. Magaña, M. Ilyn, L. Fernández, J. E. Ortega, F. Schiller ........................................................................................................ 82
P30 .................................................................................................................................................................................................... 83
Neural Signatures Protocol In Artificial Neural Networks Used To Characterize The Electrostatic Signal In Conductive Thin
Films ............................................................................................................................................................................................. 83
Elena Castellano-Hernández, Juan José Sáenz Gutiérrez, Sacha Gómez................................................................................. 83
P31 .................................................................................................................................................................................................... 84
Towards An AFM Study Of The Interaction Of Pseudomonas Aeruginosa With Multivalent Glycoclusters ................................ 84
F. Zuttion, D. Sicard, C. Ligeour, Y. Chevolot, F. Morvan, A. Imberty, G. Vergoten, S. Vidal, J.J. Vasseur, E. Souteyrand, M.
Phaner-Goutorbe ......................................................................................................................................................................... 84
P32 .................................................................................................................................................................................................... 85
Surface Characterization Of PEGylated Self-assembled Monolayers On Gold For Biosensors Applications ............................ 85
A. Garnier, F. Zuttion, F. Palazon, Y. Chevolot, E. Laurenceau, G. Grenet, C. Botella, E. Souteyrand, M. Phaner-Goutorbe .. 85
P33 .................................................................................................................................................................................................... 86
Sublattice localized electronic states in atomically resolved graphene-Pt(111) edge-boundaries .............................................. 86
P. Merino, L. Rodrigo, A. L. Pinardi, J. Méndez, M. F. López, P. Pou, R. Pérez, J. A. Martín-Gago .......................................... 86
P34 .................................................................................................................................................................................................... 87
Quantum Capacitance and Electromigration: A Theoretical Approach ....................................................................................... 87
C. Salgado, J.J. Palacios ............................................................................................................................................................. 87
P35 .................................................................................................................................................................................................... 88
Domain overlap in Ni/Cu/Ni films with perpendicular magnetization: role of defects and ferromagnetic coupling ...................... 88
Miguel Ciria, Edna Corredor, David Coffey, José Luis Diez-Ferrez and José Ignacio Arnaudas ............................................... 88
P36 .................................................................................................................................................................................................... 89
Characterization Of Trimethylamonium-based Ionic Liquid Surfaces With Scanning Force Microscopy .................................... 89
Jaime Colchero, Jesús Sánchez-Lacasa, Pedro Lozano, Juana M. Bernal ................................................................................ 89
P37 .................................................................................................................................................................................................... 90
Manipulation Of The Electronic Structure In A Ruthenium Complex By An STM/AFM Tip ......................................................... 90
Marten Piantek, David Serrate, Jose Ignacio Pascual, Ricardo Ibarra ........................................................................................ 90
P38 .................................................................................................................................................................................................... 90
Temperature Controlled Formation Of Metal-organic Assemblies On Surfaces.......................................................................... 90
54
Marten Piantek, David Serrate, Jose Ignacio Pascual, Ricardo Ibarra ........................................................................................ 90
P39 .................................................................................................................................................................................................... 91
The Verge Of Antiferromagnetic RKKY Order Among Individual Kondo Impurities .................................................................... 91
María Moro-Lagares, Marten Piantek, M. Ricardo Ibarra, José I. Pascual, David Serrate .......................................................... 91
P40 .................................................................................................................................................................................................... 92
Substrate/nanodot Exchange Coupling For Co Nanodot Arrays Grown On Rare Earth–Au (111) Based Nanotemplates ......... 92
L. Fernández, M. Blanco-Rey, M. Ilyn, L. Vitali, A. Magaña, A. Correa, P. Ohresser, J.E. Ortega, A. Ayuela, F. Schiller.......... 92
P41 .................................................................................................................................................................................................... 92
Ultra High Vacuum PVD Graphene growth on Cu-foils from a C60 carbon source: growth and characterization ....................... 92
J.Azpeitia, G. Otero-Irureta, F. J. Mompeán, B. Sánchez, M.García-Hernández, J. A. Martín-Gago, C. Munuera, M. F. López 92
P42 .................................................................................................................................................................................................... 93
Unusual Surface Faceting Induce by Metal Organic Complexes ................................................................................................ 93
M. Abadia, R. González-Moreno, A. Sarasola, G. Otero, A. Verdini, L. Floreano, A. Garcia-Lekue, and C. Rogero ................ 93
P43 .................................................................................................................................................................................................... 94
Search For A Gap-less Dangling Bond Wire. .............................................................................................................................. 94
Mads Engelund, Daniel Sanchez-Portál, Thomas Frederiksen, Aran Garcia-Lekué ................................................................... 94
P44 .................................................................................................................................................................................................... 95
On-surface chemistry: cyclodehydrogenation of PAH catalyzed by metal surfaces. ................................................................... 95
I. Palacio, A.L. Pinardi, G. Otero-Irurueta, J.I. Martinez, M.F. López, J. Méndez, J.A. Martín-Gago ........................................ 95
P45 .................................................................................................................................................................................................... 96
Substrate-Induced Stabilization And Reconstruction Of Zigzag Edges In Graphene Nanoislands On Ni(111) .......................... 96
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M. Olle, A. García-Lekue, D. Sánchez-Portal, J.J. Palacios, A. Mugarza, G. Ceballos, P. Gambardella ................................... 96
E
P46 .................................................................................................................................................................................................... 97
R
Adsorption site dependence of vibrational excitations of molecular hydrogen ............................................................................ 97
E.Carbonell, M. Corso, J. Li, M. Borinaga, J.I. Pascual ............................................................................................................... 97
P47 .................................................................................................................................................................................................... 98
2D To 1D Transition Of Surface States Investigated On Bismuth Curved Crystals .................................................................... 98
Jorge Lobo-Checa, Federico Mazzola, Luca Barreto, Frederik M. Schiller, Justin W. Wells, Nicholas C. Plumb, Johan Adell5,
Philip Hofmann, J. Enrique Ortega............................................................................................................................................... 98
P48 .................................................................................................................................................................................................. 100
A Toolbox For Controlling Quantum States In Organic Monolayers .......................................................................................... 100
Bernhard Kretz, David A. Egger, Egbert Zojer ........................................................................................................................... 100
P49 .................................................................................................................................................................................................. 100
Cementing Proteins Provide Extra Mechanical Stabilization To Viral Cages ............................................................................ 100
M. Hernando-Pérez, S. Kruse, E. Nakatani, C. E. Catalano, P.J. de Pablo1 ............................................................................. 100
P50 .................................................................................................................................................................................................. 101
Doping Of The Surface Of A Topological Insulator With Co Adatoms....................................................................................... 101
M.C.Martínez-Velarte, M. Moro-Lagares, Trevor M. Riedemann, Thomas A. Lograsso, L. Morellón, M.R. Ibarra, D. Serrate. 101
P51 .................................................................................................................................................................................................. 102
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Probing the magnetic interaction between single Cr atoms ....................................................................................................... 102
Zsolt Majzik, José Ignacio Pascual ............................................................................................................................................ 102
P52 .................................................................................................................................................................................................. 103
Are Textbooks Always Right? An AFM Search For Protein Packing Defects In Viruses........................................................... 103
Aitziber Eleta-Lopez, Alba Centeno, Amaia Pesquera, Amaia Zurutuza, Christina Wege, Alexander M. Bittner ..................... 103
P53 .................................................................................................................................................................................................. 104
A Theoretical DFT Study Of Unusual Moiré Patterns In The Graphene/Rh(111) System ......................................................... 104
Ana Martín-Recio, Antonio J.Martínez-Galera, José María Gómez-Rodríguez, Carlos Romero-Muñiz, Pablo Pou, Rubén Pérez
................................................................................................................................................................................................... 104
P54 .................................................................................................................................................................................................. 105
DFT study of AFM metal oxide imaging modes: Towards atomic species identification ........................................................... 105
Diego R. Hermoso, Milica Todorović, Harry Mönig and Rubén Pérez....................................................................................... 105
P55 .................................................................................................................................................................................................. 106
Curved Crystals: A different approach to Surface Science ........................................................................................................ 106
J. E. Ortega, R. González-Moreno, F. López-Geijo, Z. M. Abd-el-Fattah, J. Lobo-Checa, M. Corso, U. Aseguinolaza, A.
Mugarza, A. L. Walter, A. Magaña, M. Ilyin, L.A. Miccio, M. Abadía, and F. Schiller ................................................................ 106
P56 .................................................................................................................................................................................................. 107
Characterization Of Mn0.006NbSe2 From Bulk To Few Layers ................................................................................................ 107
Alexandre Correa orellana, Carmen Munuera, Roberto Fabián Luccas, Mar García Hernández, Hermann Suderow, Federico
Mompean ................................................................................................................................................................................... 107
P57 .................................................................................................................................................................................................. 107
A digital electronics for fast SPM ............................................................................................................................................... 107
I. Horcas, A. Gimeno, P. Ares, J. Gómez-Herrero ..................................................................................................................... 107
56
P1
Graphene Growth On Pt(111) And Au(111) Using A MBE Solid
Carbon Source
1
2
1
1
Irene Hernández-Rodríguez , J. M. García , J. A. Martín-Gago , P. L. de Andrés , Javier
1
Méndez
1
2
Instituto de Ciencia de Materiales de Madrid (CSIC), 28049, Madrid, Spain MBE Lab, Instituto de
Microelectronica de Madrid (CSIC), 28760 Madrid, Spain
Graphene is considered a prototype material with interesting technological applications and
properties [1]. Preparation methods greatly varies from exfoliation mechanical transfer [2]
(widely used in research laboratories), to Chemical Vapor Deposition (CVD) [3] (more
appropriate for industrial applications). When this later method is used, the catalytic
properties of the metallic substrate play a fundamental role during decomposition (cracking of
C-H bonds) of hydrocarbons.
In this work, we present a Molecular Beam Epitaxy (MBE) method to obtain graphene [4] on Pt
(111). This procedure uses evaporation of carbon atoms from a carbon solid-source in ultrahigh vacuum conditions. We have tested the formation of graphene on several surfaces: from
a well establish substrate as platinum, to substrates where graphene can be formed using
innovative methods as gold [5]. For the characterization of the graphene layers we have used
several in situ surface science techniques as low energy electron diffraction (LEED), auger
electron spectroscopy (AES) and scanning tunneling microscopy (STM).
The successful evaporation of carbon has been probed on different substrates as platinum,
HOPG, and gold. By annealing a Pt(111) and Au(111) surfaces up to 600ºC and 450ºC
respectively during carbon evaporation, we have observed a characteristic LEED diagram
attributed to graphene [6]. STM images (see figure) display long range ordering of carbon
monolayers showing several moirés patterns characteristic of graphene on Pt(111) [7] and
islands of dendrites of Au(111) [8], further proving the formation of graphene. This method
opens up new possibilities for the formation of graphene on many different substrates with
potential technological applications.
Figure 1: STM image of graphene on Pt(111) showing
long range moirés patterns and atomic resolution (Bias
Voltage = -35.7mV, Current set-point = 0.04nA).
Figure 2: STM image of graphene on Au(111) showing
long dendritic islands at both sides of the steps. For this
tip-state, graphene appears as a depression area (Bias
Voltage = -12141.7mV, Current set-point = 4μA).
Castro Neto, A.H. et al., Rev. Mod. Phys., 81 (2009) 109.
Geim, A.K. and Novoselov, K.S. Nature Mater., 6 (2007) 183.
57
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Kim, K.S, et al., Nature, 457 (2009) 706-710.
Garcia, J.M. et al., Solid State Commun. 152 (2012) 975-978.
Martinez-Galera, A.J. et al., Nano Lett., 11 (2011) 3576.
Sutter, P. et al., Phys. Rev. B, 80 (2009) 245411.
Merino, P. et al., ACS Nano, 5 (2011) 5627.
Nie, Shu et al., Phys. Rev. B, 85 (2012) 205406
P2
Quantum Interference In Tunneling Through A Molecular
Kondo System
1
1
1
1
2
I. Fernandez-Torrente , M. Ruby , T. R. Umbach , B. W. Heinrich , J. I. Pascual , K. J.
Franke
1
1
Institut für Experimentalphysik, Freie Universität Berlin, Germany 2 CIC Nanogune, Donosti-San
Sebastián, Spain
The origin of the Kondo effect is understood as a scattering process between an unpaired spin
located at a magnetic impurity and the surrounding spins of the conduction electrons. In
Scanning Tunneling Spectroscopy (STS) experiments this effect causes a sharp resonance
around zero bias, with a lineshape that depends on the balance between different competing
tunneling pathways in the tip/unpaired spin/surface junction. The resonance´s lineshape is
described by a lorentzian curve for the case of a preferential tunneling through the unpaired
spin, and shows an increasing asymmetry for higher contributions of direct tunneling pathways
into the surface. Here we study the variation of the above described lineshape in a charge
transfer monolayer formed by Na atoms and TNAP (tetracyanonaphtoquinodimethane)
molecules deposited on a Au(111) surface. The electron donated by the Na atoms is localized
in the single occupied molecular orbital (SOMO) of the acceptor TNAP [1] and gives rise to the
Kondo resonance in STS spectra [2]. We observed intramolecular changes in the shape and
intensity of the resonance along the TNAP backbone, with a symmetry change at the nodal
planes of the singly occupied molecular state. Through the analysis of these lineshape
variations we can locally map the relative weight of the different tunneling pathways existing
in the metal-molecular system.
T.R. Umbach, I. Fernandez-Torrente, M. Ruby, F. Schulz, C. Lotze, R. Rurali, M. Persson, J.I. Pascual, K.J. Franke.
New Journal of Physics, Vol. 15, page 0830048 (2013)
I. Fernandez-Torrente, K. J. Franke, J. I. Pascual. Physical Review Letters, Vol. 101, page 217203 (2008)
58
P3
Mechanical Force Modulates the Unfolding Pathways of the
Cold-Shock Protein B from Thermotoga Maritima
1,2
3, 4
Jörg Schönfelder , Raul Perez-Jimenez , Victor Muñoz
1
1,2,5
IMDEA Nanociencia, Faraday 9, Cuidad Universitaria Cantoblanco 28049, Madrid, Spain. Tel: +34 91
2
299 8878; CNB, Centro Nacional de Biotecnologia, Darwin 3, Cuidad Universitaria Cantoblanco, 28049
3
Madrid, Spain, Tel: +34 91 585 5422; CIC NanoGUNE, Tolosa Hiribidea, 76, 20018 San Sebastian, Spain,
4.
5
Tel: +34 943 57 4009; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain; University of
Maryland, Department of Chemistry and Biochemistry, College Park, MD, USA
The fundamental concept of reconstructing experimentally the (un)folding energy landscape
(FEL) of any protein structure is to study its conformational dynamics and stability in order to
track its folding reaction. Over the last decades Single Molecule Force Spectroscopy (SMFS) has
become an essential experimental technique allowing investigating protein dynamics through
the application of a mechanical force.[1,2] In our work the characterized cold-shock protein B
from Thermotoga Maritima (TmCSP) has been found to follow a multi-state unfolding scenario
when applying a mechanical force, whereas it folds/unfolds within a conventional 2-state
mechanism when using a chemical denaturant using Single Molecule Fluorescence
Spectroscopy (FRET).[3] This strongly suggests that mechanical force can be used as a probe to
investigate otherwise hidden intermediates in the (un)folding FEL of the TmCSP.
Our approach is to probe the mechanical properties of TmCSP experimentally using the Atomic
Force Microscope (AFM) in both the constant velocity and the constant force modes. In these
modes the AFM cantilever applies a mechanical force on the single protein either uncontrolled
(constant velocity) or controlled by using a PID feedback loop (constant force). The chosen
small 66 residue cold shock protein B from Thermotoga maritima consists of 5-beta sheets
forming a compact barrel. Additionally it is an ideal candidate to conduct SMFS experiments as
it has a small but detectable unfolding force of 70pN[4]. It is also decribed to fold very fast to
completion in ms range[5]. In order to conduct the single molecule force spectroscopy
experiments we built one polyprotein construct using biomolecular techniques consisting of
the TmCSP domain flanked by three Titin I27 domains on each side. Combining experiments
with an AFM (PicoForce ,VEECO) working at constant velocity and a Force Clamp AFM (Luigs &
Neumann), which operates at constant force, we were able to detect and measure the
mechanical unfolding patterns of the individual´TmCSP domain.
First, in our results we could confirm the single-step mechanical unfolding behavior of the
TmCSP[4] in constant velocity mode working in the high force regime. However in force ramp
and in constant force experiments working in the low force regime 20-80pN with the Force
Clamp AFM we were able to detect a high fraction of traces that display complex mechanical
unfolding of TmCSP resembling a clear multi-state unfolding behavior. Furthermore we found
that there is a certain force regime exsisting at wich the amount of unfolding intermediates is
highest. Hence the mechanical unfolding pathway of TmCSP can be modulated by the applied
force in the low force regime.
[1]. Nagy et al. Nat Methods. 2008 5(6):491-505.
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[2]. M. Schlierf, H. Li, and J. Fernandez. PNAS. 2004, Volume 101, 19, 7299-7304
[3]. B. Schuler, E. Lipman, W. Eaton, Nature. 2002, Volume 419, 743–747
[4]. T. Hoffmann, K.M. Tych, D.J. Brockwell, and L. Dougan, J. Phys. Chem. B 2013, 117, 1819−1826
[5]. F.X.Schmid et al, Nature Struct. Biol. 1998, Volume 5, Number 3, 229-35
P4
Replication Initiation Proteins Studied With Atomic Force
Microscopy
1
2
2
Maria Eugenia Fuentes-Perez , Katarzyna Wegrzyn , Igor Konieczny , Fernando
Moreno-Herrero
1
1
Department of Macromolecular Structures, Centro Nacional de Biotecnologia, CSIC, Darwin 3, 28049
Cantoblanco, Madrid, Spain. 2 Department of Molecular and Cellular Biology, Intercollegiate Faculty of
Biotechnology, University of Gdansk, Gdansk, Poland.
DNA replication is a fundamental cellular process whose mechanism is still not well
understood. Replication requires a specific DNA region, known as the origin of replication (Ori),
as well as specific proteins, called replication initiation proteins (Rep). Both DNA and proteins
form the replication initiation complex. The origin of replication in plasmids and phage DNA
contains some conserved elements. These include specific binding sites (iterons) for Rep
proteins, DnaA boxes for DnaA proteins and an AT-rich region where DNA melting occurs. In
this work, we used the Atomic Force Microscope (AFM) to study the binding of Rep proteins to
the origin of replication in the broad-hostrange plasmid RK2 [1]. The origin of replication in
RK2 plasmid is called OriV. It possesses 5 iterons where the replication initiation protein TrfA
binds, four DnaA boxes for DnaA proteins and four 13-meres in the AT rich region [2]. Using
the AFM, we were able to capture the binding of TrfA to the iterons region. Interestingly, while
bound to the iterons, TrfA also interacts with a ssDNA oligonucleotide containing the sequence
of one of the strands of the AT rich region. Moreover, the TrfA-ssDNA interaction is dependent
on the sequence of the oligonucleotide. Our AFM approach was also applied to RepE protein, a
replication initiation protein from plasmid F. Notably, we found that binding of RepE was also
favored by the equivalent ssDNA oligonucleotide of the AT-rich region of plasmid F. These
findings enable to create a general model in which firstly, Rep proteins induces the melting of
the AT-rich region and secondly, specific interaction of Rep protein with one of the melted
ssDNA occur.
Doran, K.S., I. Konieczny, and D.R. Helinski, Replication Origin of the Broad Host Range Plasmid RK2. Journal of
Biological Chemistry, 1998. 273(14): p. 8447-8453.
Rajewska, M., K. Wegrzyn, and I. Konieczny, AT‐rich region and repeated sequences–the essential elements
of replication origins of bacterial replicons. FEMS microbiology reviews, 2011. 36(2): p. 408-434.
60
P5
Design an Iterative Learning Observer to Reconstruct the
Interaction Force in AM-AFM
F. Payam, D. Martin-Jimenez, R. Garcia
Extracting the time varying tip-sample interaction force in dynamic atomic force microscopy
has been an important goal to improve the imaging capabilities of AFM with simultaneous
measurements of material properties [1-4]. Here, we design an Iterative Learning Observer to
reconstruct the interaction force from the wave profile of the cantilever. In this method, the
interaction force is considered as an unknown time varying parameter and estimated by the
designed observer.
Simulations and experiments prove the accuracy of this method in liquid and air for different
materials. From the reconstructed force signals, we are able to obtain the average peak force,
and consequently, using Hu and Raman equation [5], the Young modulus of the materials.
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(a) Topography image of Polystyrene (PS) and Polyolefin Elastomer (LDPE) blend. (b) Signal and
reconstructed force of PS (A0=78nm) (c) Signal and reconstructed force of LDPE (A0=78nm).
M. Stark, R,W.Stark, W.M. Heckl and R. Guckenberger, PNAS, 99, 13, 8473-8478, (2002).
J. Legleiter, M. Park, B. Cusick and T. Kowalewski, PNAS, 103, 13, 4813-4818, (2006).
S. Santos, K. Gadelrab, J. Font and M. Chiesa, New Journal of Physics, 15, 083034, (2013).
A. Sikora and L. Bednarz, Meas. Sci. Technol., 22, 094005 (2011).
S. Hu and A. Raman, Appl. Phys. Lett., 91, 123106, (2007).
P6
STM And Nc-AFM Investigation Of Submonolayer Copper
Oxide Structures
1
1
Carmen Ocal , Esther Barrena , Sonia Matencio
1
1
Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Spain
61
With the aim of obtaining laterally heterogeneous surfaces with catalytic properties,
submonolayer coverages of ultrathin copper oxides on Cu(111) have been grown by air
injection and annealing in UHV [1-3] and investigated by means of STM/nc-AFM. Different
oxide surface structures have been observed depending on the stoichiometric oxygen/copper
ratio, some of which have been already reported [1, 2]. In addition, a new open honeycomb
structure with a relatively large unit cell lattice parameter of ~1.3 nm has been observed that
nucleates and grows at the step edges of the oxide terraces. This oxide structure can be
visualized as an ordered surface network which might serve as nanopattern template for
controlled molecular organization (i.e. in a bottom-up approach). Moreover, derived from the
expected semiconducting character of the oxide, the ultrathin layer would offer as well an
effective electronic decoupling of the organic molecules from the metal surface.
José A. Rodriguez, Journal of Physical Chemistry C 114, 17042-17050 (2010)
C. Pérez León, Physical Review B 85, 035434 (2012)
F. Wiame, Surface Science 601, 1193-1204 (2007)
P7
Structural Control Of Bridge State Resonances In Single
Molecular Junctions
1
1
1
2
2
Carly Brooke , Andrea Vezzoli , Simon J. Higgins , Linda A. Zotti , Juan Jose Palacios ,
1
Richard J. Nichols
1
2
Department of Chemistry. University of Liverpool. Liverpool. United Kingdom Departamento de Física
de la Materia Condensada. Universidad Autónoma de Madrid. Madrid. Spain
In this contribution, we demonstrate structural control over a transport resonance in
HS(CH2)n[1,4–C6H4](CH2)nSH (n = 1, 3, 4, 6) metal | molecule | metal junctions, fabricated
and tested using the scanning tunnelling microscopy- (STM-)based I(s) method. Varying the
number of methylene groups controls a transport resonance associated with the central arene
moiety, in turn leading to a very shallow decay of the conductance with the length of the
molecule. Quantum mechanical control of this phenomenon comes from a Breit-Wigner
resonance in the transmission curves of HS(CH2)n[1,4–C6H4](CH2)nSH which sharpens and
moves closer to the contact Fermi energy as n increases. Such resonances offer future
prospects in molecular electronics in terms of controlling charge transport over longer
distances, and also in single molecule conductance switching if the resonances can be
externally gated. We further demonstrate that the electrical behaviour observed here can be
straightforwardly rationalized, using the ideas of semiconductor physics, in terms of a pair of
back-to-back Schottky diodes.
62
P8
Magnetic Force Microscopy Of Focused Ion Beam Patterned
Co Antidot Arrays
1,3
2
3
3
Andreas Kaidatzis , Rafael Pérez del Real , Raquel Alvaro , Jose V. Anguita , Manuel
2
3
Vazquez , José Miguel García-Martín
1
2
Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, Athens, Greece ICMM-Instituto
3
de Ciencia de Materiales de Madrid, CSIC, Madrid, Spain IMM-Instituto de Microelectrónica de Madrid,
CSIC, Tres Cantos, Madrid, Spain
Continuous magnetic films with patterned groups of ordered holes, known as magnetic antidot
arrays, are being intensively investigated as candidates for high-density storage media [1] and
as magnonic crystals for magnetic logic applications [2]. The main parameters that influence
the magnetic properties of the array are its symmetry and lattice constant and the shape and
size of the antidots. The main focus of antidot arrays studies has been on square or hexagonal
symmetry arrays of circular antidots, on the μm- and sub-μm-scale, fabricated by patterning
methods like UV [3] or e-beam [4] lithography. On the other hand, nm-scale antidot arrays can
be attained by various self-assembly techniques employing, e. g., porous anodic alumina [5] or
colloidal lithography [6]. However, there are significant inherent drawbacks in all of the selfassembly fabrication methods, mainly regarding the limitations in the array symmetry and/or
size and the extent of the symmetric domains, which is on the order of some μm
In this work, nm-scale antidot arrays have been fabricated using focused ion beam
nanopatterning and characterized by magneto-optical Kerr effect magnetometry and
atomic/magnetic force microscopy. Continuous Ti (2 nm)| Co(10 nm) | Au(10 nm) stacks were
evaporated in an ultra-high vacuum chamber on monocrystalline (0001) sapphire substrate.
The substrate was rotated around its normal during the deposition in order to avoid the
formation of strong magnetic anisotropy during the growth of the film. The antidot arrays
63
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were directly etched on the continuous stack using an IonLine FIB machine, with Ar ions at
energy of 30 keV and ion current of 6.9 pA. Square and hexagonal symmetry arrays have been
studied with lattice constant ranging from 150 nm to 300 nm and antidot diameter 55 nm, see
Fig. 1. We find an intense increase of the magnetic coercivity (Hc) of the film after patterning,
with a monotonic increase of Hc as the density of defects increases. Additionally, the in-plane
anisotropy axes of the patterned film depend strongly on the array symmetry, with alternating
hard and easy axes following the array symmetry. High resolution MFM images reveal the
magnetic structure of the arrays. In clear contrast to the unpatterned film, where abrupt
contrast changes correspond to domain wall dragging under the influence of the magnetic
stray field of the MFM tip (Fig. 2a), the antidot arrays exhibit stable magnetic domains whose
inner structure is commensurate to the array symmetry (Fig. 2b-2d). It is concluded that
nanopatterned anti-dot arrays provide an effective means to engineer the magnetic properties
of thin films.
Figure 1. Atomic force microscopy images revealing (a) the
global morphology of a representative antidot array and (b)
the two array symmetries studied and the antidot shape and
size.
Figure 2. MFM images of (a) unpatterned Co film,
(b) hexagonal antidot array demagnetized along 0o,
(c) square antidot array demagnetized along 45o,
and (d) square antidot array demagnetized along
30o
C. Wang et al., Nanotechnology 17, 1629 (2006)
R. Bali et al., Phys. Rev. B 85, 104414 (2012)
L. J. Heyderman et al. Phys. Rev. B 73, 214429 (2006).
P. Vavassori et al. Phys. Rev. B 59, 6337 (1999).
D. Navas et al. Appl. Phys. Lett. 90, 192501 (2007).
M. E. Kiziroglou et al. J. Appl. Phys. 100, 113720 (2006).
Acknowledgments Funding from CSIC (i-LINK0783), MINECO (MAT2011-29194-C02-01, MAT201020798-C0501 and CSD2008-00023) and EU (PIEF-GA-2010-272470) is acknowledged.
P9
Investigating Subsurface Boron Dopants In Si(111)-(√3x√3) R30°
Using Simultaneous Nc-AFM/STM And DFT
1,2
1
1
1
Jan Berger , Evan J. Spadafora , Pingo Mutombo , Mykola Telychko , Martin
1
1
3
1
Ondráček , Martin Švec , Alastair McLean , Pavel Jelínek
64
1
Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic 2 CTU Prague,
Faculty of Nuclear Sciences and Physical Engineering, Czech Republic 3 Department of Physics, Queens
University, Kingston, Ontario, Canada
B:Si(111)-(√3x√3)R30° surface has gained a lot of interest in surface science, due to its
prominent electronic and structural properties. Compared to bare silicon surface, this system
has reduced chemical reactivity, which makes it a suitable candidate for deposition of
molecular complexes without a risk of their decomposition. Here, we investigated the near
surface defects of this delta-doped system using a combination of scanning tunneling
microscopy, non-contact atomic force microscopy, ab initio and Green function theoretical
methods. We make positive assignments of two near surface defects: the adatom vacancy and
a B substitutional defect that is located in the second Si bilayer. We also confirm the previously
reported assignment of the dangling-bond defect. Additionally, the influence of the subsurface
defects on the surface electronic structure, in particular the modulation of the surface
potential, is investigated using Kelvin probe force microscopy, scanning tunneling spectroscopy
and large scale density functional theory calculations. The effects of solitary dopants can play a
significant role on commercial device performances as well as on the fundamental local
properties of a semiconductor. Therefore, this study paves the way for a deeper understanding
of passivated Si surfaces used for the development of molecular thin films and devices.
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P10
Probing The Fermi Surfaces Of The Two-band Superconductor
Lead
1
1
2
B. W. Heinrich , M. Ruby , J. I. Pascual , K. J. Franke
1
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Institut für Experimentalphysik, Freie Universität Berlin, Germany CIC NanoGUNE and Ikerbasque,
Donostia-San Sebastian, Spain
Recent density functional theory simulations have shown that the two separated Fermisurfaces of the strong-coupling s-wave BCS superconductor lead (Pb) exhibit different
character in momentum space, namely s-p- and p-d-like [1]. The two Fermi-surfaces make Pb a
two-band superconductor with a different gap parameter for each band. We use scanning
tunneling microscopy and spectroscopy at 1.2 K to experimentally probe the two-band
superconductivity of lead on low-index surfaces of Pb single crystals. In the excitation
spectrum, we observe for all surfaces two quasi-particle resonances at each side of the gap,
which appear due to the two gap parameters. They have an energy difference of 150 µV and
differ remarkably in intensity. We then use dI/dV mapping around subsurface defects to
characterize the two Fermi surfaces in real space -similar to the Fermi surface mapping of a
one-band conductor in Ref. 2. Furthermore, we study the influence of lead adatoms on the
tunneling spectra, unveiling different localization characteristics for the two bands.
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A. Floris et al., Phys. Rev. B 75, 054508 (2007).
A. Weismann et al., Science 323, 1190 (2009).
P11
Boron- and Nitrogen-doped Multiwall Carbon Nanotubes
Studied By Kelvin Probe Microscopy
J. F. González-Martínez 1, J. Abad2, J.-S. Park3, J.-M. Lee3,4, S.-O. Kim3,4, J.-S. Kim3,5, A.
Urbina5,2 and J. Colchero1
1
2
Department of Physics, University of Murcia, Campus Espinardo, 30100 Murcia, Spain; Departments
of Applied Physics and Electronics, Technical University of Cartagena, Plaza Hospital 1,30202 Cartagena,
3
Spain; Department of Materials Science and Engineering, Korea Advanced Instituteof Science and
4
Technology (KAIST), 305-701, Daejeon, Republic of Korea; Center for Nanomaterials and Chemical
5
Reactions, Institute for BasicScience (IBS), Daejeon 305-701, Republic of Korea; Department of Physics
and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, UK
Carbon nanotubes have been thoroughly studied in the past twenty five years because of their
exceptional physics properties. However, in recent years a great interest has been observed
towards improving and controlling their properties through different functionalization
methods. The modification of the nanotube properties by controllably placing defects or
heteroatoms can lead to huge technological implications [1]. The introduction of hetero-atoms
such as Nitrogen or Boron into Carbon Nanotubes offers the possibility of tailoring their
structural and electronic properties [2]. In particular, substitution of Boron or Nitrogen in
Carbon nanostructures can render them p-type or n-type, respectively. Nitrogen-doped multiwalled Carbon Nanotubes (MWNTs) exhibit interesting electrical transport properties, as a
higher conductance than undoped ones [3]. Besides, nitrogen-doped MWNTs exhibit excellent
electron emission behaviour [4]. While for boron-doped MWNTs a metallic character and an
enhanced resistance towards oxidation have been reported. In this work we have investigated
undoped, and boron- and nitrogen-doped MWNTs which have been previously used to
fabricate organic solar cells [5] and characterized by Raman spectroscopy [6]. The experiments
presented in this communication have been performed by means of Electrostatic Force
Microscopy (ESF), Kelvin Force Microscopy (KPM) and 3D modes including force spectroscopy,
66
in ambient and vacuum conditions. Bundles and individual multiwall nanotubes have been
studied on a graphite substrate, allowing us to obtain the work function by direct
measurement using the substrate graphite signal for proper calibration and therefore
identifying the p-type and n-type character of the doped nanotubes. The understanding of
doping effects on the electronic performance of devices based on carbon nanotubes is a
crucial point for the development of nanotube-based nanoelectronics and to the discovery of
new functionalities.
M. Dresselhaus, G. Dresselhaus, P. Avouris. Carbon nanotubes: synthesis, structure, properties, and
applications. ( Springer-Verlag, Germany, 2001)
O. Stéphan, P.M. Ajayan, C. Colliex, P. Redlich, J.M. Lambert, P. Bernier, P. Lefin, Science 266, 1683 (1994)
R. Sen, et al, Chem. Phys. Lett. 287, 671 (1998)
M. Doytcheva et al. , Chem. Phys. Lett. 396, 126 (2004)
J. M. Lee, J. S. Park, S. H. Lee, H. Kim, S. Yoo and S. O. Kim, Adv. Mater. 23, 629 (2011)
A. Urbina, J. S. Park, J. M. Lee, S. O. Kim and J.-S. Kim, Nanotechnology 24, 484013 8 (2013)
P12
Calibration of Normal Force using non-destructive Dynamic
Force Microscopy
Juan Francisco González Martínez1, Jaime Colchero Paetz1
1
Instituto Universitario de Investigación en Óptica y Nanofísica, Campus de Espinardo, Universidad de
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A method to precisely calibrate the normal force based on Dynamic Scanning Force
Microscopy techniques is described. Many methods have been proposed to calibrate the
deflection of the cantilever [1- 3]. We recall here two of them: the first one based on
measurement of the slope of a force distance curve while the second one is based on the
equipartition theorem,
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kB T /2= c zth2/2
(1)
(kB, the Boltzmann constant; T, temperature; c, the force constant of the cantilever and zth, the
displacement of the free end of the cantilever). We recall relation (1) has two unknowns, the
force constant c and the sensitivity β of the detection system that converts the signal in volts,
u(t) into nanometers: z(t)= β u(t). If the force constant c is known (for example, using Sader’s
method [4]), then the thermal noise relation (1) can be used to determine the sensitivity β,
that is, the calibration of the normal force.
In the present work we will describe how to calculate the sensitivity using Dynamic Force
Microscopy techniques. Essentially, we adapt a method to calibrate the oscillation amplitude
[5] based on thermal noise, and will show that the results agree well with the classical
determination of sensitivity as calculated from force vs. distance curves. The method proposed
in this work uses the thermal noise through the electronics used to process the signals in
Dynamic Force Microscopy. This methods has the following advantages,
1. It is possible to calibrate the normal force and the oscillation amplitude [5]
simultaneously.
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2. A better signal to noise ratio is obtained due to Dynamic Electronics and the lower
bandwidth of electronics.
3. The method is “non-contact”, therefore even for very sharp tips their integrity is
preserved.
Experimentally the method proposed works up to cantilevers with c<70 N/m, otherwise there
are still unsolved difficulties.
R. S. Gates et al., J. Res. Natl. Inst. Stand. Technol. 116, 703–27 (2011).
J. te Riet et al., Ultramicroscopy 111, 1659–69 (2011).
N. A. Burnham et al., Nanotechnology 14, 1–6 (2003).
J. E. Sader, J.W.M. Chon and P. Mulvaney, Rev. of Scien. Inst. 70, 3967-9 (1999).
J. F. González Martínez, I. Nieto-Carvajal, J. Colchero, Nanotechnology 24, 185701 (2013).
P13
Modelling dissipation in Dynamic Scanning Force Microscopy
as a function of tip-sample distance
Juan Francisco González Martínez1, Jaime Colchero Paetz1
1
Instituto Universitario de Investigación en Óptica y Nanofísica, Campus de Espinardo, Universidad de
Murcia, E-3100, Spain
The quality factor is a key parameter for Dynamic Force Microscopy, since it determines a
series of important properties of the system, such as the energy stored in the system, the
width of the resonance curve, the resonance enhancement, but also the response to nonlinear interactions, and the response of a Phase-Locked Loop in the so called Frequency
Modulation mode. For operation in non-vacuum environment –that is in air or liquids, the
quality factor is essentially determined by the surrounding viscous medium. In the present
work the behaviour of a Scanning Force Microscopy (SFM) cantilever in viscous media is
studied, with particular emphasis on how the viscosity of these media reduces the quality
factor. A simple theoretical model is proposed based on the assumption of a composed probe
model:
SFM probe = microscopic cantilever + mesoscopic tip cone + nanometric tip apex
This model correctly describes the dissipation for a variety of cantilevers in different media (fig.
1). It is shown that the physical dimensions of the cantilever as well as the viscosity of the
medium where it is immersed determine the dependence of the quality factor with the
cantilever-sample distance. For the range of distances explored in this work, it is shown that
the Reynolds number is a key parameter to select a cantilever in a specific medium, in order to
achieve the highest quality factor at small cantilever-sample range.
68
Figure 1: This graph shows the dependence of the quality factor with distance for different media (air, water,
ethanol, toluene and acetone). Note that for better visibility the curve in air has been divided by 10. The Reynolds
number (Re) for each case has also been added. In this particular case, a silicon nitride cantilever (length, 100
microns; width, 20 microns; elastic constant, 0.04 N/m) has been used.
P14
Structure–performance Relationships In Solution-processed
Organic Solar Cells Based On Acceptor-substituted S,N
Heteroacenes
1,2
1
1
1
Marta Urdanpilleta , Hannelore Kast , Amaresh Mishra , Gisela L. Schulz , Elena
1
Mena-Osteritz , Peter Baeuerle
1
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Institute of Organic Chemistry II and Advanced Materials, University of Ulm, AlbertEinstein-Allee 11 D-
89081 Ulm, Germany 2 Dpto. Física Aplicada I, Universidad del País Vasco (UPV/EHU),Pl. Europa 1, 20018
Donostia, Spain
The application of organic materials for the photovoltaic conversion corresponds to the third
generation of solar cells. These systems are gaining ground to the classical siliconbased ones,
due to their mechanical flexibility, low weight, low cost and eco-friendly potential.
The synthesis of oligomers is emerging as a viable strategy to expand the structural diversity
relevant to organic electronic applications. The advantage of the oligomeric (or small
molecule) approach is that they are defined, monodispersed molecules able to crystallize: the
structure-properties relationship of the photovoltaic devices employing oligothiophenes can
be thus univocally established.
The solar cell devices based on small molecules are recently attracting increasing attention
because of their advantages above conjugated polymeric systems in terms of easiness of
purification, higher homogeneity between batches, and therefore higher reproducibility
concerning efficiency of the devices. Power conversion efficiencies (PCE) up to 6.9% have been
reported for oligomers based on vacuum-processed [1] and 9% for solutionprocessed single
junction devices [2,3]. For this type of devices, probe microscopy can give insights into the
morphological distribution of the donor and acceptor within the blend of the photoactive
layer, a crucial parameter for the cell performance. Nanometersize phase separated domains
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are necessary to accomplish the needs of exciton diffusion, charge separation and charge
carrier transport in the organic photoactive film.
Fused oligomers such as acenes and heteroacenes have attracted growing attention not only
with respect to the design of new materials but also for their applications in organic field effect
transistors (OFET) and organic solar cells (OSC). As an example, pentacene have shown high
2
-1 -1
2
-1 -1
hole mobility of up to 5 cm V s in bulk and up to 40 cm V s in single crystal [4].
In this contribution, the surface properties of solar cell devices based on acceptorsubstituted
fused heteroacenes as a donor material have been studied with atomic force microscopy
(AFM), and results correlating the solar cell performance and the surface characteristics will be
discussed.
R. Fitzner, E. Mena-Osteritz, A. Mishra, G. Schulz, E. Reinold, M. Weil, C. Körner, Ziehlke, C. Elschner, K. Leo,
M. Riede, M. Pfeiffer, C. Uhrich and P. Bäuerle, J. Am. Chem. Soc., 134 (2012) 11064
J. Zhou, X. Wan, Y. Liu, Y. Zuo, Z. Li, G. He, G. Long, W. Ni, C. Li, X. Su and Y. Chen, J. Amer. Chem. Soc., 134
(2012) 16345
V. Gupta, A. K. K. Kyaw, D. H. Wang, S. Chand, G. C. Bazan, A. J. Heeger, Sci. Rep. 3 (2013) 1965
J. Mei, Y. Diao, A. L. Appleton, L. Fang, Z. Bao, J. Am. Chem .Soc. 135 (2013) 6724
P15
Ether Groups And Acyl-chain Branching Reduce
Nanomechanical Resistance Of Phospholipid Bilayers: A Force
Spectroscopy Study
1,2
1,2
1,2
1,3
Aritz B. García-Arribas , Jesús Sot , Daniel Balleza , Kepa Ruiz-Mirazo , Alicia
1,2
Alonso , Félix M. Goñi
1
1,2
Unidad de Biofísica (Centro Mixto CSIC, UPV/EHU), Leioa, Spain. 2 Departamento de Bioquímica,
Universidad del País Vasco (UPV/EHU), Leioa, Spain. 3 Departamento de Lógica y Filosofía de la Ciencia,
UPV/EHU, Av. Tolosa 70, 20018 Donostia-San Sebastián, Spain.
Atomic force microscopy (AFM) has been applied to the characterization of nanomechanical
resistance of lipid bilayers to study the effect of ether-linking and acylchain branching. For this
purpose, supported planar bilayers (SPBs) were obtained from small unilamellar vesicles
(SUVs) of pure lipids by the vesicle adsorption method onto mica substrates and analysed by
force spectroscopy at 23 ºC. Lipids studied were dipalmitoyl phosphatidylcholine (DPPC, ester
group, nonbranched acyl-chain), dihexadecyl phosphatidylcholine (DHPC, ether, nonbranched),
diphytanyl phosphatidylcholine (DPhPC, ether, branched) and diphytanoyl phosphatidylcholine
(DPhoPC, ester, nonbranched). The presence of ether groups and acyl-chain branching both
enhance fluidity: nonbranched lipids (DPPC, DHPC) form lamellar gel phases at 23 ºC, whereas
branched lipids (DPhPC, DPhoPC) form lamellar fluid phases, with lower breakthrough forces.
DPhPC, both ether-linked and branched, yields the lowest breakthrough force values. DPhoPC
exhibits higher breakthrough force values than typically expected in a fluid phase. Special
properties of this lipid have been reported: e.g. abnormally low water permeabilization when
compared to other fluid-phased phosphatidylcholines such as POPC or DOPC [1]. In the case of
70
DHPC, SPB imaging reveals transient coexistence of two different lamellar gel-phases at 23 ºC,
due to the lack of equilibrium, and a suggested metastable interdigitated gel phase is observed
[2], with reduced thickness and higher breakthrough force. Ether-linked and acyl-branched
(isoprenoid) lipids are common in Archaea (as sn-glycerol-1-phosphate isomers) and this study
becomes relevant in the context of the “lipid-divide” hypothesis and the development of early
membranes of the evolutionary precursors of cells.
[1]. S. Tristram-Nagle, D.J. Kim, N. Akhunzada, N. Kučerka, J.C. Mathai, J. Katsaras, M. Zeidel, and J.F. Nagle.
Chem. Phys. Lipids. 163:630–637 (2010).
[2]. S.D. Guler, D.D. Ghosh, J. Pan, J.C. Mathai, M.L. Zeidel, J.F. Nagle and S. Tristram-Nagle. Chem. Phys. Lipids.
160:33-44 (2009).
P16
Understanding Transverse Shear Microscopy In Crystalline
Organic Layers
1
2
1
A. Pérez-Rodríguez , A. Fernández , C. Ocal , E. Barrena
1
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2
Institut de Ciéncia de Materials de Barcelona, Campus de la UAB, 08193, Bellaterra, Spain Graz
University of Technology,8010 Graz, Austria
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Over the past two decades conventional lateral force microscopy (LFM) also known as friction
force microscopy (FFM), has become the primary tribological technique for examining surfaces
frictional response at nanometer scale. LFM detects the cantilever torsion resulting from
frictional forces between tip and surface by setting the fast-scan direction orthogonal to the
cantilever axis. However, the torsion signal may also be collected by setting the fast-scan
direction parallel to the cantilever axis. Recently, this imaging mode has been referred to as
transverse shear microscopy (TSM) [1]. The TSM signal provides a rich map of contrasts in
molecular crystals that has successfully been employed for revealing the azimuthal orientation
of crystalline domains in crystals and thin films of pentacene [1,3] and hydrogen phthalate[3].
The relation between the TSM signal and the crystallographic directions of the molecular
surface has been demonstrated.
S
However, the quantitative interpretation of the rather surprising TSM contrast in organic
materials is controversial [2,3]. Here we perform a TSM and LFM study of N,N′-dioctyl-3,4:9,10perylene tetracarboxylicdiimide (PTCDI-C8 ) with the goal of gaining understanding on the
origin of TSM in molecular surfaces. Unlike the two previously investigated molecules, PTCDIC8 does not order in a herringbone structure but in rows of co-facially stacked molecules with
a tilt of ~35-40° respect to the vertical. For this study two-dimensional crystalline islands of
PTCDI-C8 have been grown on silicon dioxide at submonolayer coverage. We have performed
molecular-resolution images in different domains and compared the TSM and LFM response in
relation to the orientation of the resolved lattice. The stick-slip motion in TSM and LFM and its
dependence with the applied load have also been studied.
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V. Kalihari et al. Adv. Mat. (2008), 20, 4033
M. Campione et al. PRL 105, 166103 (2010)
V. Kalihari et al. PRL 104, 086102 (2010
P17
α-Fe2O3(0001) Surface As A Model Catalyst: Morphology And
Electronic Structure
1,2
2
Sara Barja , Alexander Weber-Bargioni , Miquel Salmerón
1
1,2,3
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States. 2
Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, United States. 3 Department
of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, United States
Semiconductor based photo-catalysts have been studied for many years as a potential solution
for clean, large-scale hydrogen fuel production, as well as to degrade pollutants in
contaminated water. However, the efficiency of these processes is still too low to be practical.
Fundamental understanding of the correlation between catalyst’s morphology, energy level
alignment between catalyst and reactant and the local photo catalytic activity is crucial for a
systematic optimization of the mechanisms behind photo catalytic reactions, a key to enhance
the impact of green chemistry 1. Here, we present our first results correlating surface
morphology, surface electronic structure and local distribution of photo excited carriers with
atomic resolution in the α-Fe2O3(0001) model catalyst. Our tool is Low Temperature Scanning
Tunneling Microscopy/Spectroscopy in Ultra High Vacuum with and without band gap
illumination (480 nm). α-Fe2O3(0001) single crystal – hematite phase- exhibits fundamental
properties ideal as a model system for solar catalytic process: it is an n-type semiconductor
with a band gap of approximately 2.2 eV, earthabundant, relatively easy to synthesize, cheap
and environmental benign. In addition, depending on the different conditions of temperature
and oxygen partial pressure during αFe2O3(0001) single crystal preparation under Ultra High
Vacuum conditions, a mixture of Fe2O3 (0001), Fe3O4 (111) and FeO (111) surfaces is
commonly observed 2,3. In particular, in this work we show how the local electronic structure
of the Fe3O4 (111) surface domain is modified due to the presence of different point-defects
72
(Fe- or Ovacancies and Fe- adatoms) that have each a unique signature in the tunneling
spectra. We found that under illumination the distribution of photo excited carriers is
governed by the local surface potential variations. Hence, by comparing the electronic
structure under illumination to the one obtained in the dark, we can determine the
distribution of optically excited charge carriers that will drive the photochemical reaction. Our
ultimate goal is to understand and eventually predict how the morphology, optically excited
electronic structure and local photo catalytic rate are correlated for a systematic development
of novel artificial photo catalytic systems.
[1]. Walter, M. G. et al. Chemical Reviews 110, 6446–6473 (2010).
[2]. Condon, N. G. et al.). Surface Science 397, 278–287 (1998).
[3]. Tang, Y., Qin, H., Wu, K., Guo, Q. & Guo, J.. Surface Science 609, 67–72 (2013).
[4]. Yin, S. & Ellis, D. E.. Surface Science 602, 2047–2054 (2008).
P18
Surface Charge Differentiation of Avidin and Streptavidin By
AFM-Force Spectroscopy
L. Almonte, E. López-Elvira, A.M. Baró
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Instituto de Ciencia de Materiales de Madrid-CSIC, Madrid, Spain
Chemical analysis of matter consists of the determination of either elemental or molecular
composition. The amount of material required for chemical analysis has decreased
continuously as increasingly sensitive analysis tools have become available. Atomic force
microscopy (AFM) is a powerful technique for studies of biological samples due to its ability to
measure forces in real time and in liquid media with atomic or molecular resolution [1]. In
addition chemical information can be obtained by Force Spectroscopy (FS), which is based on
the measurement of force vs. distance curves F(d) in the pN range.
In this it work has been possible to distinguish between single molecules of avidin and
streptavidin anchored to a biotinylated bilayer even though AFM topographic images of both
proteins cannot be distinguished, because their protein structures are almost identical. This
differentiation can be achieved due to the different surface charge of both proteins. Indeed,
avidin is a basic glycoprotein, pI = 10.5, so that avidin is positively charged [2] whereas
streptavidin is non-glycosylated with a near-neutral pI at pH=7. This charge difference has
been determined by AFM which can probe electrostatic double layer (EDL) forces by FS. The
F(d) curves due to the electrostatic interaction have significant differences when measured on
top of each molecule of streptavidin and avidin (figure 1(a)) as well as on the lipid substrate
where they are fixed. Figure 1(b) shows the normalized force values to tip radius obtained for
both proteins as well as for supported lipid bilayer (SLB). Moreover, FS data show that the two
proteins are negatively charged since the curves are repulsive. Notwithstanding avidin and
streptavidin can be clearly distinguished, which shows the sensitivity of AFM to detect the
charge state of macromolecules.
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J. Sotres, A.M. Baró, Biophys. J. 98, 1995-2004 (2010)
M.D Savage, G. Mattson, S. Desai, G.M. Nielander, S. Morgensen, E.J. Conklin, Avidin-Biotin Chemistry: A
nd
Handbook, 2 ed. (Pierce, Rockford. 1994)
P19
Amplitude modulation dynamic force microscopy for stable
imaging of samples with heterogeneus in liquids
Lisa Almonte1, Arturo M. Baró1, Jaime Colchero2
1
Instituto de Ciencia de Materiales de Madrid-CSIC, Campus de Cantoblanco E-28049 Madrid
2
Dep. Física. CIOyN. Universidad de Murcia, Campus Espinardo, E-30100 Murcia
Scanning Force Microscopy (SFM) is a powerful tool in the field of Biology and Biophysics due
to its ability to image and measure forces of in-vivo biological samples in physiological
environment. Biological samples in liquid medium have a surface charge that may be repulsive
or attractive depending on local charge of the sample in the medium at a specified pH. To
modify or damage the sample as little as possible is important to measure in the non-contact
regime. For samples with different local charge domains (“heterogeneous-charge” samples)
the acquisition of electrostatic measurements cannot be performed in jumping or frequency
modulation (FM-DSFM) in the non-contact regime, because the feedback loop needs a welldefined slope of the interaction curve (normal force and frequency shift). On different charge
domain this slope is different (attractive or repulsive) leading to unstable imaging (Fig. 1). The
dissipation however, the other DSFM channel related to amplitude, is monotonous. Amplitude
modulation (AM-DSFM) is therefore the only technique for stable SFM-images of
“heterogeneous-charge” samples.
In this work a lipid bilayer (DOTAP) on mica has been measured in milli-Q water.
Frequency shift, phase and amplitude channels are acquired simultaneously with normal force
as an additional information channel. Amplitude modulation and frequency modulation have
been compared at low oscillation amplitude in dynamic modes: at constant amplitude good
topography has is obtained with the correct height (6 nm). This mode is reproducible and nondestructive since low forces are applied. At constant frequency wrong height (3.5nm) has been
obtained. In addition, high forces are applied so this mode is destructive if the measurement is
instable.
74
Normal Force (pN)
Repulsive
Force
Tip-Sample Distance (nm)
Attractive
Force
Fig 1. Attractive and repulsive regime in force-distance curves.
[1] C. Gotsmann, et al., the American Physical Society, 11051 (1999)
[2] Johnson A.S. et al., Langmuir 19:10007 (2003)
P20
Detecting charging effects in single molecules by nc-AFM
Fabian Schulz1,2, Christian Lotze1, Martina Corso1,3,4, Isabel Fernandez-Torrente1,
Katharina J. Franke1, J. Ignacio Pascual1,3,5
1
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2
Freie Universität, Berlin, 14195, Germany; Aalto University School of Science, Espoo, 01250, Finland
3
4
5
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IKERBASQUE, 48011, Bilbao, Spain; Material Physics Center, 20018, San Sebastián, Spain; CIC
nanoGUNE, 20018, San Sebastián, Spain
The ultimate goal in electronic devices miniaturization is the creation of circuit elements (as
wires, transistors, rectifiers…) consisting on single molecules. A single molecule transistor
exploits the electrostatic modulation of a molecule’s orbital energy. To realize such device a
high degree of charge localization is needed in order to allow for discrete changes in
transconductance of the molecular device [1]. Charge localization requires minimal
hybridization between the molecular orbitals and the states of the leads, and the possibility to
tune the charge state of the molecule. Scanning probe techniques offer the unique possibility
of addressing such issues in studying single molecules with atomic precision. Scanning
tunneling microscopy (STM) has proven its potential to discriminate and manipulate the
charge state of single atoms and molecules [2]. Non-contact atomic force microscopy (nc-AFM)
allowed as well determining the charge state of those systems [3]. Nevertheless the dynamic
response of the AFM to (dis)charging events has been investigated so far for many electron
systems as semiconducting quantum dots [4] or nanoparticles [5].
Here we demonstrate the capability of nc-AFM to achieve single-electron sensitivity in
processes occurring in single molecules.
The electron acceptor molecule TCNQ embedded into a charge transfer compound (TCNQTMTTF) could be (dis)charged by integers of e through gating with the electric field between an
STM tip and the Au(111) supporting surface [6]. The critical field inducing the molecular
(dis)charging could be tuned with the sample bias voltage or the tip-molecule distance. The
latter changes periodically at an oscillating AFM tip. The coupling of the (dis)charging process
resonantly with the periodic motion of the AFM tip, results on a change of the measured
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frequency shift (∆f) due to different electrostatic forces in the junction. By sweeping the
applied sample bias, ∆f exhibits a pronounced deep whenever the molecule changes from a
charged to a neutral state.
[1]. W. Liang, M. P. Shores, M. Bockrath, J. R. Long, H. Park, Nature 417, 725 (2002).
[2]. J. Repp, G. Meyer, F. E. Olsson, M. Persson, Science 305, 493 (2004).
[3]. L. Gross, F. Mohn, P. Liljeroth, J. Repp, F. J. Giessibl, G. Meyer, Science 324, 1428 (2009).
[4]. L. Cockins, Y. Miyahara, S. D. Bennet, A. A. Clerk, S. Studenikin, P. Poole, A. Sachrajda, P. Grutter, PNAS
107, 9496 (2010).
[5]. A. Tekiel, Y. Miyahara, J. M. Topple, P. Grutter, ACSNano 7, 4683 (2013).
[6]. I. Fernández-Torrente, D. Kreikemeyer-Lorenzo, A. Strózecka, K. J. Franke, J. I. Pascual, Phys. Rev. Lett. 108,
036801 (2012).
P21
Two Dimensional Gadolinium Alloys On Noble Metal Surfaces
1,2
Alexander Correa , Bin Xu
1
3,4,5
3,4
, Matthieu Verstraete , Lucia Vitali
2,6
Donostia International Physics Center, 20018 San Sebastian (Spain) 2 Departamento de física de
materiales, Universidad del País Vasco, 20018 San Sebastian (Spain) 3 Départment de Physique,
Université de Liège, Allée du 6 Août 17, B-4000 Sart Tilman, Belgium 4 European Theoretical
Spectroscopy Facility (http://www.etsf.eu) 5 Department of Physics and Institute for Nanoscience and
Engineering, University of Arkansas, Fayetteville, Arkansas 72701 6 Ikerbasque Foundation for Science,
48011 Bilbao (Spain)
The reported fast magnetization switch of thin layers of transition and rare-earth metals or of
their alloys has raised the scientific and technological interest due to their potential application
in spintronics and data storage [1, 2]. The physical principles behind these observations have
not yet been completely clarified: it has been ascribed to the interaction of light with the
electron and spin structure of these systems, while an important role in their relaxation and
coherent magnetic ordering is due to lattice phonons. Given the potentiality of these
observations, it is important to synthesize and characterize these ferromagnetic materials in
different chemical compositions such as in alloys with nonmagnetic materials. This creates a
new crystallographic, electronic and magnetic structure and can result in a modified exchange
mechanism for the magnetic ordering. In this work, we address the structural, electronic and
spin characterization of two novel surface alloys based on gadolinium and noble metal
surfaces, as Au(111) and Ag(111). These form stoichiometric alloys GdAu2 and GdAg2 with one
single Gd atom per unit cell [3,4,5]. These alloys are therefore diluted rare-earth structures,
which exhibit a Curie temperature lowered to only ~30K and an in-plane magneto-crystalline
anisotropy [4,5]. The incommensurability of the lattice constants of the supporting substrate
and of the formed single-layer alloys gives rise to a Moiré structure, where the atoms of the
overlayer are in different registry with the substrate. Topographic and local spectroscopic
characterization of the density of state of these two superstructures have been achieved at
various positions of the Moiré pattern with a scanning tunneling microscope operated at 1
Kelvin. Density functional theory calculations with noncollinear spins have been performed to
deepen our understanding of the similarity and peculiarity of these surface alloys in the local
density of states as well as in their magnetic properties.
76
[1].
C.Stamm et al, Nature Materials 7,740 (2007)
[2]. I.Radu et al., Nature 472,205 (2011)
[3]. M. Corso, M. J. Verstraete, F. Schiller, M. Ormaza, L. Fernández, T. Greber, M. Torrent, A. Rubio, and J. E.
Ortega, et al. Physical Review Letters 105, 016101 (2010)
[4]. L.Fernandez, M.Blanco Rey, M.Llyn, L. Vitali, A.Magaña, A.Correa, P.Ohresser, J.E.Ortega, A.Ayuela,
F.Schiller, submitted for publication
[5]. A. Cavalin, L. Fernandez, M. Ilyn, A. Magaña, M. Ormaza, M. Matena, L. Vitali, J. E. Ortega, C. Grazioli, P.
Ohresser, S. Rusponi, H. Brune, F. Schiller, submitted for publication
P22
Elastic-Plastic Switch Of Tomato Bushy Stunt Virus Particles
1
2
3
2
3
2
A. Llauró , E. Coppari , F. Imperatori , A.R. Bizzarri , L. Santi , S. Cannistraro , P. J. de
Pablo
1
1
Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049. Madrid,
Spain 2 Biophysics and Nanoscience Centre, CNISM-DEB, Università della Tuscia, 01100. Viterbo, Italy 3
Department of Agriculture, Forests, Nature and Energy (DAFNE), Università della Tuscia, Via San Camillo
de Lellis snc, 01100 Viterbo, Italy
The study of virus protein shells mechanics in the elastic regime has provided insights into the
virus strength and structure, such as the rigidity of the shells or the precursors of the
disassembly. However, there is a lack of information about the plasticity of viral cages,
including their molecular and structural determinants, which results in the permanent
deformation of the viral particles without breakage under mechanical load. Here we
investigate the effects of pH and ions sequestration on the mechanics of individual Tomato
Bushy Stunt Virus nanoparticles (TBSV-NPs) by using Atomic Force Microscopy (AFM). Our
experiments demonstrate that the depletion of calcium ions from the intracapsid binding sites
reduces the stiffness of TBSV-NPs and induces an elastic-plastic transition on the mechanical
response of these protein shells. Interestingly, we find that this plastic transition is also
triggered by mechanical deformation. These findings are further supported by a careful
analysis of the virus adsorption geometries on the surface. The structural role of calcium ions
establish an inextricable linkage between the molecular and physical determinants of plasticity
in TBSV-NPs. We suggest that the ability of TBSV-NPs of being permanent deformed without
fracture might not only have implications during the infection of plant cells but also may
increase the stability of these cages for cargo transportation at the nanoscale.
P23
Studying The Mechanical Behavior Of Cardiac Stem Cells By
Means Of Atomic Force Microscope
1,2
1,2
1,2
3
3
1,2
R. Daza , N. Marí , G. R. Plaza , B. G. Gálvez , A. Bernal , G. V. Guinea , J. Pérez1,2
1,2
Rigueiro , M. Elices
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1
Departamento de Ciencia de Materiales. Universidad Politécnica de Madrid. Madrid 2 Centro de
Tecnología Biomédica. Universidad Politécnica de Madrid. Madrid 3 Departamento de Cardiología
Regenerativa. Centro Nacional de Investigaciones Cardiovasculares. Madrid
Mechanical properties of cells are key and influence their ability to migrate and their
contribution to tissue development and regeneration. The effect of the mechanical cues in cell
fate is particularly important in the case of stem cells [1] and, for them, stiffness could play a
major role in their ability to migrate, which is crucial for tissue regeneration. However, this
behavior has not yet been completely studied. Several methods, including magnetic twisting
cytometry, optical tweezers, and cell indentation, have been used for the study of cell
mechanical properties. Atomic force microscopy (AFM) has become a popular method for
studying the mechanical properties of living cells allowing imaging them and analyzing locally
their mechanical properties when cells are in physiologically relevant environments [2]. In this
work, we have used AFM to carry out the mechanical behavior of cardiac stem cells, analyzing
the relation of the elastic parameters to the region of the adherent cell studied and their
variability. The study of the mechanical properties of these cells is considered important in the
frame of the current works to identify routes to improve their ability to regenerate damaged
cardiac tissue.
[1].
A. J. Engler, S. Sen, H. L. Sweeney and R. D. E. Discher, Cell 126, 677 (2006)
[2]. M. Radmacher, R. W. Tillman, M. Fritz and H. E. Gaub, Science 257, 1900 (1992)
P24
Exploring Van Der Waals Interaction For Organic
Macromolecules On Metal Surfaces
1,2
3
3,4
3,4
Ane Sarasola , Mikel Abadía , Rubén González -Moreno , Celia Rogero , Aran
Garcia-Lekue
1
2,5
2
Departamento de Física Aplicada I UPV/EHU, 48003, Bilbao, Spain Donostia International Physics
3
Center (DIPC), 20018 San Sebastian, Spain Centro de Física de Materiales (CSIC-UPV/EHU), 20018 San
4
Sebastian, Spain Instituto de Ciencia de Materiales de Madrid (CSIC), 28049, Madrid, Spain
5
IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain
A deep understanding of the interaction between the building blocks of an organic/inorganic
interface is key to control the engineering of such nanostructures. For this aim, a reliable
description of the geometry and energy of the system is required. Although Density Functional
Theory (DFT) has widely demonstrated its efficiency to describe the adsorption of organic
molecules on metal surfaces using Generalized Gradient Approximation (GGA) functionals,
recent developments including van der Waals (vdW) non local forces have provided a step
further towards a trustworthy description of organic-molecule metal junctions[1]. Among all
the vdWinclusive DFT schemes considered, vdW-dF (with its optB88 functional) and vdWsurf
are reported to be the most accurate ones [2]. Motivated by recent STM experiments [3], we
have compared the theoretical description of a macromolecule deposited on a reactive
surface, such as phtalocyanines (H2Pc) and metalized phtalocyanines (CuPc) on Cu(110), using
78
GGA and optB88-vdW functionals. On one hand, we have investigated the influence that the
distortion of the molecule and the reconstruction of the surface may have on the binding
energy curves and on the bonding mechanism[4]. On the other hand, we have gained insight
into the interaction between the adsorbed molecule and surrounding extra Cu adatoms, which
are known to be abundant on Cu (110) surfaces[5].
Figure: A) STM image and an illustration of H2Pc molecules adsorbed on Cu(110) surrounded by Cu adatoms. B)
Atomic conﬁguration of the H2Pc molecule on Cu(110). The different adatom adsorption sites considered in the
calculations are represented by white numbered positions.
[1].
A.Tkatchenko, L.Romaner, O.T. Hofmann, E.Zojer, C.Ambrosch-Draxl, M. Scheffler, MRS bulletin
35, 435 (2010)
[2]. J.Carrasco, W.Liu, A.Michaelides, A.Tkatcehnko, J. Chem.Phys. 140, 084704 (2014)
[3]. M.Abadía, R.González-Moreno, A.Sarasola, G.Otero, L. Floreano, A.Garcia-Lekue, C.Rogero, ACS Nano,
submitted (2014)
[4]. P.Sony, P.Puschnig, D. Nabok, C. Ambrosch-Draxl, Phys.Rev.Lett. 99,176401 (2007)
[5]. Matthew S. Dyer, Abel Robin, Sam Haq, Rasmita Raval, Jiří Klimeš, ACS Nano 5, 1831 (2011)
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P25
Moirés on Graphene/Pt(111): low temperature NCAFM
measurements and first-principles calculations
M. Ellner1, B. de la Torre2, P. Pou1,3, N. Nicoara2,4, J. M. Gómez-Rodríguez2,3, R. Pérez1,3
1Dept. Física Teórica Materia Condensada, Universidad Autónoma de Madrid, Spain
2Dept. Física Materia Condensada, Universidad Autónoma de Madrid, Spain
3Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Spain
4Iberian Nanotechnology Laboratory, Braga, Portugal
The epitaxial growth of graphene on metals is currently an active field of research [1].
Graphene on Pt(111) being of utmost interest due to the low interaction of its pristine surface
with the metal resulting in moiré patterns with small topographic corrugation. Whereas the
STM resolves the moirés through its dependence of the DOS [2], the system becomes a
challenging one for the NCAFM and ideal for examining the sensitivity of this technique to local
electronic variations.
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In this work, for the first time, the graphene/Pt(111) system is studied with NCAFM both
experimentally and theoretically. With a home-made AFM operating at 5K and UHV, atomic
resolution, inversion of atomic contrast from a hexagonal to a triangular lattice, and different
moiré patterns are observed. We explain these results with first-principle DFT calculations. The
inversion of atomic contrast may be rationalized in terms of the electronic density dependence
of the Pauli interaction [3]. However, we associate the AFM observation of the moiré to subsurface resolution. The non-topographic corrugation of the moiré is obtained in the repulsive
regime, where the tip indents the graphene sheet deep enough so the displaced carbon atoms
act as a tip that allows sensing the Pt surface with atomic resolution. This idea may be
generalized to other 2D materials opening the door to simultaneous monolayer/substrate AFM
characterization.
[1]. A. J. Martínez-Galera, et al. Nano Lett. 11, 3576 (2011).
[2]. M. M. Ugeda, et al. Phys Rev Lett. 107, 116803 (2011).
[3]. Ondracek et al. Phys Rev Lett, 106, 176101 (2011).
P26
Magnetic Domain Structures In Single Modulated FeCoCu
Nanowires
1
1
1
1
O. Iglesias-Freire , E. Berganza , C. Bran , M. Vazquez , A. Asenjo
1
1
Instituto de Ciencia de Materiales de Madrid, Cantoblanco.
In this work, we present a Magnetic Force Microscopy (MFM) study on the domain
configuration of single FeCo based cylindrical nanowires. FeCo nanowires exhibit the necessary
capability to be employed in novel generation of rare-earth-free permanent magnets due to
their high Curie temperature, large saturation magnetization and enhanced magnetic hardness
[1]. High resolution MFM technique has been used to characterize isolated nanowires
deposited onto Si substrates. The polycrystalline Fe28Co67Cu5 nanowires, growth by
electrochemical methods into the anodic alumina membrane, present high shape anisotropy
due to their high aspect ratio. Tailoring the membrane pore diameter we can prepare straight
nanowires, as well as modulated nanowires with diameter varying periodically between 22 nm
and 35 nm. MFM imaging allows us to conclude that the straight nanowires posse a dominant
80
single domain behaviour even in the demagnetized state, while modulated ones -with
increased hardness- show the presence of domain walls. Micromagnetic simulations [2] predict
the magnetization to point along the wire main axis in both cases although two kinds of stable
domain walls are expected for the modulated wires.
[1]. Bran et al., “Structural Dependence of Magnetic Properties in Co-Based Nanowires: Experiments and
Micromagnetic Simulations,” IEEE Trans. Magn., vol. 49, no. 8, p. 4991,2013
[2]. OOMM, M. J. Donahue and D. G. Porter, National Technical Information Service Document No. PB99163214, National Institute of Standards and Technology (NIST), September 1999
P27
Donor-acceptor Interactions At Solid Surfaces Controlled By
Charge Transfer
1
2
3
3
1,3
Koen Lauwaet , J. Rodríguez-Fernández , R. García , M. A. Herranz , N. Martín , J. M.
1,4
1,2
Gallego , R. Otero , R. Miranda
1
1,2
IMDEA-Nanociencia. Madrid. 2 Universidad Autónoma de Madrid. Madrid. 3 Universidad Complutense
de Madrid. Madrid. 4 ICMM-CSIC. Madrid.
Organic charge-transfer (CT) complexes are molecular compounds mixing two species with
different electron affinities: an electron donor (D) and an electron acceptor (A). Charge
transfer processes between D–A complexes and metallic electrodes are at the heart of novel
organic optoelectronic devices such as solar cells [1]. In contrast with the existing exhaustive
study of the bulk properties of CT solids, very little is known about the thinfilm behaviour. The
transition from bulk D-A complexes to ultra-thin films of monolayer thickness deposited on
metals introduces a new phenomenology related to the organic– inorganic interface [2].
Effects like hybridization, CT with the surface and molecular level alignment become factors
that may govern the electronic transport. Hence, the adsorption of an ultra-thin D–A layer on a
metal opens a new field of research for the potential application of CT complexes as devices in
the nanoscale. Simultaneous characterization of the interdependent structural and electronic
properties is required for a thorough understanding of the D-A complexes under study [3].
Here, by combining both Scanning Tunnelling Microscopy (STM) and X-ray Photoelectron
Spectroscopy (XPS) in situ, we can study the delicate balance that exists between
intermolecular and molecule–substrate interactions, as well as the hybridization, and the
charge transfer taking place in model donor–acceptor assemblies at metal-organic interfaces.
By controlling the stoichiometry between tetrathiafulvalene (TTF, electron-donor) and
tetracyanoethylene (TCNE, electronacceptor), we can tune both the structural and the
electronic properties of a donor-acceptor system on Ag(111). We show that this system
exhibits various structural phases, depending on the stoichiometry, each leading to different
levels of charge transfer. Interestingly enough, the charge-transfer does not seem to follow a
monotonic behavior with the D:A ratio. These results demonstrate that atomistic studies on
the growth of organic thin films under ultrahigh vacuum (UHV) conditions can lead to the kind
of accurate control needed in order to optimize device characteristics.
[1]. L. Bartels, Nat. Chem., 2, 87 (2010).
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[2]. N. Gonzalez-Lakunza, I. Fernández-Torrente, K. J. Franke, N. Lorente, A. Arnau, and J. I. Pascual, Phys. Rev.
Lett., 100, 156805 (2008)
[3]. D. G. de Oteyza, J. M. Garcıá-Lastra, M. Corso, B. P. Doyle, L. Floreano, A. Morgante, Y. Wakayama, A.
Rubio, and J. Enrique Ortega, Adv. Funct. Mater., 19, 3567 (2009)
P28
Local Electrical Properties Of Double Terminated
La0.7Sr0.3MnO3 Films
1
1
1
1
1
Laura López-Mir , José Cisneros , Carmen Ocal , Lluís Balcells , Benjamín Martínez ,
Laura López-Mir
1
1
Institut de Ciència de Materials de Barcelona, ICMAB‐CSIC, Campus UAB, 08193 Bellaterra, Spain
La0.7Sr0.3MnO3 (LSMO) thin films were grown using sputtering technique onto STO substrates
initially exhibiting either SrO or TiO2 single chemical termination or a mixture of both. A
combination of tapping mode atomic force microscopy (AFM) and conductive AFM (CS-AFM)
has been used to study the topography and the electric properties of the films. Though the
deposited films are expected to grow following the stacking sequence of the substrate [1], all
obtained LSMO films presented bimodal conducting properties typical of double terminated
films, therefore indicating that the substrate termination has not been replicated at the thin
film surface in our case. The possible influence of surface termination on the electrical
properties of the films and the local induced resistive switching [2] using the AFM tip as top
electrode has been explored. Finally, as resistive switching is crucially dependent on the
electrode-film interface; several AFM probes with different conductive coatings have been
used to study the influence of the current sensing tool in this phenomenon
P29
The Mode Of Growth And Magnetic Properties Of Ultrathin
Co Films Grown On The Curved Pd(111) And Curved Ni(111)
1
2
3
1,2,3
A. Magaña , M. Ilyn , L. Fernández , J. E. Ortega
1
, F. Schiller
2
Departamento de Fisica Aplicada I, Universidad del Pais Vasco, E-20018 Donostia-San Sebastian, Spain 2
Centro de Fisica de Materiales (CSIC-UPV-EHU) and Materials Physics Center (MPC), E-20018 DonostiaSan Sebastian, Spain 3 Donostia International Physics Center, E-20018 Donostia-San Sebastian, Spain
Ultrathin Co films grown epitaxially on Pd(111) and Ni(111) demonstrate out-of-plane (OOP)
magnetic anisotropy due to the strong interfacial effects. These materials were found to be
useful for applications in spin-torque devices and bit-patterned magnetic media. Furthermore
it is a suitable playground to study the interplay between the crystal structure, electronic and
magnetic properties of the interfaces [1]. Though the mode of growth and magnetism of Co
films have been thoroughly studied for flat Pd(111) and Ni(111), these properties are less
investigated when the substrate is comprised by vicinal surfaces of these single crystals.
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Meanwhile stepped reconstructions of the vicinal surfaces alter the surface electronic states of
the substrate and substantially affect the mode of growth of the overlayers. Also they were
found to be a useful template for growth of the ordered nanostructures [2,3].
In this work we present results of study of the mode of growth and magnetic properties of the
ultrathin Co films grown on the curved Pd(111) and curved Ni(111). We have used two large
single crystals (9x9 mm2 and 12x12 mm2 respectively) polished so that the miscut angle
toward the [112 ̅] or [1 ̅1 ̅ 2] direction changes smoothly from 0 to 11 and from 0 to 15
degrees, respectively. Since the width of the terrace of the reconstructed surface depends on
the miscut angle it has allowed us to study the growth mode as a function of the terrace’s
width in the range from 100 to 1 nm, and a Co coverage from submonolayer to few
monolayers
Combined STM and LEED measurements at room temperature yielded systematic data on the
variation of the structure and morphology of the Co films with miscut angle. In-situ MOKE
measurements performed at room temperature and at 130 K complemented it with
information about the magnetic anisotropy. Using of the substrates with relatively big (9% for
Pd(111)) and small (2% for Ni(111)) lattice mismatch revealed the effect of the strain.
P
[1]. M. T. Johnson, P. J. H. Bloemenz, F. J. A. den Broeder, J. J. de Vries, Rep. Prog. Phys. 59, 1409 (1996)
[2]. A. Mugarza, F. Schiller, J. Kuntze, J. Cordon, M Ruiz-Oses, J. E. Ortega, J. Phys.: Condens. Matter 18, S27
(2006)
[3]. K. Kuhnke and K. Kern J. Phys.: Condens. Matter 15 (2003) S3311–S3335
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Neural Signatures Protocol In Artificial Neural Networks Used
To Characterize The Electrostatic Signal In Conductive Thin
Films
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1
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Elena Castellano-Hernández , Juan José Sáenz Gutiérrez , Sacha Gómez
1
1
Universidad Autónoma de Madrid. Spain
The use of scanning probe microscopy (SPM) to characterize and manipulate surfaces at the
nanoscale usually faces the problem of dealing with systems where several parameters are not
known. Artificial neural networks (ANNs) have demonstrated to be a very useful tool to tackle
this type of problems. Here, we show that the use of ANNs allows us to quantitatively estimate
magnitudes such as the dielectric constant of thin films or the amount of free charge that is
present in the sample. To improve thin film dielectric constant estimations in EFM, we first
increase the accuracy of numerical simulations by replacing the standard minimization
technique by a method based on ANN learning algorithms. Second, we use the improved
numerical results to build a complete training set for a new ANN. The results obtained by the
ANN suggest that accurate values for the thin film dielectric constant can only be estimated if
the thin film thickness and sample dielectric constant are known. Moreover, we demonstrate
that the presence of free charge (i.e. A non-zero value for the conductivity) can change
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dramatically the response of the microscope, making this fact a very important issue to take
into account when quantitative values are being measured.
To get a deeper knowledge of the physical processes involved in the imaging of thin films by
Scanning Probe Microscopy we use artificial neural networks to replace the full structure of a
thin film over a dielectric substrate by an equivalent semiinfinite sample described only by an
effective dielectric constant. For thin film thicknesses around 1 nm, we demonstrate that thin
film dielectric constants between 1000 and 10 000 give very different electric responses. This
effect is of great interest in the study of thin materials with a high polarizability such as
graphene layers, where we find that for electrostatic purposes, a graphene layer is equivalent
to an extremely thin dielectric layer with an effective permittivity that depends on the
conductivity of the layer and spans from 5 for the insulating layers, to 2000 for the more
conductive ones. ANN techniques such as neural signatures are used to improve the
knowledge of the most relevant elements inside the EFM signal.
P31
Towards An AFM Study Of The Interaction Of Pseudomonas
Aeruginosa With Multivalent Glycoclusters
1
1
2
1
2
3
4
F. Zuttion , D. Sicard , C. Ligeour , Y. Chevolot , F. Morvan , A. Imberty , G. Vergoten ,
5
2
1
1
S. Vidal , J.J. Vasseur , E. Souteyrand , M. Phaner-Goutorbe
1
de Lyon, 36 avenue Guy de Collongue, 69134 Ecully, France 2 Institut des Biomolécules Max Mousseron,
Département des Analogues et Constituants des Acides Nucléiques (DACAN), UMR 5247 CNRS-UM1UM2, Université de Montpellier 2, CC1704, Place E. Bataillon 34095 Montpellier Cedex 5, France 3
CERMAV (CNRS, UPR 5301), Universitè Joseph Fourier, BP53, Grenoble, France 4 Laboratoire de
Glycobiologie Structurale et Fonctionnelle, (LGSF) UMR CNRS-Universitè de Lille 1, Cité scientifiqueBâtiment SN3, 59655 Villeneuve d’Ascq Cedex, France 5 Université de Lyon, Institut de Chimie et
Biochimie Moléculaires et Supramoléculaires (ICBMS, UMR CNRS 5246), Laboratoire de Chimie
Organique 2- Glycochimie, 43 boulevard du 11 Novembre 1918, 69622 Villeurbanne, France
Pseudomonas aeruginosa (PA) is one of the most common pathogen identified in respiratory
track infections of fibrosis cystic patients [1]. It takes advantage of different molecular tools
(virulence factors) to adapt and proliferate in the human lugs. A promising approach is to
inhibit the virulence factors of PA and particularly two lectins PA-IL and PA-IIL to develop a new
antibacterial therapeutic approach. Here, we present our results in which we focused on the
interaction of the galactose specific tetrameric lectin PA-IL
[2] and tetrameric galactose molecules (galactococlusters) as possible inhibitors of PAIL’s
activity in the infection process. We have used Atomic Force Microscopy (AFM) technique in
order to investigate the molecular arrangement of the complexes formed by PA-IL and
different galactoclusters, and we have demonstrated that the organization of the complex
depends on the topology of the glycocluster and on the hydrophobic/hydrophilic behavior of
the glycoside moiety [3]. Also Single-Molecule Force Spectroscopy experiments are ongoing
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and our preliminary results related to the characterization of the adhesion force between a
functionalized AFM tip -at which the lectin is attached- and glycoconjugates anchored to silica
surface via DNA Direct Immobilization [1], [4] will be discussed.
[1].
A. Goudot, G. Pourceau, A. Meyer, T. Gehin, S. Vidal, J.-J. Vasseur, F. Morvan, E. Souteyrand, and
Y. Chevolot, Biosens. Bioelectron., vol. 40, no. 1, pp. 153–60, Feb. 2013.
[2]. G. Cioci, E. P. Mitchell, C. Gautier, M. Wimmerová, D. Sudakevitz, S. Pérez, N. Gilboa-Garber, and A.
Imberty, FEBS Lett., vol. 555, no. 2, pp. 297–301, Dec. 2003.
[3]. D. Sicard, Y. Chevolot, E. Souteyrand, a Imberty, S. Vidal, and M. Phaner-Goutorbe, J. Mol. Recognit., vol.
26, no. 12, pp. 694–9, Dec. 2013.
[4]. M. Phaner-Goutorbe, V. Dugas, Y. Chevolot, and E. Souteyrand, Mater. Sci. Eng. C, vol. 31, no. 2, pp. 384–
390, Mar. 2011.
This work was financially supported by ANR-12-BSV5-0020, Lyon Biopole. Plateform NanoLyon is
acknowledged for its technical support
P32
Surface Characterization Of PEGylated Self-assembled
Monolayers On Gold For Biosensors Applications
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1
A. Garnier , F. Zuttion , F. Palazon , Y. Chevolot , E. Laurenceau , G. Grenet , C.
1
1
Botella , E. Souteyrand , M. Phaner-Goutorbe
1
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1
S
de Lyon, 36 avenue Guy de Collongue, 69134 Ecully, France
T
The health and agrifood sectors are now pushing the limits of instrumentation and are
demanding fast analysis of multiple samples in real-time. Currently, the detection,
quantification and characterization of low-concentration biomolecules in complex fluids
(human plasma or food samples) require many preparation steps and cannot be done in realtime. Thanks to the development of new techniques such as Surface Plasmon Resonance
Imaging (SPRI) or Surface-Enhanced Raman Spectroscopy (SERS) it is possible to attain these
performances, since both are label-free and real-time detection methods. Nevertheless, these
techniques require the providing of well adapted bioreceptors in order to obtain reproducible
and reliable analysis. In our group, we fabricate these bioreceptors by taking advantage of the
affinity of gold with thiols: thus, gold surfaces are functionalized with self-assembled
monolayers (SAMs) in order to subsequently immobilize the biological probe able to
specifically recognize the target compounds [1]. We tested different kinds of molecules to
form the SAMs; in general they are constituted of a thiol group -that allows a covalent binding
to the gold surface-, an alkyl-chain followed by a polyethylene glycol (PEG) chain of variable
length and a head group that determines the hydrophobic/ hydrophilic nature of the SAM. In
particular, we focused our attention on two head groups: the carboxyl group (COOH) and the
methoxy group (OMe), since the former can be chemically activated in order to covalently
graft the biological probe of interest and the latter can be used to avoid the non specific
adsorption [2]. To improve the performances of bioreceptors, it is critical to ensure at each
step that the chemical functionalization process leads to a well organized SAM. So, the
morphological and chemical aspects of these surfaces have to be investigated both at micro
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and nano scales before grafting biomolecules. To do that, we used complementary methods
such as X-ray Photoelectron Spectroscopy (XPS), Polarization Modulation-Infrared Reflection
Adsorption Spectroscopy (PM-IRRAS), contact angle and Atomic Force Microscopy (AFM).
Among all these techniques, only the AFM allows us to analyze the samples at the nanoscale.
Herein we present a set of results on the characterization and comparison of various SAMs on
gold. In particular, the AFM investigation has allowed us to get into the homogeneity and the
adhesion properties of the samples.
[1]. M. Veiseh, B.T. Wickes, D.G. Castner, M. Zhang Biomaterials 25 (2004) 3315-3324.
[2]. J. Lahiri, L. Isaacs, J. Tien, G.M. Whitesides, Anal. Chem. 71 (1999) 777790.
[3]. The ANR P2N (ANR-12-NANO-0016-04 - PIRANEX project) is greatly acknowledged for financial support;
CNANO Rhône-Alpes for PM-IRRAS funding; NanoLyon for providing gold samples
P33
Sublattice localized electronic states in atomically resolved
graphene-Pt(111) edge-boundaries
P. Merino1, L. Rodrigo2, A. L. Pinardi3, J. Méndez3, M. F. López3, P. Pou2, R. Pérez2, J. A.
Martín-Gago1,3
1
Centro de Astrobiología INTA-CSIC, Madrid, Spain.
2
Dpto. de Física Teórica de la Materia Condensada and IFIMAC, UAM, Madrid, Spain.
3
Instituto de Ciencias de Materiales de Madrid, CSIC, Madrid, Spain.
Understanding the connection of graphene with metal surfaces [1] is a necessary step for
developing atomically-precise graphene-based technology. In this work [2] we combine high
resolution RT-STM experiments with DFT calculations and non-equilibrium Green's functions
method to unveil the atomic structure of a border-like edge between a Pt(111) step and a
graphene zigzag edge. We have managed to get atomic resolution not only on both the metal
and the graphene but also on the boundary (see Fig. 1). The graphene edges minimize their
strain by inducing a 3-fold edge-reconstruction on the metal side. The tendency to form
passivated zigzag graphene terminations plays a relevant role in the formation and orientation
of the stable Moiré patterns. Our combined approach reveals the interesting electronic
properties of this nanoscopic system including the preservation of the G-edge state shifted to
energies at about +0.8 eV above Fermi level, highly localized in one of the graphene sublattices
and confined to the G-Pt interface. This state spreads out inside the first Pt row resulting in a
high quality G-metal electric contact that could be relevant for designing future atomically
precise graphene metal leads [3].
86
Fig. 1 A) Experimental RT-STM image of a graphene flake on a Pt(111) step edge. B) Atomic structure of
graphene zigzag edge on a Pt step calculated by a DFT method based on VASP. C) STM image compared
with the atomic structure calculated with DFT. D) Simulated STM profiles at constant height (2.75 Å) for
different bias voltages.
[1]. P. Sutter et al, PRB, 80, 245411 (2009); Martínez-Galera et al., Nano Lett., 11, 3576 (2011).
[2]. P. Merino, L. Rodrigo et al. Accepted in ACS Nano (DOI: 10.1021/nn500105a).
P34
Quantum Capacitance and Electromigration: A Theoretical
Approach
P
O
C. Salgado 1, J.J. Palacios 1
S
1
Universidad Autónoma de Madrid, Dep. Condensed Matter Physics, Madrid, Spain
In recent years electron transport through metallic contacts at the nanoscale has been studied
theoretically and with experiments. The most studied quantity is the current along with its
derivatives. However, this is not the only quantity that can be measured. Capacitance also
gives valuable information about the electronic and structural properties of the nanocontacts.
We are interested here in the Quantum Capacitance which depends on the density of states
and measures the quantum contribution to the capability of a device to accumulate electrons.
This quantity depends of the chemical nature, i.e., of the available atomic levels of the
material. It also depends of the energy with which electrons are injected. Therefore, it has a
quantum mechanical origin in contrast to the purely electrostatic one [1].
We used ab-initio calculations based on DFT methods and the Nonequilibrium Green's
Function Formalism to simulate such systems. To introduce non-equilibrium conditions, we
apply an external bias voltage, at which electrons are injected. Among the simulated systems,
there are contacts from different metals. Non-voltage-symmetric charge distributions emerge
of our calculations. This is a result of the absence of electron-hole symmetry. The distinctive
DOS corresponding to each metal is determinant in the capacitance, as well as other transport
properties.
Simulation of Gold atom electromigration between two contacts under applied bias
voltage.
Chemisorption
of H on
Graphene.
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We also studied how the charge distribution affects the nonequilibrium induced forces on the
atoms. This allows us to explain the transfer of atoms between the metallic electrodes
mediated by the bias voltage. This phenomenon is called electromigration. If an atom moves
between the two biased contacts, there arise forces occurring on the atom. These appear due
to the nonequilibrium charge distribution[2] . The free energy that describes an out of balance
problem, loses the symmetry corresponding to equilibrium. This leads forces that can
determine a preferred direction for the electromigration of the atoms.
The same procedure is used to investigate the behavior of other systems under nonequilibrium conditions. This is the case of hydrogen chemisorption on grapheme [3]. Recent
STM-experiments show how the sign and the value of the applied voltage in the tip can tune
whether chemisorption occurs or not.
[1]. S. Datta, Quantum Transport: Atom to transistor, (2005) 3932.
[2]. T. Todorov, D. Dundas, Physical Review B 81, (2010) 075416.
[3]. D.W. Boukhvalov, MI. Katsnelson, Physical Review B 77(3), (2008), 035427.
I would like to thank to my advisor, Juan José Palacios, for his advice and for guiding me through the research.
I also would like to thank to Julio Gómez-Herrero, Elsa Prada and María Soriano, from the Universidad
Autónoma de Madrid, and Carlos Untiedt, María José Caturla and Bernat Oliver, from the Universidad de
Alicante, for their collaboration and support.
P35
Domain overlap in Ni/Cu/Ni films with perpendicular
magnetization: role of defects and ferromagnetic coupling
Miguel Ciria1,2, Edna Corredor1,2, David Coffey1,2, José Luis Diez-Ferrez3 and José Ignacio
Arnaudas 2,3
1
Instituto de Ciencia y Materiales de Aragón CSIC-Universidad de Zaragoza, Zaragoza,
2
Spain Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza,
3
Spain. Laboratorio de Microscopias Avanzadas, Universidad de Zaragoza, Zaragoza, Spain.
Magnetostatatic interaction between layers with perpendicular magnetization induces parallel
alignment between the domains of each block unless an antiferromagnetic AF coupling exists
between the blocks [1]. Here we show, by performing magnetic force microscopy images on
Ni(tNi)/Cu(3 nm)/Ni(tNi) structures, with tNi = 3 and 4 nm, that a large area of the structure
with tNi = 3 nm has an antiparallel (AP) domain configuration without the presence of AF
coupling, and that the area of these unexpected structure decreases for tNi = 4 nm, see Figure.
The energy Em of the magnetic configurations is obtained by calculating the magnetostatic
energy for periodic domain configurations with only parallel (P) domains, and for
configurations with parallel and antiparallel (P-AP) domains, as well as the domain wall density
energy. Em is calculated numerically showing that the P domain configuration has the lowest
energy. Nevertheless the energy difference between the P and the P-AP configuration, Em,
for the Ni(3 nm)/Cu(3 nm)/Ni(3 nm), about 600 J/m3 is three times smaller than the value
calculated for the Ni(4 nm)/Cu(3 nm)/Ni(4 nm) sandwich, about 2000 J/m3. We propose that
the pinning of the domain walls by defects, such as threading dislocations, is able of stabilize
the AP configuration in the Ni(3 nm)/Cu(3 nm)/Ni(3 nm) structure but fails to create the same
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configuration as tNi increases because, beside the increment of Em,, the shape of the
minimum of Em as a function of the domain size changes from a shallow feature to a deep and
well defined shape, leading to an increased domain size [2].
Figure. Magnetic force microscope image of a 4 nm thick nickel film (a), the Ni(3 nm)/Cu(3 nm)/Ni(3 nm) (b) and
the Ni(4 nm)/Cu(3 nm)/Ni(4 nm) (c) structures.
[1]. N. S. Kiselev, I. E. Dragunov, U. K. Rößler, and A. N. Bogdanov, Appl. Phys Lett 91, 132507 (2007)
[2]. G. Bochi et al. Phys Rev. Lett. 75, 1839 (1995)
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P36
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Characterization Of Trimethylamonium-based Ionic Liquid
Surfaces With Scanning Force Microscopy
1
1
2
Jaime Colchero , Jesús Sánchez-Lacasa , Pedro Lozano , Juana M. Bernal
1
S
T
2
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Departamento de Física, Instituto Universitario de Investigación en Óptica y Nanofísica (IUIOyN),
Universidad de Murcia 2 Departamento de Bioquímica y Biología Molecular B e Inmunología, Facultad de
Química, Universidad de Murcia
S
The objective of this work is to investigate the superficial structure of an ionic liquid family
widely used in various fields of science to better understand the unique properties of these
molten salts and their modern applications: energy storage devices, lubricants or solvents for
nanoparticle stabilization, materials extraction or reactive catalytic supports among other uses.
For this study we have used hydrophobic ionic liquids (ILs) based on trimethylamonium cations
with long alkyl side-chains, [Cntma][Ntf2], with n=12, 14, 16 and 18, on top of a metallic
substrate. For the nano-characterization of the surfaces we have used a Scanning Force
Microscope working in the dynamic mode, finding large flat planes of nanometer thickness for
all samples prepared indication nanocrystalline ordering . Thickness dependence with alkyl
side-chain length has been also studied in detail in these compounds. When these ILs are
deposited on a structured substrate (e.g. the metallic covering of a DVD) they fill up the tracks
on the DVD and grow above them without flooding the available surface. The upper surface of
these IL walls stay flat and exhibit a rich dynamics as shown in the pictures.
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P37
Manipulation Of The Electronic Structure In A Ruthenium
Complex By An STM/AFM Tip
1
2,3
4,5
Marten Piantek , David Serrate , Jose Ignacio Pascual , Ricardo Ibarra
1
2,3
Instituto de Ciencia de Materiales de Aragón - ICMA-CSIC, Universidad de Zaragoza 2 Laboratorio de
Microscopías Avanzadas - LMA, Universidad de Zaragoza 3 Departamento de Física de la Materia
Condensada, Facultad de Ciencias, Universidad de Zaragoza 4 IKERBASQUE, Basque Foundation for
Science, Bilbao 5 CIC NanoGUNE, Donostia-San Sebastian
Metal- organic complexes are of high interest in a wide range of material science due to their
magnetic properties. The electronic configuration of the metallic center that usually defines
the magnetic state of the molecule strongly depends on the electric field induced by the
coordinating ligands. Instead of axial molecular ligands we used the tip of an STM/ AFM sensor
in order to manipulate the electronic structure of the metallic center of a squared-planar
Ru(dibenzoylmethanate)2 complex. With force-distance measurements we traced the
interaction pathway between the Ru ion and the tip, and found a discrete jump into contact.
Scanning tunneling spectroscopy revealed a change of the density of states around the Fermi
level and hence in the electronic configuration of the Ru ion after contact formation.
P38
Temperature Controlled Formation Of Metal-organic
Assemblies On Surfaces
1
2,3
4,5
Marten Piantek , David Serrate , Jose Ignacio Pascual , Ricardo Ibarra
1
2,3
Instituto de Ciencia de Materiales de Aragón - ICMA-CSIC, Universidad de Zaragoza 2 Laboratorio de
Microscopías Avanzadas - LMA, Universidad de Zaragoza 3 Departamento de Física de la Materia
Condensada, Facultad de Ciencias, Universidad de Zaragoza 4 IKERBASQUE, Basque Foundation for
Science, Bilbao 5 CIC NanoGUNE, Donostia-San Sebastian
On-surface chemical synthesis of organic species is a rapidly emerging tool in surface science
for the in-situ creation of large organic compounds that cannot be produced in any other kind
chemical synthesis. The demand for such materials is for example reflected by the effort that is
being made on the development of extended metal-organic covalent networks as future
materials in information technology. A recent approach in this direction, using so called
steering reactions, starts from well ordered chemical templates in form of coordination
networks [1]. By thermal activation the coordinative character of the network transforms into
covalent while the network´s structural order persists. Chemical templates are only suitable if
they are structurally stable at the activation temperature. For the development of suitable
syntheses strategies a detailed understanding of the annealing process is hence inevitable. We
followed the route of Abel et al. [2] and used a transition metal and the organic ligand
Tetracyanobenzene (MnTCNB) as precursors for the metal-organic network. An extended
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temperature-dependent study of Mn-MnTCNB coordination networks on different substrates
in view on their suitability as chemical templates was conducted. By means of variable
temperature STM we monitored transitions between several apparent and occasionally exotic
network phases in a range between room temperature and 400 °C. The substrate turned out
to play a crucial role since at elevated temperatures the surface reactivity increases and hence
the influence on the network´s integrity. Hence the chemical templates available for the
covalent reaction and the resulting covalent compounds depend strongly on the choice of the
substrate.
[1]. Lin, T.; Shang, X. S.; Adisoejoso, J.; Liu, P. N.; Lin, N. Journal of the American Chemical Society 2013, 135,
3576–3582.
[2]. M. Abel, S. Clair, O. Ourdjini, M. Mossoyan, and L. Porte, J. Am. Chem. Soc., 133, 1203 (2011). “Single
Layer of Polymeric Fe-Phthalocyanine: An Organometallic Sheet on Metal and Thin Insulating Film”
P39
The Verge Of Antiferromagnetic RKKY Order Among
Individual Kondo Impurities
1
2
1
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1,3
María Moro-Lagares , Marten Piantek , M. Ricardo Ibarra , José I. Pascual , David
O
1
Serrate
1
INA-LMA, University of Zaragoza, Spain 2 ICMA, CSIC-University of Zaragoza, Spain 3 CIC-Nanogune,
S
Donostia-San Sebastián, Spain
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The Ruderman-Kittel-Kasuya-Yosida interaction (RKKY) is the paradigm to build artificial spin
systems with controllable coupling for applications in quantum and classical information
processing. The control and read-out of the spin state in such devices by electric means entails
necessarily contacting individual localized spins with metallic leads. In virtue of the
antiferromagnetic exchange coupling with the lead conduction electrons, the localized spin is
prone to become a Kondo screened spin-singlet, losing thereby its functionality. Thus, Kondo
screening and RKKY mediated magnetic coupling of spins are mutually exclusive. Using a
scanning tunneling microscope, we studied the phase transition between both regimes by
performing spatially and energy resolved measurements of the Kondo resonance in artificial Co
atomic structures over Ag(111). Our experiments demonstrate the coexistence of Kondo
screening and RKKY correlations of localized 3d magnetic moments. Magnetic correlations are
already noticeable for atoms 14.5 Å apart as a decrease of the Kondo resonance amplitude. At
interatomic separations of 5.8 Å, the impurity spin becomes delocalized and an effective
antiferromagnetic RKKY interaction of 2 meV arises. In order to suppress Kondo fluctuations in
favor of magnetic order we have built Co clusters with controlled geometry and interatomic
separation. We find a systematic splitting and vanishing of the Kondo resonance which
depends on the magnetic ground state of each cluster in the absence of Kondo screening.
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P40
Substrate/nanodot Exchange Coupling For Co Nanodot Arrays
Grown On Rare Earth–Au (111) Based Nanotemplates
1
1,2
3
2,4
6
1,3
1,3
1
L. Fernández , M. Blanco-Rey , M. Ilyn , L. Vitali , A. Magaña , A. Correa , P.
5
1,3,6
Ohresser , J.E. Ortega , A. Ayuela , F. Schiller
1
Donostia International Physics Center, 20018 Donostia-San Sebastián, Spain 2 Departamento de Física
de Materiales, Universidad del País Vasco UPV/EHU, 20018 Donostia-San Sebastián, Spain 3 Centro de
Física de Materiales (CSIC-UPV-EHU) and Materials Physics Center (MPC), 20018 San Sebastián, Spain 4
Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Spain 5 Synchrotron SOLEIL,Saint-Aubin BP 48,
91192 Gif-sur-Yvette, France 6 Departamento de Física Aplicada I, Universidad del País Vasco UPV/EHU,
20018 Donostia-san Sebastián
Controlling and manipulating exchange coupling and anisotropy in patterned magnetic
nanostructures is the key for developing advanced magnetic storage and spintronic devices.
Scanning tunneling microscopy analysis of different rare earth (RE)-Au (111) surfaces reveals
the formation of a trigon network that transforms with longer evaporation times into a RE-Au2
surface alloy with 1-2 ML of thickness. Both structures are found to provide optimal nucleation
points for the formation of hexagonal arrays of Co nanodots. In the case of Gd as RE, X-ray
magnetic circular dichroism measurements reveal an antiferromagnetic coupling across the
Co/nanotemplate interface. In the particular case of the GdAu2 surface it is found that the
coupling is very strong, which is corroborated by full-potential linearized augmented plane
wave calculations. These studies find that the anisotropy of the Co nanodots is profoundly
modified by the influence of the GdAu2 nanotemplate that induces large anisotropy values. In
clear contrast with non-magnetic Au substrates, GdAu2 triggers the early switch in the
anisotropy direction from out-of-plane in monolayer-thick Co, to in-plane, in bilayer Co films.
P41
Ultra High Vacuum PVD Graphene growth on Cu-foils from a
C60 carbon source: growth and characterization
J. Azpeitia1, G. Otero-Irureta2, F. J. Mompeán1, B. Sánchez1, M. García-Hernández1, J. A.
Martín-Gago1, C. Munuera1, M. F. López1
1
Instituto ciencia de Materiales de Madrid-CSIC, Madrid, Spain
2
Universidad de Aveiro, Portugal,
The production of high-quality inexpensive graphene is an absolutely necessary first step for
the material to ever live up to its promise in commercial applications. Among the different
growth methods reported to date, physical vapor deposition (PVD) from a suitable organic
precursor emerges as an advantageous procedure since lower substrate temperatures are
required to produce graphene [1-2]. On the other hand, particularly attractive is the use of low
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carbon solubility Cu substrates for graphene growth, owing to its inexpensiveness and the
possibility of post-growth graphene transfer on arbitrary substrates [3].
In this work, we present the growth of graphene layers by PVD under ultra-high vacuum
conditions on polycrystalline 25 μm oxygen-free Cu foils. We used as carbon source a C60
evaporator maintained at 500 ºC. Prior to carbon evaporation the Cu foils have been treated
by Ar-sputtering and thermal annealing cycles in order to clean them and promote the growth
of well oriented large Cu terraces, especially suitable for LEED analysis (figure 1). After
graphene growth is complete, sample analysis is performed with different techniques to
characterize the structure and quality of the graphene layer. In-situ LEED images show well
defined Cu (111) and (100) reflections and rings corresponding to graphene in various
orientations with respect to the Cu grains (figure 1). Ex- situ Atomic Force Microscopy (AFM)
and Raman spectroscopy are employed to gather information on sample morphology and
quality (figure 1). We are currently optimizing graphene transfer from our samples to
insulating oxide substrates with aim to determine its bandgap and macroscopic and local
magnetotransport properties.
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Figure 1: (a) AFM topographic image of a Cu foil substrate before and (b) after cleaning treatments and graphene
deposition. (c) LEED image of as-grown graphene on Cu-foil showing a (111) domain grain measured with 100 eV.
(d) Raman spectra of graphene covered Cu foil.
[1]. X. Li et al, Science 324, 1312 (2009)
[2]. R. Hawaldar, et al, Sci. Rep. 2, 682 (2012)
[3]. S. Bae et al, Nat. Nanotechnol. 5, 574 (2010)
P42
Unusual Surface Faceting Induce by Metal Organic Complexes
M. Abadia1, R. González-Moreno 1, A. Sarasola 1,2, G. Otero 3, A. Verdini4, L. Floreano 4,
A. Garcia-Lekue 1,5, and C. Rogero 1
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1
2
Centro de Física de Materiales (CSIC-UPV/EHU) and DIPC, E-20018 San Sebastian, Spain Departamento
3
de Física Aplicada I UPV/EHU, 48003, Bilbao, Spain Instituto de Ciencia de Materiales de Madrid (CSIC),
4
28049, Madrid, Spain Istituto Officina dei Materiali (CNR-IOM), Laboratorio TASC,Trieste,
5
Italy Ikerbasque; Basque Foundation for Science; E- 48011; Bilbao; Spain
The actual demand of increasingly smaller devices drives the endeavors to explore new
methods to miniaturize the designs. Thus, the development of methods capable of producing
ordered nanostructured surfaces is a stimulating field.
In this context, a novedous molecular/substrate interaction mechanism that derives in a
unique adsorbate induce surface reconstruction is presented. In particular we show how
metalated phthalocyanines can promote the formation of regular arrays of Cu nanoribbons on
its (110) surface.
At variance with the conventional changes of metal reconstructions upon molecular
adsorption observed so far, the presented faceting is found to involve a massive reorganization
of Cu adatoms. Thus, the energy gain of the final system comes not only
from the
preferential adsorption position of phthalocyanines on the copper surface, but also from their
interaction with the sourrounded adatoms.
By combining experimental (Scanning Tunneling Microcopy) and theoretical surface science
techniques we demostrate that indeed the mechanism behind the massive surface reshaping
involves a molecular mediated uni-directional blocking of diffusing surface adatoms followed
by their capture and accumulation.
[1]. M. Abadia, R. González-Moreno , A. Sarasola , G. Otero , A. Verdini, L. Floreano , A. Garcia-Lekue , and C.
Rogero, ACS Nano. (2014) SUBMITTED
P43
Search For A Gap-less Dangling Bond Wire.
1
1
2
Mads Engelund , Daniel Sanchez-Portál , Thomas Frederiksen , Aran Garcia-Lekué
1
2
2
Centro de Física de Materiales, , Donostia - San Sebastián Donostia International Physics Center,
Donostia-San Sebastián
94
STM induced hydrogen desorption is a method for making patterns with atomic precision on
the Si (001):H and Ge(001):H surfaces. This technique can open pathways for surface electronic
devices controlled with atomic precision. The dangling bond defects on the surface can be
used as templates for further processing steps, e.g., attaching molecules to form a molecular
wire. Still, it would be desirable to largely avoid these extra steps and use exclusively the
dangling bonds for fabricating flat nanometer scale devices. However, the 1D structures
formed by dangling bonds are prone to suffer from instabilities that open a band gap in the
wires.
We have theoretically investigated dangling bond structures on Si(001):H and Ge(001):H with
the aim of finding a ballistically conducting wire without a band-gap. Different levels of doping
have been explored to see if the Fermi level can be manipulated without fundamentally
changing the electronic structure of the wires, thus allowing to move the Fermi level away
from the gap. Our conclusion is that such an approach is possible for Ge, while for Si the wire
electrons have a strong tendency localize and open new band gaps.
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Figure: Isosurface of the DOS of the 1D band formed in the band gap of the Ge(001):H surface when a line of
hydrogen atoms are removed
On-surface chemistry: cyclodehydrogenation of PAH catalyzed
by metal surfaces.
I. Palacio1, A.L. Pinardi1, G. Otero-Irurueta1, J.I. Martinez1, M.F. López1, J. Méndez1,
J.A. Martín-Gago1
Instituto de Ciencia de Materiales de Madrid ((ICMM), Madrid, Spain
One of the main goals in nanotechnology is to assemble low dimensional molecular networks
in order to create new nano-objects. For that purpose, on-surface chemistry is one of the most
powerful and suitable bottom-up approaches that can be employed. Dehydrogenation
reactions of polycyclic aromatic hydrocarbons (PAH) catalyzed by metal surfaces allow a
control at the atomic level of the resultant outcome, with the correct choice of the geometry
of the precursor and on the type of metallic surface1.
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In this work, we show that the strength of the PAH-substrate interaction rules the competitive
reaction pathways (cyclodehydrogenation versus dehydrogenative polymerisation). Starting
from the same molecular precursor (C57H33N3 or C40H24N2 (DiPy[5]DBH) and controlling its
diffusion by the nature of the supporting surface (Au(111) or Pt(111)), temperature-triggered
dehydrogenation takes place to provide molecular or polymeric structures of variable
dimensionality2-3.
Combining advanced in-situ surface techniques as STM and NEXAFS with theoretical ab-initio
calculations we have been able to achieve a complete understanding of the self-assembling of
molecular precursors on surfaces. By merging information from these techniques and different
single-crystal metal substrates, we report on the diffusion control of competitive
intramolecular and intermolecular dehydrogenative processes respectively called
cyclodehydrogenation and dehydrogenative polymerisation, which operate in the on-surface
synthesis of N-doped fullerene, nanographene, polyaromatic network, membrane or
grapheme (Fig. 1). By choosing the appropriate N-heteroaromatic precursors and by
controlling their diffusion, the on-surface (cyclo)dehydrogenation can either lead to
monomolecular triazafullerenes and diazahexabenzocoronenes (N-doped nanographene), or
to N-doped polymeric networks.
Fig. 1: The heteroaromatic precursors 1 and 4 subjected to controlled on-surface dehydrogenation. 1 and 4 may
form respectively (i) N-doped triazafullerene 2 or 2,5-diazahexabenzocoronene 5 (through intramolecular
cyclodehydrogenation) or (ii) branched 2D polyaromatic architectures 3 or 6 (both through intermolecular
dehydrogenative polymerisation and intramolecular cyclodehydrogenation).
Méndez, J.; López, M. F.; Martín-Gago, J. A., Chem. Soc. Rev. 40, 4578 (2011).
A.L. Pinardi, G. Otero-Irurueta, I. Palacio, J.I. Martinez, B. Gomez-Lor, A. Jančařík, I.G. Stará, I. Starý, M.F.
López, J. Méndez, J.A. Martín-Gago. ACS Nano. 7, 3676(2013).
A.L. Pinardi, J.I. Martinez, A. Jančařík, I.G. Stará, I. Starý, M.F. López, J. Méndez, J.A. Martín-Gago. Chem.
Commun., 50, 1555 (2014)
P45
Substrate-Induced Stabilization And Reconstruction Of Zigzag
Edges In Graphene Nanoislands On Ni(111)
1,2
6
3
4
1
1
M. Olle , A. García-Lekue , D. Sánchez-Portal , J.J. Palacios , A. Mugarza , G. Ceballos ,
P. Gambardella
1
1,2,5
Catalan Institute of Nanoscience and Nanotechnology (ICN2), UAB Campus, E-08193 Bellaterra
2
(Barcelona), Spain; Department of Materials, Eidgenössische Technische Hochschule (ETH) Zurich,
3
Schafmattstrasse 30, CH-8093 Zurich, Switzerland; Donostia International Physics Center (DIPC), Paseo
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Manuel de Lardizabal 4, E-20018 San Sebastian, Spain, and Centro de Fisica de Materiales CFM-MPC,
4
Centro Mixto CSIC-UPV, Apdo. 1072, San Sebastian, Spain; Departamento de Física de la Materia
5
Condensada, Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain; Instituciò Catalana
6
de Recerca i Estudis Avancats (ICREA), E-08193 Barcelona, Spain; Donostia International Physics Center
(DIPC), Paseo Manuel de Lardizabal 4, E-20018 San Sebastian, Spain, and IKERBASQUE, Basque
Foundation for Science, E-48011, Bilbao, Spain
A combination of high resolution scanning tunnel microscopy and density functional theory
(DFT) has been used to investigate the atomic structure of triangular and hexagonal graphene
nanoislands on Ni(111). Due to the 1x1 stacking of graphene on Ni(111), this system is an ideal
candidate to study the interaction between the metallic substrate and the graphene edges.
Both triangular and hexagonal graphene islands are found to possess a top-fcc stacking with
zigzag edges. Moreover, we show that the substrate has a determinant effect on the
stabilization and reconstruction of zigzag edges, and can selectively influence the edge
structure. Interestingly, we reveal that the reconstruction of the edge is determined by the
registry of the edge carbon atoms with the substrate. This is clearly seen for the hexagonal
islands, where half of the edges present a zigzag structure, while the other half show a
pentagon-heptagon reconstruction. Based on our DFT calculations and predictions of the
islands shape, we speculate that the energy barriers associated with the edge reconstruction
could control the formation of either triangular or hexagonal islands depending on the exact
growth conditions.
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Adsorption site dependence of vibrational excitations of
molecular hydrogen
E.Carbonell1, M. Corso1,2, J. Li1, M. Borinaga1, J.I. Pascual1,2
1
2
CIC nanoGUNE, 20018 Donostia-San Sebastián, Basque Country, Spain IKERBASQUE, Basque
Foundation for Science, 48011 Bilbao, BasqueCountry, Spain
97
Transition-metal phtalocyanines are a well-known class of molecules used as model to study
the interaction between metal surfaces and metal-organic compounds [1][2]. These kind of
metal-organic complexes present a wide range of properties and functionalities which depend
on the coordination of their central metal ion, such as magnetism or the adsorption of small
gas molecules [3]. In this work we study Chlorinated Manganese Phtalocyanine (Cl-MnPc)
molecules deposited on a Ag (111) substrate. We explore the adsorption characteristics of this
system by means of a combined Low Temperature Scanning Tunneling and Atomic Force
Microscope. After deposition on a room temperature substrate, a fraction of (dechlorinated)
MnPc molecules coexist with Cl-MnPc on the surface. Moreover, Cl-MnPc can be controllably
dechlorinated after the evaporation process. We find that both molecules are a preferential
site of adsorption for molecular Hydrogen, which is known to present a bistable vibrationally
mediated behavior depending on its different adsorption configurations [4]. Inelastic tunneling
of electrons from a STM can excite such bistability which induces a fingerprint close to zerobias on differential conductance measurements. Additionally, force spectra reveal differences
on the electrostatic forces exerted between the tip and the molecule when the tunneling
electrons trigger such hydrogen fluctuations. We find that these fingerprints are strongly
modified by the presence or absence of Chlorine atoms in the phtalocyanine molecules.
Figure 1: STM image of a self assembled island of Cl-MnPc. MnPcs coexist both in the island and in the Ag (111)
surface
A. Mugarza, R.Robles, C.Krull, R. Korytár, N. Lorente, and P. Gambardella, Phys. Rev B 85, 155437 (2012)
Ying-Shuang Fu, Shuai-Hua Ji, Xi Chen, Xu-Cun Ma, Rui Wu, Chen-Chen Wang, Wen-Hui Duan, Xiao-Hui Qiu, Bo
Sun, Ping Zhang, Jin-Feng Jia, and Qi-Kun Xue, Phys. Rev. Lett. 99, 256601 (2007)
K. Seufert, W. Auwärter and J.V. Barth, J. Am. Chem. Soc. 132, 18141-18146 (2010)
C. Lotze, M. Corso, K.J. Franke, F. von Oppen and J.I. Pascual, Science 338, 779 (2012)
P47
2D To 1D Transition Of Surface States Investigated On
Bismuth Curved Crystals
Jorge Lobo-Checa1, Federico Mazzola2, Luca Barreto3, Frederik M. Schiller1, Justin W.
Wells2, Nicholas C. Plumb4, Johan Adell5, Philip Hofmann3, J. Enrique Ortega1,6
1
Centro de Física de Materiales (CSIC/UPV-EHU), Manuel Lardizábal 5, E-20018 San Sebastián, Spain;
2
Department of Physics, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim,
3
Norway; Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus
98
4
University, 8000 Aarhus C, Denmark; Swiss Light Source, Paul-Scherrer-Institut, 5232 Villigen,
5
6
Switzerland; MAX IV Laboratory, Lund University, P.O. Box 118, 221 00 Lund, Sweden; Departamento
Física Aplicada I, Universidad del País Vasco, E-20018 Donostia-San Sebastián, Spain
Bismuth is a semimetal whose surface shows better metal behaviour than its bulk counterpart
due to the presence of metallic-like surface states. These are spin-split given its large atomic
weight and spin orbit interaction [1]. Depending on the crystal termination these states
behave as two dimensional (2D), delocalized states, or one dimensional (1D), localized states
[2]. Such modification of the electron wavefunction is induced by the presence of step arrays,
by repulsive scattering at steps and confinement within terraces [3] and has been widely
explored for Shockley states in noble metals [3-8]. Semimetals have not received such a
widespread attention but the investigating of this 2D to 1D transition is particularly interesting
since Bi is very close to being a topological insulator and great interest has emerged in
topologically guaranteed 1D surface states.
We present a study that finely explores the 1D - 2D transition in Bismuth surface states using a
curved crystal (see Fig. 1). Such special samples allows for a smooth variation of the surface
orientation, which translates into a smooth variation of the step separation, i.e. the step
potential barriers. The evolution of the electronic structure is investigated by state-of-the-art
ARPES and correlated to the local structure obtained from STM and LEED. We find that this
transition is very different from the noble metal curved surfaces because we do not observe
umklapps and also the surface states are referred to the rhombic (111) direction of the crystal
instead of the projection of the L point on the surface. Such results, to our knowledge, have
never been reported.
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Ph. Hofmann, Prog. In Surf. Sci. 81,191 (2006).
J. W. Wells et al., Phys. Rev. Lett., 102, 096802 (2009).
L. Bürgi et al., Phys. Rev. Lett. 81, 5370 (1998).
A. Mugarza et al., J. Phys. Cond. Matt. 15, S3281 (2003).
M. Corso et al., J. Phys. Cond. Matt. 21, 353001 (2009).
J. E. Ortega et al., Phys. Rev. B 83, 085411 (2011).
J. E. Ortega et al., Phys. Rev. B. 87, 115425 (2013).
J. Lobo-Checa et al., Phys. Rev. B, 84, 245419 (2011).
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P48
A Toolbox For Controlling Quantum States In Organic
Monolayers
Bernhard Kretz1, David A. Egger1, Egbert Zojer1
1 Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
The possibility of controlling interface properties “at will” holds a high promise for hybrid
electronics and spintronics applications. Covalently-bonded selfassembled monolayers (SAMs)
are very well suited for such interface modifications, as they offer a high flexibility regarding
the design of their electronic properties. For example, the distribution of dipolar groups along
the backbones of thiolate-bonded self-assembled monolayers has been shown to cause a
modification of the electron wave-function and the vacuum level1. In particular, molecular
orbitals like the highest occupied molecular orbital (HOMO) and the lowest unoccupied orbital
(LUMO) get shifted in energy and localized on opposite ends of the molecular layer2. The latter
can, for example, be interesting for separating electrons and holes in a device. Embedding
radical groups in SAMs3,4 could be of interest for spintronics devices by enabling spin
polarized transport5. Building on these results, in this work we perform band structure
calculations using density functional theory on tolanthiolate-based SAMs where dipolar and
radical groups are distributed along the SAMs. The aim of distributing different functional units
along the backbones of SAMs is the development of a toolbox for controlling interface
properties. Our results show that collective electrostatic effects induced by dipolar elements
can help achieving localization of orbitals in a specific manner and, moreover, can be used to
build quantum-cascade and quantum-well like structures. Furthermore, we suggest that
embedding radical groups enables spin sensitivity in specific regions of an organic monolayer.
[1].
D. A. Egger, F. Rissner, G. M. Rangger, O. T. Hofmann, L. Wittwer, G. Heimel, and E. Zojer, Phys.
Chem. Chem. Phys., 2010, 12, 4291–4294
[2].
F. Rissner, D. A. Egger, A. Natan, T. Körzdörfer, S. Kümmel, L. Kronik, and Egbert Zojer, J. Am.
Chem. Soc. 2011, 133, 18634
[3].
G. Heimel, E. Zojer, L. Romaner , J.-L. Brédas and F. Stellacci, Nano Lett., 2009, 9 (7), pp 2559–
2564
[4].
N. Crivillers, C. Munuera, M. Mas-Torrent, C. Simão, S. T. Bromley, C. Ocal, C. Rovira, and J.
Veciana, Adv. Mater. 2009, 21, 1177–1181
[5].
S. Chakrabarti and A. J. Pal, Appl. Phys. Lett. 104, 013305 (2014)
P49
Cementing Proteins Provide Extra Mechanical Stabilization To
Viral Cages
M. Hernando-Pérez1, S. Kruse2, E. Nakatani2, C. E. Catalano2, P.J. de Pablo1
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1 Departamento de Física de la Materia Condensada and Condensed Matter Physics Center (IFIMAC),
Universidad Autónoma de Madrid 28049 Madrid, Spain; 2 Department of Medicinal Chemistry, School of
Pharmacy, University of Washington, H-172 Health Sciences Building, Box 357610, Seattle, WA 98195
The study of virus shell stability is key not only for gaining insights into their biological cycle,
but also for using viral capsids in materials science. The strength of viral particles depends
profoundly on their structural changes occurring during maturation, whose final step in many
capsids requires the specific binding of decoration proteins to the viral shell. Therefore, we
have characterized the mechanical stability of gpD-free and gpD-decorated bacteriophage
lambda capsids. Our data demonstrate that the incorporation of gpD protein into the lambda
shell imparts a major mechanical reinforcement that resists punctual deformations. We further
interrogated lambda particles stability with molecular fatigue experiments, which resemble
the sub-lethal Brownian collisions of virus shells with macromolecules in crowded
environments. These novel results show that decorated particles are especially robust against
collisions of a few kBT, which approximate those anticipated from molecular insults in the
environment.
P50
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Doping Of The Surface Of A Topological Insulator With Co
Adatoms
O
M. C. Martínez-Velarte1,2, M. Moro-Lagares1,2, Trevor M. Riedemann3, Thomas A.
Lograsso3,4, L. Morellón1,2, M. R. Ibarra1,2, D. Serrate1,2
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1 Instituto de Nanociencia de Aragón (INA) and Laboratory for Advanced Microscopy (LMA), University
of Zaragoza, Spain; 2 Dpto. de Física de la Materia Condensada, Universidad de Zaragoza, Spain; 3 Ames
Laboratory, Ames, IA 50011, USA; 4 Department of Materials Sciences and Engineering, Iowa State
University, Ames, IA 50011 USA
Topological Insulators (TIs) are a new electronic state of matter which has been amply
investigated during the last years due to its unique properties which have great potential for
spintronic applications. TIs are materials with a bulk energy gap and metallic surface states [1].
Due to time-reversal symmetry and spinorbit coupling, these surface states behave as Dirac
Fermions and exhibit a peculiar k-dependent spin-texture. As a result, electron backscattering
becomes quantum-mechanically prohibited, and surface states are expected to be robust
against non-magnetic impurities or defects.
A large number of Bi-based ternary compounds have been theoretically predicted and
experimentally proved to be topological insulators. Band structure calculations of Bi2Se2Te
have predicted a TI state, with an isolated Dirac Point [2]. ARPES measurements of the
occupied density of states (DOS) near the Fermi level support this calculations [3]. Here we
show low temperature (4.7 K) Scanning Tunnelling Microscopy (STM) and Spectroscopy (STS)
measurements on a Bi2Se2Te crystal, gaining large spatial resolution of both the occupied and
unoccupied local DOS. The crystals were grown by the Bridgman technique. Atomically
resolved STM images of the crystal surface shows a binary chemical contrast which is likely due
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to Te and Se segregation in regions of a few nm in size. Our STS data is fairly dependent on
positioning the tip over Te or Se regions.
Moreover, individual Co atoms were deposited on the crystal surface held at T<6K to prevent
atom diffusion. Despite of the low crystal temperature during evaporation, adatoms and
subsurface substitutional defects were found. The former shows an atomic resonance peak on
the STS spectra at around -650 mV. Importantly, valence and conduction bulk bands undergo a
shift towards lower energies upon Co doping.
In conclusion, we have succeeded in doping the 2-D topological surface states of Bi2Se2Te in
the range of dispersed magnetic atoms. Our energy resolved STS measurements unveil its
impact on the bulk electronic bands and the dispersion relation of the surface Dirac-fermions.
[1]. M. Z. Hasan et al., Rev. Mod. Phys., vol. 82, no. 4, pp. 3045–3067, Nov. 2010.
[2]. M. Z. Hasan et al., Phys. Rev. B, vol. 85, no. 23, p. 235406, Jun. 2012.
[3]. L. Bao et al., Sci. Rep., vol. 2, p. 726, Jan. 2012.
P51
Probing the magnetic interaction between single Cr atoms
Zsolt Majzik1, José Ignacio Pascual1,2
1
CIC nanoGUNE, Donostia-San Sebastián, Spain
2
Ikerbasque, Basque Foundation for Science, Bilbao, Spain
E-mail: [email protected]
In the last decade it has been shown that magnetic properties of a single atom can be probed
by inelastic electron tunneling spectroscopy [1]. In addition, magnetic nanostructures have
been routinely assembled via atomic manipulation [2]. In the tunneling junction, spin
excitation is induced if the bias voltage exceeds the threshold energy for excitation. The spin
excitation process allows the electrons to tunnel inelastically leading to a stepwise increase in
the conductance over the threshold bias [1,2].
Here we aimed to study the magnetic characteristics of isolated Cr atoms adsorbed on
Cu2N/Cu(100) surface. Cr atoms were deposited and their properties were investigated at 1.1 K
in a SPECS JT STM that has a magnetic field up to 3 T perpendicular to the sample.
Different inelastic tunneling spectra were observed over Cr atoms adsorbed on N sites than on
Cu sites. In the first case we interpret our spectra as interplay between spin excitation and
Kondo screening effect, which appears here at larger biases. However, if the Cr atom adsorbed
on the Cu site, the Kondo effect does not appear in the spectra, only a spin excitation has a
contribution near the Fermi level. Our results suggest that the spin configuration of the Cr
atom varies among different adsorption positions.
By atomic manipulation we have constructed Cr dimers with different interatomic spacing (see
Fig). Among the investigated pairs, the strength of the coupling, J, was the strongest when the
Cr atoms were occupying the nearest Cu sites separated by a single N atom (JA). The coupling
becomes significantly weaker if the Cr atoms are placed diagonally (JB). Interestingly, increasing
further the interatomic separation induces less significant quench in the coupling energy (JC).
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In a dimer, the close proximity of the Cr adatoms induces a local crystal strain. Beside the
variation in the strength of the magnetic exchange interaction, the strain-enhanced anisotropy
has a strong impact on the stability of the antiferromagnetic coupling [3]. The combination of
both effects explains well our large variation of J.
[1]. A. J. Heinrich, J. A. Gupta, C. P. Lutz, D. M. Eigler, Science 306, 466 (2004)
[2]. C. F. Hirjibehedin, C. P. Lutz, A. J. Heinrich, Science 312, 1021 (2006)
[3]. B. Bryant, A. Spinelli, J.J. T. Wagenaar, M. Gerrits and A. F. Otte, Phys. Rev. Lett 111, 127203 (2013)
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Are Textbooks Always Right? An AFM Search For Protein
Packing Defects In Viruses
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Aitziber Eleta-Lopez1, Alba Centeno2, Amaia Pesquera2, Amaia Zurutuza2, Christina
Wege3, Alexander M. Bittner1,4
1 CIC nanoGUNE, Donostia-San Sebastián, Spain
2 Graphenea, Donostia-San Sebastián, Spain
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3 Universität Stuttgart, Germany
4 Ikerbasque, Bilbo, Spain
Tobacco mosaic virus (TMV) is the first isolated and characterized virus [1, 2]. It is also one of
the simplest viruses, composed of a single strand of helical RNA, embedded in a helix of 2130
identical coat proteins. In comparison with most other viruses, its biology, chemistry, and
structure are known to exceptional details. This has made TMV a textbook example for viruses,
protein complexes, and nanotubes. TMV measures 300 nm in length and 18 nm in diameter
[3]. The helix pitch (protein-protein distance) is 2.29 nm, determined by X-ray fiber diffraction
and cryo-EM of pure TMV, and by TEM of stained TMV (modified by heavy metal ions), but not
yet by imaging techniques, such as scanning probe [4-7]. Thus, some questions arise: Is this a
technical problem? Do the diffraction and averaging techniques overlook local defects? In this
work, TMV has been imaged by AFM on different flat substrates such as mica, graphite,
graphene and gold. In all the cases the virus length is about 300 nm, but the height varies
depending on the surface. Less than 15 nm is obtained for hydrophilic mica and gold, but
about 17 nm for graphite and graphene. High-resolution topography and phase images show a
stripe-like irregular structure with a pitch of 7-12 nm (figure 1), which is incompatible with the
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textbook data. The study is complemented by imaging the virus with ultra-sharp tips, and by
experiments carried out at various humidity levels.
Figure 1. Phase image of TMV on mica at low humidity environment
[1].
[2].
[3].
[4].
[5].
[6].
[7].
D. Ivanowski, St Petersb. Acad. Imp. Sci. Bull. 35(1892) 65- 70.
M. W. Beijerinck, Verh. Kon. Akad.Wetensch. 5 (1898) 3-21.
J.M. Alonso, M.Ł. Górzny , A.M. Bittner, Trends Biotech. 31(2013) 530-538
A. Kendall, M. McDonald, G. Stubbs, Virology, 369(2007) 226–227
Daniel K. Clare, Elena V. Orlova, J. Strut. Biol. 171 (2010) 303–308
Roy Markham, J. H. Hitchborn, G. J. Hills, Simon Frey, Virology, 22(1964) 342- 359
Shu-wen W. Chen, Michael Odorico, Matthieu Meillan, Luc Vellutini, Jean-Marie Teulon, Pierre Parot,
Bernard Bennetau, Jean-Luc Pellequer, Nanoscale, 5(2013) 10877–10886
P53
A Theoretical DFT Study Of Unusual Moiré Patterns In The
Graphene/Rh(111) System
Ana Martín-Recio1, Antonio J. Martínez-Galera2, José María Gómez-Rodríguez1, Carlos
Romero-Muñiz3, Pablo Pou3, Rubén Pérez3
1 Dpto. Física de la Materia Condensada, U. Autónoma de Madrid, Madrid, Spain
2 Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, Köln, Germany
3 Dpto. Física Teórica de la Materia Condensada, U. Autónoma de Madrid, Madrid, Spain
The growth of graphene on transition metals by means of different techniques has been
intensively studied in recent years [1]. The interaction with the metal not only changes the
electronic properties of graphene, but also influences its geometrical structure, leading in
many cases to periodic Moiré patterns. When the graphene-metal interaction is weak, several
Moiré structures with quite different unit cell sizes are present [2]. On the contrary, in cases
where the interaction is stronger, a single Moire structure tends to dominate. Graphene on
Rh(111), with a 12x12 Moiré structure (11x11 for the Rh(111) substrate) well characterized by
experimental techniques (LEED and UHV-STM) [3] and ab initio DFT calculations [4] was
considered so far to be one of these latter cases [1]. In this work, we report the existence of
new smaller Moiré patterns in the graphene/Rh(111) system identified by VT-STM. These
structures, with very different periodicities, are stable and coexist with the 12x12 Moiré
reported so far. The apparent corrugation of graphene in these structures seems to increase
with the unit cell size of the Moiré pattern. In order to characterize the graphene-Rh
interaction and understand the origin of this trend, we have carried out a systematic DFT study
104
of these new structures (fig.1). Theoretical STM images have been calculated using both a
simple Tersoff-Hamann approximation and a more sophisticated Green-Keldysh transport
formalism. Only a proper calculation of the tunneling current, including explicitly the tip
structure and electronic properties, provides theoretical corrugations in good agreement with
the experiment.
Figure 1: Heights maps (in Å) of two Moiré patterns of different sizes.
[1].
M. Batzill. Surface Science Reports 67, 83 (2012)
[2]. A. J. Martínez-Galera, I. Brihuega, J. M. Gómez-Rodríguez. Nano Letters 11, 3576 (2011)
[3]. E. N. Voloshina, et. al. Applied Physics Letters 100, 241606 (2012) 4. M. Iannuzzi, J. Hutter. Surface Science
605, 1360 (2011)
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S
DFT study of AFM metal oxide imaging modes: Towards
atomic species identification
T
E
R
Diego R. Hermoso1, Milica Todorović1, Harry Mönig2 and Rubén Pérez1,3
1
Depto. Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid (UAM), 28049,
Madrid, Spain
2
Physikalisches Institut, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
3
Condensed Matter Physics Center (IFIMAC), UAM, 28049, Madrid, Spain
Metal oxides have many diverse technological applications in fields ranging from catalysis to
electronics. Scanning probe microscopies have proven their extraordinary capacity in
characterizing the surface properties that govern the chemical and electrical response of metal
oxides at the atomic scale. Here we present a combined experimental and theoretical study on
the Cu(110)-(2x1)O surface [1,2], where the oxide features added rows of alternate copper and
oxygen atoms atop the metal surface (Fig. 1A). Atomic force microscopy (AFM) images of the
metal oxide showed stripes with bright and dark spots (Fig. 1B) but it was not possible to
distinguish between species in the added row. Following our previous study for the Cu(100)(2x1)O system [3], we have used Density functional theory (DFT) calculations for the tip-sample
interaction in order to understand the observed contrast and identify the main image features.
These calculations have been performed with two metal Cu tips with different apex
terminations: a Cu or an O atom. While the tip reactivity and the corresponding forces are
105
S
quite different for each tip termination, (Fig. 1C), we can conclude that maxima in the AFM
images correspond to copper atoms in the added row.
Fig. 1. (A) Side an top view of metal-only (left) and metal oxide (right) of Cu(110)-(2x1)O surface [2]. (B) AFM image
showing metal oxide domain (left) and metal-only domain (right). (C) Theoretical force vs distance spectroscopy
curves obtained from the DFT simulations.
[1]. G. Prévot et al., Surf. Sci. 549 52-66 (2004).
[2]. J. Bamidele et al,. Phys. Rev. B 86, 155422 (2012).
[3]. M. Z. Baykara, et al., Phys. Rev. B 87, 155414 (2013).
P55
Curved Crystals: A different approach to Surface Science
J. E. Ortega1,2,3,4, R. González-Moreno1, F. López-Geijo1, Z. M. Abd-el-Fattah2, J. LoboCheca3, M. Corso2, U. Aseguinolaza2, A. Mugarza5, A. L. Walter4, A. Magaña2, M. Ilyin3,
L.A. Miccio4, M. Abadía2, and F. Schiller1,3
1
BIHURCRYSTAL S.L., San Sebastian
2
Departamento de Física Aplicada I, Universidad del País Vasco UPV/EHU, San Sebastian
3
Centro de Física de Materiales, Centro Mixto CSIC-UPV/EHU, San Sebastian
4
Donostia International Physics Center DIPC, San Sebastian
5
Catalan Institute of Nanotechnology (ICN) Barcelona, Spain
Atomic steps strongly influence many physical-chemical phenomena that occur at surfaces,
such as growth, chemical reactions, and electron scattering. It is therefore desirable to
investigate the role of steps through the accurate control of the step density that can be
achieved with a curved surface. We are capable of fabricating curved surfaces of different
materials with a smooth variation of the crystal orientation (miscut angle) with respect to a
high symmetry plane. Sample shapes and dimensions allow easy processing in vacuum, and are
ideal for the exploration of step-dependent properties through scanning probe techniques,
including 100-micron-size light beams.
It will be shown the powerful analytical capabilities of the curved surface approach, their
advantages with respect to flat surfaces, as well as the new physics that arises by studying
curved crystals: the complexity of the surface state scattering at step arrays of noble metals
106
[1], the interplay of steps and dislocation networks to define exotic 2D lattices and band
structures, the periodic texturing of quantum well states in ultrathin stepped metallic films [2],
the smooth variation of surface core-level shifts in transition metals and overlayers, and the
templated growth of nanostructures, e.g., metallic nanodots on curved oxide surfaces and lowdimensional ferromagnets with exotic magnetic anisotropy tuned on curved W and Pd.
[1].
M. Corso, F. Schiller, L. Fernández, J. Cordón, and J. E. Ortega, J. Phys.: Cond. Matter 21, 353001
(2009); J. E. Ortega, M. Corso, Z. M. Abd-el-Fattah, E. A. Goiri, and F. Schiller Phys. Rev. B 83, 085411
(2011); J. E. Ortega, J. Lobo-Checa, G. Peschel, S. Schirone, Z. M. Abd-el-Fattah, M. Matena, F. Schiller, P.
Borghetti, P. Gambardella, and A. Mugarza, Phys. Rev. B 87, 115425 (2013).
[2]. F. Schiller at al. (submitted to N. J. of Physics).
P56
Characterization Of Mn0.006NbSe2 From Bulk To Few Layers
Alexandre Correa orellana1, Carmen Munuera1, Roberto Fabián Luccas1, Mar García
Hernández1, Hermann Suderow2, Federico Mompean1
P
1 Instituto de Ciencia de Materiales de Madrid
2 Universidad Autónoma de Madrid
Transition metal dichalcogenides (TMDs) have already shown significant applications in various
fields of optics, electrochemistry, electronics and sensors. In recent years, after the discovery
of graphene, they have regained research interest due to their layered form that allows their
exfoliation into small thicknesses containing mono- or multiple layers. Interesting thicknessdependent properties in these systems have been theoretically predicted, such as the
realization of anomalous superconducting states when reaching the single layer. In addition,
the intercalation of metals atoms between the van der Wals planes in TMDs is a particularly
appealing approach to modify their physical properties, such as the charge density waves
(CDW) and superconducting states [1,2,3]
In this work we have focused on the characterization of intercalated NbSe2 (Mn0.006NbSe2) in
bulk and on its exfoliation down to few layers. 2H-NbSe2 present a charge density wave
(TCDW=35K) and superconducting (TC=7.2K) states that are modified upon exfoliation [4]. Bulk
Mn0.006NbSe2 shows structural differences when compared to the pure system as confirmed
by X-ray diffraction data. In addition, we obtain a superconducting critical temperature of 6K
(1.2K lower than in the NbSe2 pure material). Recently we have succeeded in the exfoliation of
this material down to few layers flakes with the scotch tape method. Atomic Force Microscopy
(AFM) and Raman spectroscopy have been used for the characterization of these flakes.
[1].
[2].
[3].
[4].
I. Naik, AIP Conf. Proc. 1349 (2011) 883
L.J. Li et al., J. Magn. Magn. Mater. 323 (2011) 2536
V.I. Maksimov et al., J. Alloy Comp. 384(2004) 33
N. E. Staley et al., Phys. Rev. B 80 (2009) 184505
107
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P57
A digital electronics for fast SPM
Ignacio Horcas1,2, A. Gimeno1, P. Ares1,2, J. Gómez-Herrero2
1 Nanotec Electronica
2 Universidad Autónoma de Madrid
In this work, we present a new electronics for fast SPM control. The design is based on the
combination of a state of the art Digital Signal Processor (DSP) board (TMDSEVM6678) and a
Field Programmable Gate Array (FPGA) board that controls 16x16 bits resolution DACs plus
16x16 bit resolution ADCs. Using this new set up we are able to obtain acquisition rates as high
as 1 frame/s (128x128 points) in standard calibration grids.
108
List of Participants
Last Name and Family Name
Email Address
1
ABAD LOPEZ JOSE
[email protected]
2
ABADIA MIKEL
[email protected]
3
ABALLE LUCIA
[email protected]
4
AGUSTINA ASENJO
[email protected]
5
ALMONTE GARCIA LISA
[email protected]
6
AMENABAR ALTUNA IBAN
[email protected]
7
ANADON ALBERTO
8
ARES PABLO
[email protected]
9
ARNAU ANDRES
[email protected]
10
ARNAUDAS JOSE IGNANCIO
[email protected]
11
AZPEITIA JON
[email protected]
12
BARJA MARTINEZ SARA
[email protected]
13
BARO VIDAL ARTURO
[email protected]
14
BERGANZA EGUIARTE EIDER
[email protected]
15
BERGER JAN
[email protected]
16
BRIHUEGA IVAN
[email protected]
17
CARBONELL SANROMA EDUARD
[email protected]
18
CARRASCO PULIDO CAROLINA
[email protected]
19
CIRIA MIGUEL
[email protected]
20
COFFEY BLANCO DAVID
[email protected]
21
COLCHERO PAETZ JAIME
[email protected]
22
CORREA ARISTIZABAL ALEXANDER
[email protected]
23
CORREA ORELLANA ALEXANDRE
[email protected]
24
CORSO MARTINA
[email protected]
25
DAZA RAFAEL
[email protected]
109
26
DE LA TORRE CERDEÑO BRUNO
[email protected]
27
DE OTEYZA DIMAS
[email protected]
28
DE PABLO PEDRO
[email protected]
29
DELGADO FERNANDO
[email protected]
30
DIEZ FERRER JOSE LUIS
[email protected]
31
DOMINGO MARIMON NEUS
[email protected]
32
ELETA LOPEZ AITZIBER
[email protected]
33
ELLNER MICHAEL
[email protected]
34
ENGELUND MADS
[email protected]
35
FAROKH PAYAM AMIR
[email protected]
36
FERNANDEZ GOMEZ-RECUERO LAURA
[email protected]
37
FERNANDEZ TORRENTE ISABEL
[email protected]
38
FRANKE KATHARINA
[email protected]
39
FUENTES PEREZ MARIA EUGENIA
[email protected]
40
GARCIA ARRIBAS ARITZ
[email protected]
41
GARCIA MARTIN JOSE MIGUEL
[email protected]
42
GARCIA-LEKUE ARAN
[email protected]
43
GASTALDO MICHELE
[email protected]
44
GERBER CHRISTOPH
[email protected]
45
GOMEZ MOÑIVAS SACHA
[email protected]
46
GOMEZ RODRIGUEZ JOSE MARIA
[email protected]
47
GOMEZ-HERRERO JULIO
[email protected]
48
GONZALEZ HERRERO HECTOR
[email protected]
49
GONZALEZ MARTINEZ JUAN FRANCISCO
[email protected]
50
GONZALEZ MORENO RUBEN
[email protected]
51
GOVYADINOV ALEXANDER
[email protected]
52
HEINRICH BENJAMIN
[email protected]
110
53
HERNANDEZ-RODRIGUEZ IRENE
[email protected]
54
HERNANDO MERCEDES
[email protected]
55
HORCAS IGNACIO
[email protected]
56
JAAFAR RUIZ-CASTELLANOS MIRIAM
[email protected]
57
JELINEK PAVEL
[email protected]
58
JÖRG SCHÖNFELDER
[email protected]
59
KAIDATZIS ANDREAS
[email protected]
60
KRETZ BERNHARD
[email protected]
61
LLAURO PORTELL AIDA
[email protected]
62
LOBO-CHECA JORGE
[email protected]
63
LOPEZ FAGUNDEZ MARIA FRANCISCA
[email protected]
64
LOPEZ FRANCISCO
[email protected]
65
LOPEZ MIR LAURA
[email protected]
66
LOPEZ-POLIN GUILLERMO
[email protected]
67
MAGALI PHANER GOUTORBE
[email protected]
68
MAGAÑA VICANDI ANA
[email protected]
69
MAJZIK ZSOLT
[email protected]
70
MARCO ALEX
[email protected]
71
MARTIN GAGO JOSE ANGEL
[email protected]
72
MARTINEZ JIMENEZ DANIEL
[email protected]
73
MARTIN RECIO ANA
[email protected]
74
MARTINEZ BLANCO JESUS
[email protected]
75
MARTINEZ CASTRO JOSE
[email protected]
76
MARTINEZ RUIZ JOSE IGNACIO
[email protected]
77
MARTINEZ VELARTE MARI CARMEN
[email protected]
78
MENDEZ PEREZ CAMARERO JAVIER
[email protected]
79
MERINO PABLO
[email protected]
111
80
MICCIO LUIS ALEJANDRO
[email protected]
81
MORENO HERRERO FERNANDO
[email protected]
82
MORENO SIERRA CESAR
[email protected]
83
MORENO UGEDA MIGUEL
[email protected]
84
MORO LAGARES MARIA
[email protected]
85
MORQUILLAS AZPIAZU NIEVES
[email protected]
86
MUGARZA AITOR
[email protected]
87
MUNUERA LOPEZ CARMEN
[email protected]
88
NAVARRO PAREDES VIOLETA
[email protected]
89
ORMAZA-SAEZMIERA MAIDER
[email protected]
90
ORTEGA ENRIQUE
[email protected]
91
ORTEGA ESTEBAN ALVARO
[email protected]
92
OTERO MARTIN ROBERTO
[email protected]
93
PALACIO RODRIGUEZ IRENE
[email protected]
94
PALACIOS LIDON ELISA
[email protected]
95
PASCUAL IGNACIO
[email protected]
96
PEÑA GIL DIEGO
[email protected]
97
PEREZ PERRINO ALMA EVA
[email protected]
98
PEREZ RODRIGUEZ ANA
[email protected]
99
PEREZ RUBEN
[email protected]
100
PIANTEK MARTEN
[email protected]
101
POU PABLO
[email protected]
102
ARVIND RAMAN
[email protected]
103
REIFENBERGER RONALD
[email protected]
104
RODRIGO INSAUSTI LUCIA
[email protected]
105
RODRIGUEZ HERMOSO DIEGO
[email protected]
106
ROGERO CELIA
[email protected]
112
107
ROMERO MUNIZ CARLOS
[email protected]
108
RUBIO VERDU CARMEN
[email protected]
109
SALGADO GARCES CARLOS EDUARDO
[email protected]
110
SANCHEZ LACASA JESUS
[email protected]
111
SANCHEZ PORTAL DANIEL
[email protected]
112
SANCHEZ SANCHEZ CARLOS
[email protected]
113
SARASOLA IÑIGUEZ ANE
[email protected]
114
SCHIRONE STEFANO
[email protected]
115
SERRATE DONOSO DAVID
[email protected]
116
SIMIC-MILOSEVIC VIOLETA
[email protected]
117
THOMSON NEIL
[email protected]
118
URDAMPILLETA MARTA
[email protected]
119
VERDAGUER ALBERT
[email protected]
120
VILHENA GUILHERME
[email protected]
121
VITALI LUCIA
[email protected]
122
ZOTTI LINDA ANGELA
[email protected]
113
Session 4. AFM applications in biology
9:15
THRUSDAY 28
9:00
Welcome words
Session 1. Magnetism
9:15
Neil H.Thomson
WEDNESDAY 27
Katharina Franke
10:00
Magali Phaner
10:20
Alma Eva
10:40
Alvaro Ortega
11:00
Gilherme Vilhena
11:20
Iban Amenabar
11:40
COFFEE BREAK
Session 5. Graphene and 2D-systems II
12:00
Aran García
12:20
Ana Martín
12:40
Guillermo Lopez
13:00
Neus Domingo
13:20
LUNCH
20:30
17:50
Bus to conference dinner
POSTER SESSION
14:30 Organizing Committee Meeting
Session 6. New developments & related techniques
15:30
Violeta Navarro
15:50
Elisa Palacios
16:10
Alejandro Miccio
16:30
COFFEE BREAK
16:50
Carolina Carrasco
17:10
Lucía Aballe
17:30
Alexander Govyadinov
10:00
David Coffey
10:20
Fernando Delgado
10:40
Pablo Ares
11:00
Jesús Martínez
11:20
María Moro
11:40
COFFEE BREAK
Session 2. Syntesis on Surfaces
12:00
Carlos Sanchez
12:20
Roberto Otero
12:40
José I. Martínez
13:00
Maider Ormaza
13:20
LUNCH
Free time
Session 3. Graphene and 2D-systems I
15:30
Stefano Schirone
15:50
Héctor González
16:10
Pablo Merino
16:30
Miguel Moreno
16:50
Cármen Rubio
17:10
COFFEE BREAK
Session Tribute to Prof. A. Baró
17:30
Welcome words
17:35
Christoph Gerber
18:05
Ron Reifenberger
18:35
Arvind Raman
19:05
Ignacio Pascual
20:00
FRIDAY 29
Session 7. Combined AFM/STM I
10:15
Pavel Jelinek
11:00
Dimas de Oteyza
11:20
Amir Farokh
11:40
COFFEE BREAK
Session 8. Combined AFM/STM II
12:00
Cesar Moreno
12:20
Albert Verdaguer
12:40
Miriam Jaafar
13:00
Poster Prizes
13:20
Final remarks

Book of abstracts - Donostia International Physics Center

Transcription

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