Clemens Barth
Heterogeneous catalysis, oxide surfaces, metal nanoparticles, molecular self-assembly of molecules, noncontact AFM (nc-AFM), Kelvin probe force microscopy (KPFM)
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I am a research director (directeur de recherche) in the French CNRS (Institut de Physique, Section 05, condensed matter) and work in the CINaM institut, which is located on the Campus of Luminy in Marseille, in the south part of France. My work deals with the fundamental research of insulating ionic surfaces (oxide surfaces, bulk ionic crystal surfaces, thin insulating ionic films on metal surfaces) and of supported metal nanoparticles (NPs) and small functionalized molecules, which I characterzie by noncontact atomic force microscopy (nc-AFM) and Kelvin probe force microscopy (KPFM). Some of my results are summarized in a recent review (Advanced Materials 23 (2011) 477). The main keywords are:
Surfaces
- - Atomic surface structure
- - Surface defects
- - Surface reconstruction
- - Dopage, influence of impurities (e.g. surface double layer or Debye-Frenkel layer)
- - Large defect systems, precipitation and new phase creation (e.g. Suzuki phase)
- - Nanostructuration
Metal nanoparticles (NPs)
- - Growth, nucleation, sintering, morphology, structure
- - Work function
- - Charge and polarization related phenomena
- - Adsorption and contamination of species at NPs (carbon)
Molecules
- - Functionalized molecules
- - Thin molecular films
- - Adsorption/desorption, charge matching
- - Supramolecular self-assembly, pi-pi stacking
Heterogeneous model catalysis. A large part of my research is located in heterogeneous model catalysis. In particular, I focus on the morphology, atomic structure, defects and charge state of oxide surfaces (MgO, Al2O3 and since recently also ceria). Furthermore, I characterize supported gold (AuNPs) and palladium nanoparticles (PdNPs), their morphology and structure but also charge related phenomena. Recently, I started to 'visualize' the reactivity of metal NPs by using the Kelvin microscope and monitoring work function changes at NPs. For instance, we could observe strong WF changes upon carbon contamination at PdNPs. Although alkali halides are not relevant in heterogeneous catalysis, they are nevertheless very interesting for me because they are somewhat similar to oxide surfaces. One advantage by using alkali halide surfaces is that they are accessible for high resoultion nc-AFM and KPFM imaging. Furthermore, because the type of surface defects can be narrowed down to only a few the identification of defects is relatively easy to accomplish. For instance, thanks to the Kelvin microscope I could directly evidence the Debye-Frankel layer and with it, I could identify cation vacancies at the steps. A real key advantage of alkal ihalides is that they can be doped with divalent metal impurities (Cd, Mg), which produces new phases in the crystals, like the Suzuki phase. Doping of alkali halides leads to nanostructured insulating surfaces, on which the growth of metal NPs can be confined inside specific surface regions at the nanometer scale. With this, metal NPs with a narrow size distribution are created, with interesting potential applications in heterogeneous model catalysis.
Nanosciences of thin molecular films. The second, smaller part of my research is located in the nanosciences of thin molecular films. On insulating alkali halide surfaces I'm interested in the detailed mechanisms of adsorption and desorption of functionalized molecules. Functionalization of molecules with polar substituents and the charge matching principle, i.e. the electrostatic interaction between polar functional groups of molecules and the ionic sublattices of the surface, are of key interest. Furthermore, phenomena of self-assembly and chirality within molecular films are part of my research. In recent years, I focused on pentahelicene molecules ([5]helicene), functionalized with one or two bromine or cyano substituents (MonoBromo, DiBromo, MonoCyano, DiCyano [5]helicene). The detailed adsorption and self-assembly mechanisms could be described in great detail on the Suzuki NaCl surface.
Atomic force microscopy. The local morphological, structural and electrostatic properties of surfaces are studied at the nanometer and atomic scale with help of local scanning probe techniques in ultra-high vacuum and mostly at room temperature. Because of the insulating character of the materials I use frequency modulated nc-AFM (dynamic SFM), which permits obtaining true atomic resolution imaging. Furthermore, the Kelvin microscope (KPFM) supports the characterization of surfaces and supported nano-objects by detecting the electrostatics of the surface, e.g. the surface work function (WF), and charge and polarization related phenomena. Apart from standard nc-AFM and KPFM, I also have a large interest in the manipulation of metal NPs, including lateral manipulation and charge injection experiments.
nc-AFM: Atomic resolution imaging, constant height mode imaging, force spectroscopy, surface structure determination and identification of atoms, ions and adsorbates, high-resolution imaging of metal NPs, manipulation of metal NPs, molecular resolution
KPFM: Quantitative WF measurements of metal supported thin ionic films, imaging charged defects and charge identification on insulating surfaces, quantitative WF measurements at metal NPs, revealing phenomena like contamination, reactivity related phenomena at metal NPs revealed by WF measurements, charge phenomena at metal NPs, characterization and identification of polar tips, dipole imaging at molecules on insulating surfaces
2023
Characterizing the Water Forming Reaction on Graphite and Ceria Supported Palladium Nanoparticles and Nanoislands by the Work Function
Baptiste Chatelain, Ali El Barraj, Carine Laffon, Philippe Parent, Clemens Barth
Journal of Physical Chemistry C 127:5731-5742 (2023)10.1021/acs.jpcc.2c08447
2021
Collective amplification of nearby nanoparticles in the Coulomb blockade restricted charging of a single nanoparticle
Baptiste Chatelain, Ali El Barraj, Clémence Badie, Lionel Santinacci, Clemens Barth
New Journal of Physics (2021)10.1088/1367-2630/ac38cb
High-temperature oxidation and reduction of the inverse ceria/Cu(111) catalyst characterized by LEED, STM, nc-AFM and KPFM
Ali El Barraj, Baptiste Chatelain, Clemens Barth
Journal of Physics: Condensed Matter (2021)10.1088/1361-648X/ac26f9
2019
Oxygen Adsorption on Graphene-Encapsulated Palladium Nanoparticles Imaged by Kelvin Probe Force Microscopy
Henrik Grönbeck, Clemens Barth
Journal of Physical Chemistry C 123:24615-24625 (2019)10.1021/acs.jpcc.9b07377
Revealing Carbon Phenomena at Palladium Nanoparticles by Analyzing the Work Function
Henrik Grönbeck, Clemens Barth
Journal of Physical Chemistry C 123:4360-4370 (2019)10.1021/acs.jpcc.8b12208
2018
Carbon Precursor Structures and Graphene on Palladium Nanoparticles
Clemens Barth
Journal of Physical Chemistry C 122:522-529 (2018)10.1021/acs.jpcc.7b09885
Stability of Ultrathin Ceria Films on Pt(111) Exposed to Air and Treated in Redox Cycles
Gabriele Gasperi, Paola Luches, Clemens Barth
Journal of Physical Chemistry C 122:25954-25963 (2018)10.1021/acs.jpcc.8b07231
2017
Surface Stabilizes Ceria in Unexpected Stoichiometry
Reinhard Olbrich, Gustavo E Murgida, Valeria Ferrari, Clemens Barth, Ana M Llois, Michael Reichling, M Veronica Ganduglia-Pirovano
Journal of Physical Chemistry C 121:6844-6851 (2017)10.1021/acs.jpcc.7b00956
CO Chemisorption on Ultrathin MgO-Supported Palladium Nanoparticles
Aimeric Ouvrard, Ahmed Ghalgaoui, Carine Michel, Clemens Barth, Jijin Wang, Serge Carrez, Wanquan Zheng, Claude R. Henry, Bernard Bourguignon
Journal of Physical Chemistry C 121:5551-5564 (2017)10.1021/acs.jpcc.6b10595
2016
Advances in the Development of a 10-kA Class REBCO Cable for the EuCARD2 Demonstrator Magnet
A. Badel, A. Ballarino, C. Barth, L. Bottura, M. M. J. Dhalle, J. Fleiter, W. Goldacker, J. Himbele, A. Kario, L. Rossi, A. Rutt, C. Scheuerlein, C. Senatore, P. Tixador, A. Usoskin, Y. Yang
IEEE Transactions on Applied Superconductivity 26:4803908 (2016)10.1109/TASC.2016.2548938
Charging C-60 islands with the AFM tip
Brice Hoff, Claude R. Henry, Clemens Barth
Nanoscale 8:411-419 (2016)10.1039/c5nr04541j
2015
KCl ultra-thin films with polar and non-polar surfaces grown on Si(111)7x7
Igor Beinik, Clemens Barth, Margrit Hanbücken, Laurence Masson
Scientific Reports 5 (2015)10.1038/srep08223
Morphology, Work Function, and Silver Ad-Structures of High-Temperature Grown Ultrathin MgO Films on Ag(001)
F. Mechehoud, C. Barth
2014
Mechanisms of the Adsorption and Self-Assembly of Molecules with Polarized Functional Groups on Insulating Surfaces
B. Hoff, M. Gingras, R. Peresutti, C. R. Henry, A. S. Foster, C. Barth
Kelvin Probe Force Microscopy in Surface Chemistry: Reactivity of Pd Nanoparticles on Highly Oriented Pirolytic Graphite
E. Palacios-Lidon, C. R. Henry, C. Barth
2013
Defect mediated manipulation of nanoclusters on an insulator
T. Hynninen, Gregory Cabailh, A.S. Foster, C. Barth
Scientific Reports 3:1270 (2013)10.1038/srep01270
Atomic Structures of Silicene Layers Grown on Ag(111) : Scanning Tunneling Microscopy and Noncontact Atomic Force Microscopy Observations
Andrea Resta, Thomas Leoni, Clemens Barth, Alain Ranguis, Conrad Becker, Thomas Bruhn, Patrick Vogt, Guy Le Lay
Scientific Reports 3:2399 (2013)10.1038/srep02399
Atomic Structures of Silicene Layers Grown on Ag(111): Scanning Tunneling Microscopy and Noncontact Atomic Force Microscopy Observations
Andrea Resta, Thomas Leoni, Clemens Barth, Alain Ranguis, Conrad Becker, Thomas Bruhn, Patrick Vogt, Guy Le Lay
2012
Two-Dimensional Nanostructured Growth of Nanoclusters and Molecules on Insulating Surfaces
C. Barth, M. Gingras, A.S. Foster, A. Gulans, G. Félix, T. Hynninen, R. Peresutti, C.R. Henry
Thin NaCl films on silver (001): island growth and work function
Gregory Cabailh, Claude R Henry, Clemens Barth
New Journal of Physics 14:103037 (2012)10.1088/1367-2630/14/10/103037
Characterization of atomic step structures on CaF2(111) by their electric potential
H.H. Pieper, C. Barth, M. Reichling
2011
Recent Trends in Surface Characterization and Chemistry with High-Resolution Scanning Force Methods
C. Barth, A.S. Foster, C.R. Henry, A.L. Shluger
Polarized Tips or Surfaces: Consequences in Kelvin Probe Force Microscopy
T. Hynninen, A.S. Foster, C. Barth
e-Journal of Surface Science and Nanotechnology 9:6-14 (2011)
Small Molecule-Mediated Activation of the Integrin CD11b/CD18 Reduces Inflammatory Disease
D. Maiguel, M. Faridi, C. Wei, Y. Kuwano, K. Balla, D. Hernandez, C. Barth, G. Lugo, M. Donnelly, A. Nayer, L. Moita, S. Schurer, D. Traver, P. Ruiz, R. Vazquez-Padron, K. Ley, J. Reiser, V. Gupta
Science Signaling 4:ra57-ra57 (2011)10.1126/scisignal.2001811
Characterization of Thin MgO Films on Ag(001) by Low-Energy Electron Diffraction and Scanning Tunneling Microscopy
A. Ouvrard, J. Niebauer, A. Ghalgaoui, C. Barth, C.R. Henry, B. Bourguignon
2010
AFM tip characterization by Kelvin probe force microscopy
C. Barth, T. Hymninen, M. Bieletzki, C.R. Henry, A.S. Foster, F. Esch, U. Heiz
New Journal of Physics 12:093024 (2010)10.1088/1367-2630/12/9/093024
Topography and work function measurements of thin MgO(001) films on Ag(001) by nc-AFM and KPFM
M. Bielezki, T. Soini, M. Pivetta, C.R. Henry, A.S. Foster, F. Esch, C. Barth, U. Heiz
TEM-assisted dynamic scanning force microscope imaging of (001) antigorite: Surfaces and steps on a modulated silicate
E. Palacios-Lidon, O. Grauby, C. Henry, J.-P. Astier, C. Barth, Alain Baronnet
Ultrathin magnesia films as support for molecules and metal clusters: Tuning reactivity by thickness and composition
M.E. Vaida, T.M. Bernhardt, C. Barth, F. Esch, U. Heiz, U. Landman
2009
Kelvin probe force microscopy on MgO(001) surfaces and supported Pd nanoclusters
C. Barth, C.R. Henry