Dr Christophe Humbert, Université Paris-Sud, France.
Nonlinear Vibrational and Electronic Spectroscopy at Interfaces: A Probe Travelling from the Atom to Complex Systems
Surfaces and interfaces play a vital role in Chemistry and Physics because they are the place where fundamental reactions occur between molecules when two materials differing by their nature and/or their physical phase are in interaction. Vibrational spectroscopies such as IR and Raman are nondestructive analysis tools of in situ chemistry at interfaces but when considering monolayers or less, they may suffer from their lack of sensitivity to discriminate between “bulk” and “surface-adsorbed” molecules. Nonlinear optics and especially Two-Colour Sum-Frequency Generation (2C-SFG) spectroscopy offer a solution to overcome this issue. As will be shown in this presentation, after establishing the main principles governing this specific technique, 2C-SFG can be applied to address fundamental questions related to heterogeneous chemistry, interfacial electrochemistry, catalysis and more recently nanomaterials. In fact, the particular selection rules of this vibro-electronic spectroscopy give access to unique and complementary information with respect to the traditional optical investigation probes.
ABOUT THE PRESENTER
Christophe Humbert received his PhD in Physics (2003) at the University of Namur (Belgium) where he developed and applied the pioneering nonlinear optical technique named Two-Colour Sum-Frequency Generation spectroscopy (2C-SFG) of interfaces. After a post-doctoral stay (2004) at the LURE synchrotron Facility (Orsay, France) where he performed the first measurements with SFG spectroscopy at the surfaces of functionalized gold nanoparticles adsorbed on SiO2 substrates, he was recruited as a CNRS Researcher in 2006 in the Laboratoire de Chimie Physique (LCP, Orsay). He obtained his Habilitation (HDR) in Physics (2014) at the University of Paris-Sud. He is head of the TEMiC (Transfert d’Electrons en Milieu Condensé) Scientific Group (16 permanent researchers) and the experimental platform of nonlinear optical spectroscopy coupled to the CLIO Free Electron Laser European Facility in Orsay with which he highlighted for the first time by SFG the Pt-C extramolecular vibration mode at the CO/Pt(110) interface (2011). He is now working on the fundamental optical properties of (bio)chemical sensors based on nanostructured platforms built on metallic and semiconducting nanoparticles.
Tea/coffee will be available at 09h45
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