Dresden 2006 – wissenschaftliches Programm
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O: Oberflächenphysik
O 14: Poster session I (Adsorption, Epitaxy and growth, Phase transitions, Surface reactions, Organic films, Electronic structure, Methods) (sponsored by Omicron Nanotechnology GmbH)
O 14.6: Poster
Montag, 27. März 2006, 18:00–21:00, P2
Probing complex adsorption structures: A joint experimental and theortical study — •Jan Haubrich1, David Loffreda2, Françoise Delbecq2, Philippe Sautet2, Alexander Krupski1, Conrad Becker1, and Klaus Wandelt1 — 1Inst. f. Phys. u. Theo. Ch., Wegeler. 12, D-53115 Bonn — 2Lab. de Chimie, UMR CNRS 5182, ENS Lyon, 46 Allée d’Italie, F-69364 Lyon Cedex 07
Studies on catalysis such as the selective hydrogenation of α,β-unsaturated aldehydes on transition metal surfaces represent a challenge to both experimentalists and theoreticians. Although numerous studies have been dedicated to systems like acrolein or prenal on Pt(111) in recent years, the details of the molecule-surface bonding still remain under debate. Yet the selectivities of such processes depend crucially on the adsorption complexes. Their characterization is even more complicated when alloy surfaces are considered because alloying is often used to optimize the properties of the catalyst. We here present a joint experimental and theoretical study on molecule-surface bonding of prenal on Pt(111) and two Pt-Sn surface alloys based on the interpretation of HREEL spectra using ab initio density-functional theory (DFT). HREELS experiments carried out on the three model-catalysts show highly complex spectra of the adsorbed prenal at low temperatures. Combining the HREEL spectra with the results of the vibrational analysis obtained from the DFT calculations, we are able to identify stable adsorption geometries, interpret the normal modes corresponding to the measured loss peaks and to point to likely reaction intermediates.