Regensburg 2004 – scientific programme

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O: Oberflächenphysik

O 43: Adsorption an Oberflächen IV

O 43.3: Talk

Friday, March 12, 2004, 11:45–12:00, H36

Activated adsorption of ethane on Pt(111) studied by in-situ high resolution XPS — •T. Fuhrmann, M. Kinne, J.F. Zhu, B. Tränkenschuh, R. Denecke, and H.-P. Steinrück — Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen

As less reactive basic materials used in chemical industries, alkanes need in general catalysts to reduce the activation energies for dissociation. The first elementary step is the adsorption on the catalysts surface. Under UHV conditions, alkanes show a strong kinetic energy dependence of their sticking probability on metal surfaces. Using the combination of a molecular beam and high resolution XPS at the synchrotron facility BESSY II, we study the species evolving during the adsorption process. Time resolved measurements allow to determine the adsorption kinetics. Depending on the surface temperature and the parameters of the impinging molecules, both molecular as well as dissociative adsorption channels are observed. For direct dissociation the same surface species is observed for all beam parameters used. Using temperature programmed XPS (TPXPS), the thermal evolution of the adsorbed species is studied. Before reaching pure carbon by complete dehydrogenation, different intermediates are identified by their C1s binding energies and their vibrational fine structure. Supported by the DFG (STE 620/4-2).