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O: Oberflächenphysik

O 46: Adsorption an Oberfl
ächen V

O 46.9: Vortrag

Dienstag, 8. März 2005, 17:45–18:00, TU EB420

CO adsorption on stepped Pt(355) and Pt(644) - the dissimilar twins — •Reinhard Denecke, Barbara Tränkenschuh, Thomas Fuhrmann, Christian Papp, Junfa Zhu, and Hans-Peter Steinrück — Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen

The adsorption and thermal desorption of CO on stepped Pt surfaces was studied by the combination of a supersonic molecular beam and in-situ high resolution XPS. Using synchrotron radiation as excitation source, we are able to clearly distinguish between adsorption sites at steps and at terraces in C 1s spectra, even at fast measuring times (about 4 s per spectrum). Both surfaces studied contain five atom wide (111) terraces separated by monatomic steps. While on Pt(355) these steps have (111) orientation, they are in (100) orientation on Pt(644). Interestingly, these very similar surfaces exhibit differences in CO adsorption behaviour not only at step sites, as expected, but also on the nominally equal terraces. Here, the distribution between bridge and on-top bound species on Pt(644) is quite similar to the situation found for Pt(111)[1], whereas for the (355) surface the adsorbate-adsorbate interactions modify the occupation ratio significantly. Thus, an influence on surface reactions such as the CO oxidation, can be expected. Supported by the DFG (STE 620/4-2). [1] M. Kinne et al., J. Chem. Phys. 117, 10852 (2002).