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O: Oberflächenphysik

O 3: Adsorption I

O 3.2: Vortrag

Montag, 27. März 2006, 11:30–11:45, TRE Phys

Changes in CO adsorption behavior on stepped platinum surfaces induced by preadsorbed silver — •Barbara Tränkenschuh, Regine Streber, Johannes Schöck, Christian Papp, Reinhard Denecke, and Hans-Peter Steinrück — Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen

The influence of preadsorbed silver on the adsorption of CO on stepped platinum surfaces was studied using a combination of high-resolution X-ray photoelectron spectroscopy (XPS) and a supersonic molecular beam set-up. Gambardella et al. [1] have shown that on stepped Pt surfaces silver grows via an 1D row-by-row growth mode for small coverages (< 0.5 ML), starting at the step edges. In our study we deposited different amounts of silver onto Pt(355)=[5(111)x(111)] and Pt(644)=[5(111)x(100)] at 300 K and monitored the growth behavior by XPS in the Ag 3d and Pt 4f binding energy region. Thereafter, CO was dosed at low temperatures and simultaneously C 1s spectra were measured to determine the time-dependent occupation of the different adsorption sites, which can be distinguished by high-resolution XPS. For Ag coverages up to one monatomic row at the step edges, mainly the occupation of the CO step adsorption sites is changed. For higher Ag coverages, also changes in the CO adsorption behavior on the terraces were observed, due to the decreasing free Pt terrace width. Supported by the DFG (STE 620/4-3).

[1] P. Gambardella et al., Physical Review B 61 (2000) 2254.