Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)

O 44.52: Poster

Mittwoch, 28. März 2007, 17:00–19:30, Poster C

CO oxidation on modified Pt surfaces — •Regine Streber, Barbara Tränkenschuh, Michael Lorenz, Christian Papp, Reinhard Denecke, and Hans-Peter Steinrück — Lehrstuhl für Physikali-sche Chemie II, Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen

In order to get closer to realistic systems, we studied the CO oxidation reaction not only on Pt(111) [1] but also on stepped Pt surfaces. We investigated the reaction between adsorbed atomic oxygen and CO on Pt(355) and Pt(322), which both have (111) oriented terraces with a width of five atomic rows but different step orientations, (111) vs. (100), respectively. Time-dependent in situ XP spectra in the O 1s and C 1s binding energy region showed that the reaction rate is increased on the stepped surfaces and depends on the step orientation. The preadsorbed atomic oxygen occupies different adsorption sites on both surfaces with different saturation coverages, leading to interesting temperature-dependent phenomena. In order to obtain a more detailed insight, we modified the system by deposition of Ag, which grows in rows along the lower step edges [2]. In this way the oxygen distribution can be modified. However, since higher CO coverages move Ag atoms away from the step edges to form islands on the terraces, the influence of Ag rows can only be studied for the initial period of the oxidation reaction.

The work was supported by the DFG (Ste 620/4-3).

[1] Kinne et al., J. Chem. Phys. 120 (2004) 7113.

[2] Gambardella et al., Phys. Rev. B 61 (2000) 2254.