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 14.5: Poster

Montag, 27. März 2006, 18:00–21:00, P2

Influence of Ag on the CO adsorption and desorption behavior on Pt(644) — •Regine Streber, Barbara Tränkenschuh, 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 Ag on the interaction of CO with a stepped Pt(644)=[5(111)x(100)] surface was studied by using in-situ high-resolution X-ray photoelectron spectroscopy. AES studies indicate that the growth of Ag on stepped platinum surfaces follows a Stranski-Krastanov mechanism [1]. For small (< 0.5 ML) Ag coverages, a row-by-row growth mode has been reported for deposition at 300 K [2]. Besides studying the Ag growth by taking XP spectra in the Ag 3d and Pt 4f binding energy regions, we determined its influence on the CO adsorption behavior by quantitative analysis of time-dependent C 1s spectra. For a silver coverage resulting in monatomic chains along the steps, the total CO coverage at 130 K is mainly associated with the Pt terraces but almost as large as for clean Pt(644) terraces, inspite of the Ag decoration; however, the ratio between CO bonded to on-top and bridge sites decreases. Interestingly, when heating the resulting layers, the C 1s signal related to CO step adsorption is reappearing between 300 and 400 K. The desorption behavior of CO and Ag is also studied by TPD.

[1] P.W. Davies et al., Surf. Sci. 121 (1982) 290.

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