Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 62: Surface chemical reactions II
O 62.1: Vortrag
Freitag, 27. März 2009, 11:15–11:30, SCH A01
In-situ investigation of sulfur oxidation on a stepped Pt surface — •Regine Streber1, Christian Papp1, Michael Peter Andreas Lorenz1, Andreas Bayer1, Reinhard Denecke2, and Hans-Peter Steinrück1 — 1Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen — 2Willhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstr. 2, 04103 Leipzig
We studied the reaction of oxygen with preadsorbed sulfur on the stepped Pt(355) surface by in-situ high-resolution XPS applying synchrotron radiation at BESSY II. The reactivity strongly depends on surface temperature. At 250 K, dosing of molecular oxygen on the partially sulfur precovered surface leads to the coadsorption of atomic S and O, but almost no reaction, as concluded from the S 2p spectra. Upon heating this mixed layer to elevated temperatures, the subsequent formation of two new species is observed, which are assigned to SO2 and SO4. At 300 K, dosing of oxygen results in the partial formation of SO2, while at 350 K a consecutive reaction to SO4 occurs. To determine the kinetic parameters of these reactions, the oxidation has been studied at different temperatures. In addition, the influences of the initial sulfur precoverage and of the oxygen pressure have been investigated. This word was supported by BMBF (05 ES3XBA/5) and the DFG through the Cluster of Excellence "Engineering of Advanced Materials".