Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 59: Poster Session II (Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: arrays; Nanostructures at surfaces: Wires, tubes; Nanostructures at surfaces: Other; Plasmonics and nanooptics; Metal substrates: Epitaxy and growth; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsoprtion of organic / bio molecules; Metal substrates: Adsoprtion of inorganic molecules; Metal substrates: Adsoprtion of O and/or H; Metal substrates: Clean surfaces; Density functional theory and beyond for real materials)
O 59.99: Poster
Mittwoch, 24. März 2010, 17:45–20:30, Poster B1
Adsorption of CO on clean and oxidized Pt3Ti(111) — •Marco Moors1, Séverine Le Moal2,3, Jan Markus Essen1, Conrad Becker2, and Klaus Wandelt1 — 1Institut für phys. und theoret. Chemie, Universität Bonn — 2Centre Interdisciplinaire de Nanoscience de Marseille — 3Technische Universität München
The adsorption of CO on Pt3Ti(111) before and after its oxidation has been investigated by AES, TDS, LEED and HREELS. The adsorption of CO has clearly been evidenced on clean Pt3Ti(111). The LEED patterns exhibit either a diffuse or a sharp c(4x2) structure (stable up to 300 K) attributed to CO depending on the adsorption temperature. Remarkably, the adsorption / desorption behavior of CO on clean Pt3Ti(111) exhibits similarities to that previously reported for CO on Pt(111). Our results clearly evidence a partial CO decomposition on Ti sites and molecular adsorption of CO on on-top Pt sites. Therefore, the clean surface can not be terminated by a pure Pt plane as previously discussed in the literature. Lowly oxidized Pt3Ti(111) surfaces (< 135 L O2 exposure at 1000 K) exhibit a CO adsorption / desorption behavior similar to that of the clean surface with again a c(4x2) structure (stable up to 250 K) attributed to CO adsorption. These results indicate that some areas of the substrate remain non-oxidized upon low oxygen exposures. Highly oxidized and therefore completely oxide covered Pt3Ti(111) surfaces (> 220 L O2 exposure at 1000 K) allow no CO adsorption at sample temperatures over 100 K.