Regensburg 2004 – wissenschaftliches Programm
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O: Oberflächenphysik
O 14: Postersitzung (Adsorption an Oberflächen, Epitaxie und Wachstum, Organische Dünnschichten, Oxide und Isolatoren, Phasenübergänge, Rastersondentechniken, Struktur und Dynamik reiner Oberflächen)
O 14.15: Poster
Montag, 8. März 2004, 18:00–21:00, Bereich C
Adsorption and Dissociation of Methanol on Pd(111) — •A. Bayer, J. Pantförder, S. Pöllmann, D. Borgmann, R. Denecke, and H.-P. Steinrück — Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstr. 3, D-91058 Erlangen
Methanol adsorbed on a Pd(111) surface at 100 K dissociates upon annealing mainly to CO and H, with methoxy as an intermediate. The investigation of this reaction by high resolution X-ray photoelectron spectroscopy (XPS) with monochromized Al Kα radiation is complicated because of two reasons: First, the C 1s binding energy differences between methanol, methoxy, and CO are too small to discriminate between different species [1]. Second, the O 1s binding energy region is superposed by the broad substrate Pd 3p3/2 peak. To overcome the latter problem, the Pd 3p3/2 peak of the clean surface was subtracted from the measured spectra after intensity correction via the Pd 3p1/2 peak. In addition, the surface sensitivity was enhanced by choosing a grazing emission angle. The resulting difference spectra show discrete O 1s peaks with binding energy differences of 0.2-1.4 eV for the different species. Additional measurements by ultraviolet photoelectron spectroscopy (UPS) and temperature programmed desorption (TPD) allow the assignment to methanol, methoxy, and CO.
Supported by the DFG (Schwerpunktsprogramm 1091, Ste620/3-3).
[1] M. Rebholz and N. Kruse, J. Chem. Physics 95 (1991) 7745.