Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)
O 35.49: Poster
Dienstag, 27. März 2012, 18:15–21:45, Poster B
Molecular beam studies of methane dissociation on Ru(0001) — •Harald Kirsch, Zefeng Ren, R. Kramer Campen, and Martin Wolf — Fritz-Haber-Institut , Abt. Physikalische Chemie, Faradayweg 4-6, 14195 Berlin
Understanding the dissociation of methane on transition metal surfaces is a challenge in heterogeneous catalysis. We have investigated the dissociation products of CH4 and CD4 on a Ru(0001) surface with vibrational sum-frequency spectroscopy (SFG) and temperature-programmed desorption(TPD). To overcome the dissociation barrier under UHV conditions, a supersonic molecular beam of CH4/CD4 seeded in He or H2 has been used to generate adsorbed methyl radicals. The system was studied as function of surface temperature (300K - 500K) and coverage. Coverage was determined after each measurement by oxygen coadsorption and recombinative C + O desorption. High resolution (<5 cm−1) vibrational sum-frequency generation spectroscopy has allowed the observation of new features in the C-H stretching region. For adsorption at surface temperatures below 350K just one resonance could be observed at 3000 cm−1, which is identified as the CH stretching mode. At temperatures higher than 350K, two additional red shifted peaks appear. These observation could help to identify intermediates of the methane dehydrogenation and complement previously discovered decomposition pathways.