Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)
O 44.54: Poster
Mittwoch, 28. März 2007, 17:00–19:30, Poster C
The influence of surface oxygen and oxide layers on adsorption systems on Ni(111) — •Michael Peter Andreas Lorenz, Regine Streber, Fabian Bebensee, Reinhard Denecke, and Hans-Peter Steinrück — Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen
During many surface reactions, especially under realistic conditions, oxygen layers and even surface oxides form. We have studied the influence of such surface modifications at Ni(111) on the adsorption of small molecules, such as CO2 and CH4. Using in-situ x-ray photoelectron spectroscopy at BESSY II we characterized these oxygen layers by means of O 1s and Ni 2p core levels. In order to facilitate dissociative methane adsorption, we provided molecules with a well-defined kinetic energy (up to 0.8 eV) using a supersonic molecular beam. Interestingly, both the saturated oxygen adlayers as well as a surface Nickel oxide completely prevent dissociative methane adsorption for all energies studied. On the other hand, the physisorption regime seems to be shifted to higher temperatures as compared to clean Ni(111). The same seems to be true for CO2, which also shows enhanced physisorption in the presence of oxygen.