Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 55: Poster Session III - MA 141/144 (Methods: Atomic and Electronic Structure; Particles and Clusters; Heterogeneous Catalysis; Semiconductor Substrates: Epitaxy and Growth+Adsorption+Clean Surfaces+Solid-Liquid Interfaces; Oxides and Insulators: Solid-Liquid Interfaces+Epitaxy and Growth; Phase Transitions; Metal Substrates: Adsorption of Inorganic Molecules+Epitaxy and Growth; Surface Chemical Reactions; Bimetallic Nanosystems: Tuning Physical and Chemical Properties; Oxides and insulators: Adsorption; Organic, polymeric, biomolecular films; etc.)
O 55.39: Poster
Mittwoch, 27. Februar 2008, 18:30–19:30, Poster F
Energy barriers for dissociative adsorption of H2 molecules on Si, SiC, and diamond (001) surfaces: A comparison — •Xiangyang Peng1, Peter Krüger2, and Johannes Pollmann2 — 1Department of Physics, Uppsala University, SE-75121 Uppsala, Sweden — 2Institut für Festkörpertheorie, Wilhelm-Klemm-Str. 10, 48149 Münster
We report first-principles investigations of the reaction of molecular hydrogen with the Si(001)-(2×1) and C(001)-(2×1) surfaces and discuss the results in light of our previous studies of H2 reaction with two different SiC(001) surfaces, one of which is highly reactive to H2 uptake. The calculations reveal that the reaction of H2 with all above surfaces depends crucially on intricate combined effects of the substrate lattice constant, the arrangement of the surface dimers as well as the orientation and spatial extent of their dangling bond orbitals. In agreement with experiment, our results confirm that Si(001) and C(001) are inert to H2 adsorption at room temperature because all adsorption pathways considered exhibit substantial energy barriers. They are in satisfying agreement with previous density functional and quantum Monte Carlo calculations which have been carried out for two specific reaction pathways only. Guided by our earlier studies on H2 reaction with SiC(001) surfaces, we have considered a third reaction pathway which actually turns out to have the lowest energy barrier on C(001). A comparison of the energy barriers and reaction energies for the different surfaces addressed turns out to be particularly revealing.