Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 41: Poster Session I (Semiconductor Substrates: Epitaxy and growth; Semiconductor Substrates: Adsorbtion; Semiconductor Substrates: Solid-liquid interfaces; Semiconductor Substrates: Clean surfaces; Oxides and insulators: Epitaxy and growth; Oxides and insulators: Adsorption; Oxides and insulators: Clean surfaces; Organic, polymeric and biomolecular films - also with adsorbates; Organic electronics and photovoltaics, Surface chemical reactions; Heterogeneous catalysis; Phase transitions; Particles and clusters; Surface dynamics; Surface or interface magnetism; Electron and spin dynamics; Spin-Orbit Interaction at Surfaces; Electronic structure; Nanotribology; Solid/liquid interfaces; Graphene; Others)

O 41.111: Poster

Dienstag, 23. März 2010, 18:30–21:00, Poster B1

Adsorption of diatomic halogen molecules on graphene — •Alexander N. Rudenko^1,2, Frerich J. Keil¹, and Alexander I. Lichtenstein² — ¹Technische Universität Hamburg-Harburg, Institut für Chemische Reaktionstechnik, Eißendorfer str. 38, 21073 Hamburg, Germany — ²Universität Hamburg, Institut für Theoretische Physik, Jungiusstraße 9, 20355 Hamburg, Germany

We investigate the adsorption of fluorine, chlorine, bromine, and iodine diatomic molecules on graphene using density-functional theory taking into account nonlocal correlation effects by means of vdW-DF approach. It is shown that the van der Waals interactions play a crucial role in the formation of chemical bonding between graphene and halogen molecules, and therefore important for a proper description of adsorption in this system. Adsorption energies are found to be up to an order of magnitude larger than the values obtained using standard semilocal functionals without vdW corrections. In the cases of F₂ and I₂ we also found a considerable ionic contribution to the binding energy, slowly vanishing with the distance. The analysis of the electronic structure shows that ionic interaction arises due to the charge transfer from graphene to the molecules. In addition, graphite intercalation by halogen molecules have been investigated. It is found that the binding energy of graphite layers becomes significantly weaker in the presence of halogen molecules, which agrees with the results of recent experiments on sonochemical exfoliation of intercalated graphite.