Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 53: Nanostructures at surfaces: Dots, particles, clusters III
O 53.13: Vortrag
Donnerstag, 26. März 2009, 18:00–18:15, SCH A215
Energy dissipation during hyperthermal deposition of non-IPR fullerenes on HOPG — Stefan-Sven Jester, Daniel Löffler, Patrick Weis, •Artur Böttcher, and Manfred Kappes — Institut für Physikalische Chemie, Universität Karlsruhe, 76131 Karlsruhe, Germany
Low energy cluster beam deposition, LECBD, has been used to generate thin films comprising monodisperse non-IPR fullerenes, Cn, 50<n<60, on HOPG. The topography of the resulting Cn films has subsequently been studied by AFM. Deposition experiments were carried out at hyperthermal incident kinetic energies, E0 (1-40 eV) and elevated surface temperatures Ts (300-700 K). Initial sticking of Cn cages is governed by the lateral density of step edges, which act as pinning and nucleation centers for migrating cages. Thus, in the early deposition stages, the surface exhibits large areas of empty terraces, while the step edges themselves are well-decorated. The terraces in turn become decorated by dendritic Cn islands in later deposition stages. Both, the mean size of these 2D islands and the mean distance between nearest islands, δ, scale with the size of the terraces. When increasing the primary kinetic energy, the fractal-like islands become smaller and less dendritic in shape. The mean initial sticking coefficient decays exponentially with increasing E0. Instead of the dendritic islands generated at room temperature, densely packed islands terminated by smooth rims are observed at elevated temperatures. The findings are rationalized by a model which describes the friction-conditioned energy losses in the sliding movement of the cages on terraces.