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 35.8: Poster
Dienstag, 27. März 2012, 18:15–21:45, Poster B
Combined experimental STM and atomistic KMC modelling study of Ru cluster growth on graphene/Ru(0001) — •Albert K. Engstfeld1, Christoph U. Lorenz1, Harry E. Hoster2, Yong Han3, Jim W. Evans3, and R. Jürgen Behm1 — 1Ulm University, Institute of Surface Chemistry and Catalysis, D-89069 Ulm, Germany — 2Technische Universität München, Centre for Electromobility, 50 Nanyang Drive, Singapore 637553 — 3Iowa State University, IPRT and Department of Physics & Astronomy, Ames, IA 50011 USA
The inhomogeneous potential energy surface (PES) for Ru on graphene/Ru(0001) leads to the formation of Ru clusters on specific trap sites within the moiré unit cells. We determine the fraction of populated moiré cells (versus coverage, deposition flux, and temperature), as well as the spatial distribution of clusters quantified by a SRO analysis. Behaviour is elucidated by KMC simulations of an atomistic model for cluster formation on a suitable non-uniform PES. The simulated evolution of the cluster density versus coverage, and the spatial cluster distribution, agree with experiments. An unusually weak dependence on deposition flux seen in experiment is not yet recovered by the current simulation parameters. Simulation also provides the cluster size distribution, not readily accessible with STM. Varying diffusion barriers for Ru used in the simulation are compatible with DFT results for Ru on flat graphene.