Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 34: Focused Session: Epitaxial Graphene IV

O 34.5: Vortrag

Mittwoch, 25. März 2009, 12:00–12:15, SCH 251

Pt and other transition metal cluster lattices on graphene — •Timm Gerber, Alpha T. N'Diaye, Rabia Djemour, Johann Coraux, Carsten Bussse, and Thomas Michely — II. Physikalisches Institut, Universität zu Köln

Highly ordered arrays of Ir Clusters had been obtained by depositing Ir on a Ir(111) surface covered with a graphene monolayer. The periodicity of these arrays is determined by the moiré pattern of graphene on Ir(111). [1]

In order to show that other materials form clusters on the same substrate we deposited Pt, W and Re instead of Ir. Pt is of great interest due to its catalytic properties. The optimum deposition temperature varies for each deposit: At room temperature, we obtained highly ordered cluster lattices of Pt as well as of W. Pt clusters are stable up to 500K. By evaporating Re at 200K we obtained as well highly ordered lattices which were stable at room temperature.

Based on the binding mechanism of the clusters to graphene -- local diamond formation between the cluster and the substrate -- we propose criteria for the ability of a material to form a cluster lattice. These involve the cohesive strength, the lattice parameter and the valence orbital radius of the deposit.

[1] A. T. N'Diaye et al. PRL 97, 215501 (2006)