Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 62: Graphene III
O 62.1: Vortrag
Donnerstag, 25. März 2010, 10:30–10:45, H31
Structural properties and site specific interactions of Pt with the graphene/Ru(0001) moiré overlayer — Kerstin Donner, Martin Willenbockel, and •Peter Jakob — Fachbereich Physik, Philipps-Universität Marburg, Germany
The growth, structure, and adsorptive properties of graphene on Ru(0001) has been investigated in detail [1]. Thereby the coherence of graphene layers on Ru(0001) over extended distances has been employed to discriminate between A and B types of Ru(0001) steps and to identify fcc as well as hcp regions of the associated moiré superstructure. We demonstrate that the individual regions of the graphene/Ru(0001) overlayer exhibit pronounced variations in interaction strengths with deposited metal atoms, recommending this substrate to serve as a template for growing periodic arrays of uniform nanoislands. In fact Pt clusters have been grown at 140-180 K and they are found to organize in a well-ordered periodic array defined by the moiré superlattice. Their preferred location within the graphene/Ru(0001) moiré unit cell is identified to be the fcc region. Pt islands are found to be structurally stable at room temperature; they may, however, exhibit some distinct frizzyness which is attributed to some of the islands consisting of stable cores with one or two weakly bound Pt atoms additionally attached to them. Occasionally, pick-up or lateral displacement of Pt islands by the STM tip is observed, which can be avoided by working at tunneling resistances RT > 109 Ω and tunneling currents IT < 50 pA.
[1] K. Donner and P. Jakob, J. Chem. Phys. 131 (2009) 164701.