Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 23: Nanostructures at surfaces: Dots, particles, clusters
O 23.2: Vortrag
Dienstag, 23. März 2010, 10:45–11:00, H33
Identifying low-coordinated atoms on oxide-supported Au clusters — Xiao Lin1, •Niklas Nilius1, Pekka Koskinen2, Hannu Häkkinen2, and Hans-Joachim Freund1 — 1Fritz-Haber-Institut der MPG, Faradayweg 4-6, D-14195 Berlin, Germany — 2Department of Physics, University of Jyväskylä, P.O. Box 35, FI-40014 Finland
The outstanding chemical properties of small metal particles are partly governed by the perimeter atoms that are located at the boundary to the oxide support. Those edge and corner sites are unique due to their low coordination, a peculiar electronic structure and charge state. We have employed STM and DFT to characterize the perimeter atoms around planar Au clusters grown on a MgO/Ag(001) thin film. The atoms exhibit an enhanced state density with respect to the island center in conductance spectra taken around the Fermi level. Furthermore, they carry extra electrons resulting from a charge transfer from the MgO-Ag interface into the Au islands. Both effects render the perimeter atoms highly attractive for binding molecules, as demonstrated via CO adsorption experiments on the system.