Regensburg 2013 – scientific programme
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O: Fachverband Oberflächenphysik
O 10: Nanostructures at Surfaces I
O 10.4: Talk
Monday, March 11, 2013, 11:15–11:30, H45
Electron quantization in arbitrarily shaped Au islands on MgO thin films — •Christian Stiehler1, Yi Pan1, Wolf-Dieter Schneider1, Pekka Koskinen2, Hannu Häkkinen2, Niklas Nilius Nilius1,3, and Hans-Joachim Freund1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany — 2Departments of Physics and Chemistry, Nanoscience Center, University of Jyväskylä, P.O. Box 35 (YFL), FI-40014 Finland — 3Carl von Ossietzky Universität Oldenburg, Institut für Physik, D-26111 Oldenburg, Germany
Electron quantization is a fundamental phenomenon that accompanies the transition from bulk metals to nanoclusters. The associated opening of a gap at the Fermi level crucially affects various properties of the nanostructure, e.g. its electrical and optical behavior and its performance in catalytic reactions [1]. By using low-temperature STM and STS, we have investigated the electronic structure of differently shaped 2D Au islands grown on MgO/Ag(001) thin films, concentrating on the size regime of the metal-insulator transition that occurs between 50-200 atoms in gold clusters. The observed symmetries and energy positions of quantum well states were rationalized by simple analytical models as well as by a density-functional-tight-binding approach that accounts also for structural disorder in the islands. Based on a statistically relevant number of single-cluster experiments, we derived general conclusions on the size of the HOMO-LUMO gap as a function of atom count and symmetry of the metal nanostructures.
[1] M. Valden, X. Lai, D. W. Goodman, Science 281, 1647 (1998)