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O: Oberflächenphysik

O 19: Teilchen und Cluster II

O 19.5: Vortrag

Dienstag, 9. März 2004, 12:15–12:30, H39

Spectroscopy of gold clusters on graphite for a broad range of cluster sizes — •I. Barke, T. Irawan, and H. Hövel — Universität Dortmund, Experimentelle Physik I, D-44221 Dortmund

Gold clusters grown on nanostructured highly oriented pyrolytic graphite (HOPG) have been investigated by Scanning Tunneling Spectroscopy (STS) and Ultraviolet Photoelectron Spectroscopy (UPS). The evolution of the d electron UPS spectra for increasing cluster size is consistent with corresponding Scanning Tunneling Microscopy (STM) results. The combination of these methods allows a semi quantitative analysis of the cluster growth process. The main emphasis lies on the change of the cluster morphology from small clusters without facets to large faceted clusters. In addition, we present STS results for a wide variety of cluster sizes. On the (111) facets of large Au clusters (N ≈ 10⁴ atoms) STS and UPS spectra revealed a two dimensional cluster surface state confined to the cluster facet [1, 2]. Further on, we measured dI/dV spectra for about 70 different smaller clusters (N ≈ 10¹ … 10³ atoms). Though these series of STS curves look more complicated, we observed spectral features changing systematically with the cluster size.

[1] I. Barke, H. Hövel, Phys. Rev. Lett. 90, 166801 (2003).

[2] H. Hövel, I. Barke, New J. Phys. 5, 31 (2003).