Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 36: Postersitzung (Elektronische Struktur, Grenzfl
äche fest-flüssig, Halbleiteroberfl
ächen und -grenzfl
ächen, Nanostrukturen, Oberfl
ächenreaktionen, Teilchen und Cluster, Struktur und Dynamik reiner Oberfl
ächen)

O 36.72: Poster

Montag, 7. März 2005, 15:00–18:00, Poster TU F

Photoelectron spectra of quantized states on cluster facets — •I. Barke, T. Irawan, and H. Hövel — Experimentelle Physik I, Universität Dortmund, D-44221 Dortmund

Gold clusters grown on prestructured Highly Oriented Pyrolytic Graphite (HOPG) have been investigated by Scanning Tunneling Spectroscopy (STS) and Ultraviolet Photoelectron Spectroscopy (UPS). In earlier STS studies the pronounced patterns of standing waves in the dI/dV maps measured on the top facets of large Au clusters have been identified with a Shockley surface state confined to the facet area [1]. Here we present new results of combined UPS and STM studies using the same sample which are discussed in the context of the respective characteristics of the experimental methods. Spatial (UPS) and momentum (STS) averaging is taken into account explicitly, as well as the dynamic final state effect in the photoemission process [2]. Quantized states could now be clearly observed not only in the STS curves, but also in angle resolved UPS (ARUPS) measurements of the same cluster sample. Utilizing a sophisticated deconvolution technique based on the Maximum Entropy Method (MEM) we achieve a unified description of the different spectra.

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

[2] H. Hövel, I. Barke, H.-G. Boyen, P. Ziemann, M.G. Garnier, P. Oelhafen, Phys. Rev. B 70, 045424 (2004).