Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)

O 35.64: Poster

Dienstag, 27. März 2012, 18:15–21:45, Poster B

Linear and nonlinear spectroscopy of size selected metal clusters on surfaces — •Philipp Heister, Tobias Lünskens, Martin Tschurl und Uli Heiz — Technische Universität München, Lehrstuhl für physikalische Chemie

The catalytic activity of small metal clusters has been shown to vary by orders of magnitude upon addition of a single metal atom. A better understanding of the interplay between the electronic and geometrical structure and the catalytic activity of the clusters may be gained through a precise knowledge of the electronic structure and geometry from spectroscopic studies. Therefore we use different spectroscopic methods to investigate size selected and unselected metal clusters on surfaces under UHV conditions. We use highly sensitive techniques such as surface Cavity Ring-Down spectroscopy (s-CRD) and surface Second-Harmonic-Generation spectroscopy (s-SHG) for observing the obtical properties of these clusters. The interest mainly focuses on the size and shape dependent electronic structures and plasmon-like transitions of small deposited clusters. With these plasmon oscillations we are able to gain further information about oxidation and reduction of the supported size selected clusters. We also observe interesting cluster-plasmon size effects, for example a sudden increase in plasmon resonances (parallel to the surface normal) for increasing cluster size. It seems that these clusters need to be at least three atomic layers thick in order to show plasmon oscillations, whereas thinner clusters (one or two atomic layer) do not show any plasmon oscillations.