Regensburg 2002 – wissenschaftliches Programm

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SYCO: Cluster auf Oberflächen

SYCO 1: Electronic Properties

SYCO 1.2: Hauptvortrag

Donnerstag, 14. März 2002, 11:45–12:15, H 36

Geometric and electronic structure of size-selected supported clusters — •Christian Félix — Institut de Physique des Nanostructures, FSB, Ecole Polytechnique Fédérale, CH-1015 Lausanne, Switzerland

The deposition of clusters in a rare gas matrix support allows the accumulation of reasonable amounts of dilute material in an inert environment to study their properties. In small systems there is a strong interaction between their geometric and the electronic structure, we are therefore interested in both. With resonant Raman spectroscopy, we have shown that we can get a vibrational information even on small amounts of material; comparing this information to quantum calculations it is possible to gain a geometrical information.

Although the electronic structure of metal clusters has already been studied intensively, we have recently discovered the fluorescence of small silver clusters embedded in a gas matrix. The picture that needs to be confirmed by further investigations is the following: Optically excited states relax vibrationally to a long lived state, from which the fluorescence can occur. The matrix-support allows for the rapid vibrational coupling and prevents the dissociation. There is an analogy with bulk semiconductors, where the excitation of an electron from the valence to the conduction band is followed by a rapid phononic relaxation to the lower edge of the conduction band, from where the fluorescence can occur.