Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 42: Poster Session II (Nanostructures at surfaces: arrays; Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: Other; Nanostructures at surfaces: Wires, tubes; Metal substrates: Adsorption of O and/or H; Metal substrates: Clean surfaces; Metal substrates: Adsorption of organic/bio moledules; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsorption of inorganic molecules; Metal substrates: Epitaxy and growth; Heterogeneous catalysis; Surface chemical reactions; Ab-initio approaches to excitations in condensed matter; Organic, polymeric, biomolecular films– also with adsorbates; Particles and clusters)
O 42.119: Poster
Mittwoch, 25. März 2009, 17:45–20:30, P2
Electronic properties of size selected Ag clusters on C60 and HOPG surfaces — •Ben Wortmann1, Stefanie Duffe1, Lukas Patryarcha1, Bernd von Issendorff2, and Heinz Hövel1 — 1Technische Universität Dortmund, Experimentelle Physik I, 44221 Dortmund, Germany — 2Universität Freiburg, Fakultät für Physik, Hermann-Herder Straße 3, 79104 Freiburg, Germany
We deposited mass selected Ag clusters, which are expected to form geometrically magic icosahedra, on 1.5 ML C60/HOPG at low temperatures. On 1 and 2 ML C60 we observed very narrow cluster height distributions for Ag309± 3 and Ag923± 9. The clusters on 1 and 2 ML C60 kept their original height for more than 12 hours at room temperature [1, 2]. To get information on the electronic structure of the clusters, scanning tunnelling spectroscopy measurements were performed at 5 K for Ag309± 3 and Ag923± 9/C60/HOPG. We observed spectra with identical features for individual clusters with the same selected size. Additionally we investigated the electronic properties of size selected clusters with ultraviolet photoemission spectroscopy (UPS). Using C60 as buffer layer for the cluster deposition, the dominant UPS signal of C60 masks the signal of the clusters. For this reason the Ag clusters were deposited and investigated on bare HOPG at 100 K. The low temperature decreases the mobility of the clusters on HOPG and reduces coalescence. One aim of these studies is the comparison to UPS spectra of size selected clusters in free beam [3].
[1] S. Duffe et al., EPJD 45, 3 (2007) [2] S. Duffe et al., submitted for publication [3] O. Kostko et al., PRL 98, 043401 (2007)