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DS: Fachverband Dünne Schichten

DS 29: Nanoengineered Thin Films II

DS 29.1: Vortrag

Donnerstag, 26. März 2009, 11:15–11:30, GER 37

Geometric properties and thermal stability of size selected Ag clusters on C₆₀ films — •Stefanie Duffe¹, Lukas Patryarcha¹, Ben Wortmann¹, Bernd von Issendorff², Michael Moseler^{2, 3, 4}, and Heinz Hövel¹ — ¹TU Dortmund, Experimentelle Physik I, 44221 Dortmund, Germany — ²Universität Freiburg, Fakultät für Physik, 79104 Freiburg, Germany — ³Fraunhofer Institut für Werkstoffmechanik, 79108 Freiburg, Germany — ⁴Freiburger Materialforschungszentrum, 79104 Freiburg, Germany

Mass selected clusters from Ag₅₅⁺ to Ag_{923± 9}⁺ were soft landed at 165 K on C₆₀/HOPG and C₆₀/Au(111) and imaged with STM at 77 and 5 K. We observed extremely narrow cluster height distributions. The cluster heights are in agreement with calculated heights for spherical clusters. We studied the thermally activated decay of the deposited clusters. Using C₆₀/HOPG or 2 ML C₆₀/Au(111) the cluster heights are stable for more than 12 h at RT. For 1 ML C₆₀/Au(111) the clusters decay atom by atom, which is revealed by atomistic calculations [1, 2]. For Ag_{309± 3} and Ag_{923± 9}, we used scanning tunnelling spectroscopy at 5 K and measured identical spectral features for individual clusters with the same selected size. The spectra can be classified in different groups showing energetic shifts of the peaks due to different shapes of the STM tip. For this reason, we measured spectra of C₆₀ molecules as reference. Besides, we observed for 2 ML C₆₀/HOPG three different orientations of the C₆₀ molecules in STM images measured at 5 K. In contrast, the first ML C₆₀ molecules/HOPG show only one orientation.

[1] S. Duffe et al., EPJD 45, 3 (2007), [2] S. Duffe et al., submitted