Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 88: Metallic Nanostructures II (on Semiconductors)

O 88.2: Vortrag

Freitag, 29. Februar 2008, 09:45–10:00, MA 005

Faceted silver clusters on HOPG and their stability — •Niklas Grönhagen, Farhad Ghaleh, and Heinz Hövel — Technische Universität Dortmund, Experimentelle Physik I, 44221 Dortmund

Silver clusters are interesting objects due to their optical and electronic properties. Close to the Fermi level silver is a nearly free electron metal where the electron delocalization leads to strongly cluster size dependent states [1]. However, the influence of the d-electrons is not negligible, e.g. for the optical properties of the clusters [2]. This interesting electronic structure is combined with a moderate chemical reactivity, which may be the reason why silver is used in many of the experiments for clusters on surfaces.

In the present study we produce faceted silver clusters by depositing silver atoms on HOPG samples, prestructured with nanometer sized pits [3,4]. Subsequently the clusters are investigated with STM. In these experiments we observe different shapes of the cluster facets as well as discrete cluster heights. Furthermore we investigate the clusters in terms of stability in different environments, e.g. air, bad vacuum or after STM-tip interaction.

[1] H. Hövel, B.Grimm, M. Bödecker, K. Fieger, B. Reihl: Surf. Sci. 463, L603 (2000)

[2] U. Kreibig, M. Vollmer, Optical properties of Metal Clusters: Springer Tracts in Materials Science 25 (Springer-Verlag, 1995)

[3] H. Hövel, Appl. Phys. A 72, 295 (2001)

[4] F. Ghaleh, R. Köster, H. Hövel, L. Bruchhaus, S. Bauerdick, J. Thiel, R. Jede: J. Appl. Phys. 101, 044301 (2007)