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O: Fachverband Oberflächenphysik

O 13: Symposium: Ultrafast Nanooptics II

O 13.5: Vortrag

Montag, 26. März 2007, 16:30–16:45, H38

Electronic properties of silver nanoclusters on oxide supports: Fluorescence microscopy and femtosecond two photon photoemission — Tobias Gleitsmann, Mihai E. Vaida, and •Thorsten M. Bernhardt — Institut für Oberflächenchemie und Katalyse, Universität Ulm, 89069 Ulm, Germany

In the quest for efficiently fluorescent nano-scale materials atomic silver clusters have attracted considerable interest in recent years. Possible applications are in all optical logic devices and in advanced optical data storage media. Unexpectedly, the observed optical properties of silver clusters in the size range with up to about 20 atoms per particle indicate that these clusters cannot yet be considered fully metallic. On the contrary, the observed fluorescence requires the presence of long-lived discrete electronic levels in the cluster-support system. Employing a laser scanning microscope and femtosecond radiation it is possible to write fluorescent silver cluster nano-structures in silver oxide thin films or silver oxide containing biopolymer matrices. The information is long-time stable and can be read out with conventional low intensity light sources. In order to furthermore identify the hitherto unknown electronic structure of atomic metal clusters at surfaces and thus to elucidate the origin of the observed luminescence properties time-resolved two photon photoemission spectroscopy is applied to mass-selected silver metal clusters which have been soft-landed onto a well-defined insulating substrate.