Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 18: Poster Session I - MA 141/144 (Atomic Wires; Size-Selected Clusters; Nanostructures; Metal Substrates: Clean Surfaces+Adsorption of Organic / Bio Molecules+Solid-Liquid Interfaces+Adsorption of O and/or H; Surface or Interface Magnetism; Oxides and Insulators: Clean Surfaces)
O 18.15: Poster
Montag, 25. Februar 2008, 18:30–19:30, Poster F
Size-dependent Photoabsorption and Photoemission of Supported Silver Clusters and Silver Cluster-Biomolecule Hybrid Systems — •Roland Mitric, Christian Bürgel, Jens Petersen, Alexander Kulesza, and Vlasta Bonacic-Koutecky — Humboldt-Universität zu Berlin, Institut für Chemie, Brook-Taylor-Str. 2, D-12489 Berlin, Germany
Silver clusters interacting with different environments such as surfaces or biomolecules exhibt fascinating absorption and emissive properties which can be exploited for biosensing and optoelectronic applications. We address theoretically size dependent structural and optical properties of silver clusters Agn (n=2,4,6,8) suppported on MgO surface as well as optical properties of silver-cluster tryptophan hybrid systems Trp-Agn+ (n=1-9). Our results on supported silver clusters provide insight into the mechanism responsible for absorption and emission patterns arising from interaction between the excitation within the cluster and the environment. We demonstrate that small clusters such as Ag4 are good candidates for fluorescence centers in the visible regime. Furthermore, in the Trp-Agn+ hybrid system we identified different types of charge transfer between the silver and biomolecule subunits. Remarkably, we observe a strong reduction of the photofragmentation yield in Trp-Ag9+ in comparison with free Ag9+ which may be attributed to energy dissipation by fluorescence. Thus, the unique optical properties of supported silver nanoclsuters combined with the specific bio-recognition of biomolecules will provide fundamentals for the future development of fluorescent nanocluster-based biochips.