Regensburg 2010 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 9: Focus Session: Structural dynamics in photoexcited molecules

DF 9.3: Topical Talk

Wednesday, March 24, 2010, 11:00–11:20, H11

Photoinduced isomerization of molecular switches at metal surfaces — •Petra Tegeder — Freie Universität Berlin, Institut für Experimentalphysik, Arnimallee 14, 14195 Berlin

Molecular switches represent a fascinating class of functional molecules, whose properties can be reversibly changed between different molecular states by excitation with light or other external stimuli. Using surface science concepts like self assembly to align such molecules in a well defined geometry at solid surfaces, new functional properties may arise, which are relevant for different fields like, e.g., molecular electronics, sensing or biocompatible interfaces. For a microscopic understanding of molecular switching at surfaces, it is essential to obtain detailed knowledge on the underlying elementary processes, for instance the excitation mechanism in photoinduced switching.

I will present a case study of a specifically designed azobenzene derivative on a metal surface, namely tetra-tert-butyl-azobenzene (TBA) adsorbed on Au(111), which is so far one of the best studied system for which reversible conformational changes have been demonstrated. The trans/cis-isomerization of TBA is accompanied by reversible changes in the geometrical and electronic structure of the molecules, allowing to gain mechanistic and quantitative insight into the switching process. Our results demonstrate the feasibility of molecular switching at metal surfaces, but also indicate that the switching properties of the surface-bound species are strongly modified by the interaction with a metal substrate.