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MO: Fachverband Molekülphysik

MO 5: Photochemie I

MO 5.2: Talk

Tuesday, March 11, 2008, 09:00–09:15, 3F

Solvent effects in the excited state reaction dynamics of molecular switches — •Florian J. Lederer¹, Stephan Malkmus¹, Thomas Brust¹, Simone Draxler¹, Jessica A. DiGirolamo², Watson J. Lees², Wolfgang Zinth¹, and Markus Braun¹ — ¹Ludwig-Maximilians-Universität München, Lehrstuhl für BioMolekulare Optik, — ²Department of Chemistry and Biochemistry, Florida International University

Indolylfulgides exhibit a photochemical ring-opening/ring-closure reaction on the picosecond timescale. The different isomers are thermally stable and have strongly separated absorption bands, which facilitate their use as optical memory elements.

We performed femtosecond-spectroscopy to study the ring-opening reaction of a fluorinated indolylfulgid in different solvents. The temperature-dependent time constants and quantum yields of the reaction are explained by an activated behaviour: the ring-opening evolves over a barrier.

This barrier is influenced by the surroundings of the molecule. Onsager and Kirkwood gave an approximation for the energy displacement of a single molecule due to the change of the dielectric properties of the solvent. In combination with a Marcus-like model, this approximation can be used to describe the influence of the solvent on the photochemical reaction.