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MO: Fachverband Molekülphysik
MO 11: Biomolecules
MO 11.1: Talk
Monday, March 19, 2007, 14:00–14:15, 6B
IR/UV-double resonance spectroscopy of electronically excited flavonoids — •Kristina Bartl1, Holger Fricke1, Kirsten Schwing1,2, Andreas Funk1, and Markus Gerhards1,2 — 1H.-Heine Universität Düsseldorf, Institut für Physikalische Chemie I, 40225 Düsseldorf — 2TU Kaiserslautern, Fachbereich Chemie, 67663 Kaiserslautern
Flavonoids are well known for their antioxidative effect. Spectroscopically, flavonoids like 3-hydroxyflavone or 5-hydroxyflavone are of special interest, since a keto-enol-tautomerism takes place after electronic excitation. In order to obtain detailed structural information on the reaction coordinate, combined IR/UV-spectroscopy is applied on electronically excited states in a mass selective molecular beam experiment: In a first step an isomer selective resonant excitation in different electronically excited states is performed and the IR-spectra of these excited states are analyzed by resonant IR-excitation followed by UV-ionisation. By comparison with the isomer selective IR-spectra of the ground state (obtained by another combined IR/UV method) and in combination with ab initio and DFT calculations, structural changes can be identified in detail. Not only the structure sensitive coordinates of the OH and C=O stretching vibrations but also the whole IR spectrum up to the upper fingerprint region can be analyzed by using a newly developed IR laser system. In this presentation investigations of different hydroxyflavones, starting with 3-hydroxyflavone and its clusters with water are presented. Different isomers as well as reaction coordinates are discussed.