Stuttgart 2012 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 21: Poster 3: Cluster, Collisions, Energy Transfer, Photochemistry, Spectroscopy in He-Droplets

MO 21.20: Poster

Donnerstag, 15. März 2012, 16:30–19:00, Poster.IV

ESIPT in isolated hydroxychromones: Analysis by combined IR/UV spectroscopy — Martin Weiler, Alexander Brächer, •Anke Stamm, Kristina Bartl, and Markus Gerhards — TU Kaiserslautern,Physikal.&Theoret. Chemie,67663 Kaiserslautern

Photochemical reactions are of interest due to their importance in chemical and biological processes. Combined double, triple and partly quadruple resonance IR/UV spectroscopic techniques in molecular beam experiments in combination with (TD-) DFT calculations are very powerful tools to analyze photochemically induced reaction coordinates yielding direct structural information on the electronic ground and electronically excited states. We applied different combined mass- and isomerselective IR/UV and IR/IR techniques on the isolated and photochemically reactive 3-hydroxychromone (3-HC). By comparing the IR spectra of the electronic ground and an electronically excited state (S1) with (TD-)DFT calculations a proton transfer reaction after electronic excitation was verified and the resulting geometry can be identified. These findings are compared with observations for 3-hydroxyflavone and 2-(2-naphthyl)-3-hydroxychromone which differ from 3-hydroxychromone by substitutions. Especially the different life times of the molecules and their clusters with water in the first electronically excited state require the use of the large variety of combined IR/UV methods in order to get correct assignments on the different species and their reaction channels. These aspects will be discussed in detail.