Hannover 2013 – scientific programme
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MO: Fachverband Molekülphysik
MO 27: Poster 3: Collisions, Electronic Spectroscopy, Energy Transfer, Quantum Chemistry, Molecular Dynamics, Photochemistry, Spectroscopy in He-Droplets
MO 27.26: Poster
Thursday, March 21, 2013, 16:00–18:30, Empore Lichthof
Excited state proton transfer reactions in isolated hydroxychromones investigated by different IR/UV techniques — •Anke Stamm, Martin Weiler, Alexander Brächer, Kirsten Schwing, and Markus Gerhards — TU Kaiserslautern, Fachbereich Chemie Erwin-Schrödinger-Straße 52, 67663 Kaiserslautern
Photochemical reactions as the excited state proton transfer are of high importance in chemical and biological processes. Molecular beam investigations combined with double, triple and quadruple resonance IR/UV spectroscopic techniques are very powerful tools to analyze these photochemically induced reactions. In comparison with (TD)-DFT calculations direct structural information on the electronic ground and electronically excited states of isolated molecules and clusters are obtained. We applied these techniques to isolated and photochemically reactive 3-hydroxychromone (3-HC) including the new IR/UV/IR/UV [1] technique leading to a structure identification for the S0 and electronically excited state and thus to a characterization of the excited state proton transfer. These findings are compared with investigation for formerly analysed proton transfer systems which differ from 3-HC by substitutions: 3-hydroxyflavone and 2-(2-naphthyl)-3-hydroxychromone]. Differences do not only exist in the excited state life times of the molecules and their clusters with water but also in the anharmonicities of OH stretching frequencies of the hydrogen-bonded OH groups leading to significantly different vibrational frequencies.
[1] M. Weiler, K. Bartl, M. Gerhards, J. Chem. Phys.,2012, 136, 114202.