Hamburg 2009 – scientific programme
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MO: Fachverband Molekülphysik
MO 23: Molekülphysik Poster 2
MO 23.3: Poster
Thursday, March 5, 2009, 16:30–19:00, VMP 8 Foyer
High resolution electronic spectroscopy of porphyrine derivatives in superfluid helium nanodroplets — •Ricarda Riechers and Alkwin Slenczka — University of Regensburg, Germany
A combination of laser induced fluorescence excitation and dispersed emission spectra delivers insight into intramolecular dynamics of molecules inside superfluid helium nanodroplets. Characteristic features in the electronic spectra such as fine structure in vibronic transitions as well as the frequency shift of the 000 transition in excitation and emission are indicative for dynamic processes either within the embedded molecule or within its closer environment. This experimental approach was applied to several porphyrine derivatives as well as to molecular aggregates consisting of one porphyrine molecule and either an argon atom or a water molecule. In the case of chloroaluminiumphthalocyanine (AlClPc) the van der Waals complexes with argon showed a rich spectrum of sharp transitions. By help of the dispersed emission spectra the signals of isomeric complexes could be identified. Particularly, the emission spectra of some AlClPc-Ar1-complexes showed a rich fine structure of the emission origin which repeats in the vibrational transitions. This can be ascribed to a relaxation of the configuration of the solvated complex upon electronic excitation. Regarding AlClPc-(H2O)n in helium droplets, one can study the complexation of two polar molecules under low temperature conditions. By using Stark-field induced optical anisotropy measurements structural information about the possible complex isomers becomes accessible.