Hannover 2010 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 4: Spectroscopy in He droplets

MO 4.3: Vortrag

Montag, 8. März 2010, 17:15–17:30, F 142

Electronic Spectroscopy of Anthracenes in superfluid helium droplets I: finestructure — •Dominik Pentlehner and Alkwin Slenczka — Universität Regensburg, Institut für Physikalische und Theoretische Chemie, 93053 Regensburg, Germany

In the last decade, Helium nanodroplets became a popular matrix for the spectroscopy of single atoms, molecules and clusters.[1] Compared to the corresponding spectra in a supersonic beam, electronic spectra of molecules exhibit a solvens shift, phonon wings (PWs) and in various cases a splitting, missing or broadening of the zero phonon line (ZPL) of vibronic transitions.

We have investigated the electronic spectra of anthracene and some substituted anthracenes in helium droplets. A splitting of the ZPLs could only be found for the unsubstituted anthracene. The transitions of all other compounds are dominated by a single ZPL accompanied by a PW exhibiting a finestructure which is similar for different anthracene compounds. PWs represent the excitation spectrum of the helium environment. The occurrence of PWs in electronic spectra of molecules in helium droplets will be discussed on the basis of an empirical model in analogy to the Franck Condon principle for molecular vibrations. The finestructure of the anthracene molecules will be compared to those of Phthalocyanine and Fluorazene representing different cases of the model.

[1] Stienkemeier, F. and Lehmann, K. K.; J. Phys. B: At. Mol. Opt. Phys. 39 (2006) R127-R166