@article{StromeckFaderlPentlehnerKensyetal.2011, author = {Stromeck-Faderl, A. and Pentlehner, Dominik and Kensy, U. and Dick, B.}, title = {High-resolution electronic spectroscopy of the BODIPY chromophore in supersonic beam and superfluid helium droplets}, series = {CHEM-PHYS-CHEM, Special Issue: Laser Chemistry and Spectroscopy}, journal = {CHEM-PHYS-CHEM, Special Issue: Laser Chemistry and Spectroscopy}, number = {12}, year = {2011}, abstract = {We present the fluorescence excitation and dispersed emission spectra of the parent compound of the boron dipyrromethene (BODIPY) dye class measured in a supersonic beam and isolated in superfluid helium nanodroplets. The gas-phase spectrum of the isolated molecules displays many low-frequency transitions that are assigned to a symmetry-breaking mode with a strongly nonharmonic potential, presumably the out-of-plane wagging mode of the BF2 group. The data are in good agreement with transition energies and Franck-Condon factors calculated for a double minimum potential in the upper electronic state. The corresponding transitions do not appear in the helium droplet. This is explained with the quasi-rigid first layer of helium atoms attached to the dopant molecule by van der Waals forces. The spectral characteristics are those of a cyanine dye rather than that of an aromatic chromophore.}, language = {en} }