title: High-resolution electronic spectroscopy of the BODIPY chromophore in supersonic beam and superfluid helium droplets.
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 BF(2) 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.
authors: Institut für Physikalische and Theoretische Chemie, Universität Regensburg, 93053 Regensburg, Germany.
authors: Anja
authors: A
authors: Stromeck-Faderl
authors: Dominik
authors: D
authors: Pentlehner
authors: Uwe
authors: U
authors: Kensy
authors: Bernhard
authors: B
authors: Dick