title: Ultrafast excited-state dynamics of phenyleneethynylene oligomers in solution.
abstract: The excited-state dynamics of oligomeric phenyleneethynylenes (OPEs) of various length and substitution has been investigated by femtosecond time-resolved spectroscopy. The fluorescence lifetime of the OPEs decreases with the number of phenyleneethynylene units up to about 9. This effect is due to an increase of the oscillator strength for the S(1)-S(0) transition. Dynamic features occurring within a few tens of picoseconds and ascribed to structural relaxation directly after population of the S(1) state can be observed in non-viscous solvents. The effect of torsional disorder on the fluorescence intensity is shown to depend strongly on the nature of the substituent on the phenyl groups. All these effects are qualitatively discussed with a simple exciton model.
authors.affiliation: Department of Physical Chemistry of the University of Geneva, 30 quai Ernest-Ansermet, CH-1211, Geneva 4, Switzerland.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Duvanel
authors.forename: Jakob
authors.initials: J
authors.lastname: Grilj
authors.forename: Anne
authors.initials: A
authors.lastname: Schuwey
authors.forename: Albert
authors.initials: A
authors.lastname: Gossauer
authors.forename: Eric
authors.initials: E
authors.lastname: Vauthey