Influence of the environment on the excited state deactivation in functionalized quinque-thienyls

The transient photoinduced transmission of quinquethiophene-S,S-dioxide in solution is reported. Stimulated emission is observed in the viscous solven t, but quenched in polar and nonpolar low viscosity solvents. The lifetime of the photoexcited state changes of more than one order of magnitude depen ding on the solvent properties, pointing out conformational effects. Low-en ergy coherent transient is observed and assigned to real time conformationa l dynamics. (C) 2001 American Institute of Physics.