Photoisomerization of stilbene in low viscosity solvents: Comparison of isolated and solvated molecules

Abstract

The photoisomerization of stilbene has been studied in low viscosity liquid alkanes and in the gas phase. The barrier crossing process shows no evidence of a low-friction or energy controlled region even at the lowest liquid viscosities studied. We present evidence that the barrier crossing may be in the energy controlled region in the thermal vapor. We discuss the influence of intramolecular vibrational energy transfer on the observed dynamics and note that entropy effects should be considered in comparing experimental data with theoretical models.