Ultrafast dynamics through conical intersections and intramolecular vibrational energy redistribution in styrene

摘要

We report a femtosecond time-resolved photoelectron spectroscopy (TRPES) investigation of internal conversion in the first two excited singlet electronic states of styrene. We find that radiationless decay through an S1/S0 conical intersection occurs on a timescale of ~4 ps following direct excitation to S1 with 0.6 eV excess energy, but that the same process is significantly slower (~20 ps) if it follows internal conversion from S2 to S1 after excitation to S2 with 0.3 eV excess energy (0.9 eV excess energy in S1).