Femtosecond time-resolved photoionization and photoelectron spectroscopy studies of ultrafast internal conversion in 1,3,5-hexatriene

Ultrafast photodynamics in a 1,3,5-hexatriene are studied using femtosecond time-resolved photoionization and photoelectron spectroscopy. The trans and cis isomers have distinctly different dynamics following excitation at the S-2 Origin near 250 nm. An intermediate, presumably the S-1 state, is observed for both trans and cis isomers with lifetimes of 270 fs and 730 fs, respectively. Time-delayed photoelectron spectra of cis-hexatriene determine a 300 fs time scale for vibrational energy redistribution within the intermediate S-1 state. (C) 1996 American Institute of Physics.