Ultrafast Dynamics of Benzene on the <i>S</i>₂ State Investigated by Femtosecond Time-Resolved Photoelectron Spectroscopy

Abstract

The ultrafast dynamics of benzene on the S 2 state have been investigated by femtosecond time-resolved mass spectroscopy coupled with photoelectron imaging. The benzene molecule was excited to the S 2 state by two 400 nm photons, and subsequently probed by one 267 nm photon. The timedependent ion yield of the parent ion consists of two components with different lifetimes. The first component at (90 ± 1) fs is because of internal conversion from the S 2 state to the S 1 /S 0 state. The second one, i.e., (5.0 ± 0.2) ps, is due to decay of the S 1 state. The observed lifetime of the second component is shorter than previous results, indicating the existence of an additional decay process. With photoelectron spectra extracted from the time-resolved photoelectron imaging, this newly found deactivated process is assigned to intersystem crossing from the vibrational excited S 1 state to the hot triplet state T 3 .