The <i>S</i>2 ← <i>S</i> laser photoexcitation spectrum and excited state dynamics of jet-cooled acetophenone

Abstract

The S2 ← S0 photoexcitation spectrum of jet-cooled acetophenone is presented. The observed homogeneously broadened linewidths indicate S2 lifetimes ≤0.26 ps while the measured emission lifetimes range from 540±30 ns for S2 000 excitation to 130±50 ns for S2 1210 excitation. The dynamics revealed by the spectrum are discussed in terms of the known photochemical and photophysical rates of the excited states of acetophenone. Arguments are presented which identify the emitting state as a known triplet state of acetophenone.