The multiphoton ionization spectrum of benzene

Abstract

A resonance seen in the multiphoton ionization spectrum of benzene at 391.4 nm is identified as a two-photon resonance with a bound state at 51 085 cm−1. This state has probable symmetry 1E1g or 1E2g as indicated by an active e2g vibration. No other allowed two-photon transitions are seen below this energy. Three-photon resonances with the Rydberg states of benzene are seen and compared to the one-photon absorption spectrum. The great similarity indicates a strong 1A1g component in the two-photon virtual state. Two-photon resonances with the 1B2u state agree with two-photon fluorescence excitation spectra but show no diminution above the energy where fluorescence is quenched.