Two-photon excitation spectroscopy of benzene and toluene in nonpolar liquids

Abstract

The two-photon excitation spectra of benzene and toluene in dilute solutions of tetramethylsilane, n-pentane, perfluoro- n-hexane, perfluoromethylcyclohexane, and perfluorodimethylcyclobutane have been measured over the laser excitation wavelength region from 360 to 560 nm, corresponding to a two-photon energy range from 55 500 to 35 700 cm −1. Vibrational analyses of the 1 B 2 u state of benzene from 36 570 to 47 280 cm −1 and of the 1 B 2 state of toluene from 36 100 to 44 700 cm −1 have been conducted and polarization measurements of the 1 B 2 u state, using both linearly and circularly polarized light, are presented and discussed. The 0-0 levels of the 1B 2u ← 1A 1g transitions of benzene and the 1B 2 ← 1A 1 transitions of toluene were observed at 38 050 ± 10 cm −1 and 37 411 ± 10 cm −1 in perfluoro- n-hexane and at 37 853 ± 20 cm −1 and 37 210 ± 20 cm −1 in n-pentane, respectively.