Knowledge Bank

The $A~1B2-X~1A1$ two-photon fluorescence excitation spectrum of benzotrifluoride in the gas phase has been recorded and analysed in the total energy range of $37800cm-1$ to $40300cm-1$ using both linearly and circularly polarized light from a Nd-YAG pumped dye laser. The band system comprised of two groups, one group being unaffected and the other diminishing in intensity under circular polarization of the laser beam. The two-photon tensor patterns can be used to understand these behaviour. The intensity ordering of the bands in the two-photon spectrum is (Wilson numbering convention) while in one-photon spectrum the origin band is the strongest. The spectral features of benzotrifluoride are compared with fluorobenzene and toluene.