Conformation and laser-induced fluorescence spectroscopy of phenetole in supersonic jet

Laser-induced fluorescence excitation and dispersed fluorescence spectra of phenetole have been measured in a cold supersonic jet expansion. The spectral features reveal the presence of only one conformer of the molecule in the environment of the jet, and the finding is consistent with the quantum chemistry predicted relative stability and conformational isomerization barriers of different isomers. The vibronic bands in the dispersed fluorescence spectra have been assigned fully with the aid of the normal mode frequencies predicted by density functional theoretical calculation. The geometry in the S1 state has been optimized and the excited state vibrational frequencies have been calculated by CASSCF method. The theoretical results have been used to interpret the measured spectra.