Molecular structure of jet-cooled thioanisole studied by laser-induced fluorescence spectroscopy and ab initio calculations: Planar and/or perpendicular conformation?

Laser-induced fluorescence (LIF) excitation and dispersed fluorescence (DF) spectra of jet-cooled thioanisole were measured for the first time. The DF spectrum was obtained by pumping the origin band to investigate the molecular structure in the S0 state. High-level MO calculations suggest that frequencies of mode 15 and δ(CSC), the deformation of the thiomethyl group, were very sensitive to orientation of the thiomethyl group. Analysis of the vibrational mode of the DF spectrum demonstrates that the most stable structure is planar. Analysis of low-frequency vibrational modes is found to be important to determine the flappy structures.