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 S-0 state. High-level MO calculations suggest that frequencies of mode 15 and delta(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. (C) 2008 Elsevier B.V. All rights reserved.