Vinyl torsional potential function of 4-fluorostyrene in the S0 electronic state from electronic absorption and supersonic jet fluorescence spectroscopy

Abstract

Analysis of sequence and cross-sequence bands in the gas phase absorption spectrum together with supersonic jet single vibronic level fluorescence spectra of 4-fluorostyrene, with excitation in the 0 0 0 and 41 0 142 0 1 bands, has given the v 42 = 0–6 term values for the C(1)-C(α) torsional uration is planar but the potential, like that of 4-methylstyrene, is not so flat-bottomed as that of V(θ) cm −1 = 1 2 [(950 ± 60)(1 − cos 2θ) − (229 ± 30)(1 − cos 4θ)] . The torsional barrier height is, like that of 4-methylstyrene, about 10% lower than that in styrene. The large, negative value of V 4 results in a very flat-bottomed potential. The equilibrium configuration is planar but the potential, like that of 4-methylstyrene, is not so flat-bottomed as that of styrene.