High-resolution Fourier transform studies of molecular ion emission: ground state degeneracy splitting in the 1,2,3-trifluorobenzene radical cation

High-resolution fluorescence emission spectra of the supersonically cooled ions are measured on a Fourier transform spectrometer. The asymmetric fluorine substitution splits the doubly degenerate benzene cation ground state into an X~ and low-lying A level. Transitions from the B~ state to each of the X~ and A states can be easily identified based on the analysis of the rotational contours. The results are compared with a previous matrix study, and it is shown that the ionic spectra are insignificantly perturbed in solid neon