Journal of Chemical Physics, Vol.111, No.9, 3898-3910, 1999
Vibronic spectroscopy of jet-cooled indazole: S-1 <-> S-0 spectra and mode assignments
The S-0<----> S-1 electronic transition of 1H-indazole has been investigated by laser-induced fluorescence (LIF) excitation and dispersed fluorescence (DF) spectroscopies in a supersonic free jet expansion. Ground and excited state vibrational modes were assigned based on the observed band frequencies and intensities, ab-initio frequency calculations, and available infrared absorption data. Unexpected "symmetry forbidden" transitions were observed in the DF, which, according to our assignments, would originate from the 27(1) excited state in-plane fundamental to several ground state out-of-plane fundamentals. Accepting the assignments, this observation would indicate a vibronic coupling between the S-1 (or S-0) state (A') and an excited n pi(*)-type electronic state of A " symmetry.