SPECTROSCOPY AND DYNAMICS OF JET-COOLED 4-AMINOBENZONITRILE (4-ABN)

Laser-induced fluorescence (LIF) excitation and emission spectra and f luorescence lifetimes of jet-cooled 4-aminobenzonitrile (4-ABN) are re ported. The dispersed fluorescence following excitation of transitions in the medium and high excess energy region in the S1 manifold are ex amined. Strong Fermi resonances between the I-0(2) (0(0)0 + 807 cm-1) and 1(0)1 (0(0)0 + 815 cm-1) bands are observed. The inversion mode do minates in most dispersed fluorescence spectra, confirming the importa nce of the fluxional amino group in 4-ABN. Broad and unstructured emis sion in this region is observed for 4-ABN under jet conditions, which may be associated with intramolecular vibrational redistribution (IVR) . The relatively low onset of IVR in 4-ABN is attributed mainly to the activity of the fluxional amino group.