A new electronic state of aniline observed in transient IR absorption spectrum from S(sub 1) in a supersonic jet

An ultraviolet (UV)-infrared (IR) double resonance spectroscopy with related fluorescence detection is applied to the observation to the IR spectrum of aniline in the first electronically excited (S(sub 1)) state. On examining the IR spectra for several deuterium substituted species, it is found that NH2 stretching vibrations of the S(sub 1) state are located at 3000 cm(super -1), representing extremely large frequency decrease upon electronic excitation.