Dispersed fluorescence from the 460-nm band system of NiCl2: Observation of a new, low-lying electronic state

The dispersed fluorescence spectrum of lines in the 460 nm band system of NiCl2(nickel dichloride) is presented. The fluorescence was pumped on single rotational transitions of two spin components in a vibrational band observed previously in the laser excitation spectrum. Fluorescent transitions to levels of theX̃3Σ−g(ground) state are assigned and discussed. The spectra also show clear evidence for a previously unidentified low-lying electronic state, assumed to be theÃstate, which lies about 2000 cm−1above the ground state. This is likely to be of3Πgcharacter and is discussed on that basis. The wavenumber of the symmetric stretching vibration of NiCl2in theÃstate is determined to be 367 cm−1, slightly larger than theX̃state value (360 cm−1).