Study of the electronic ground state of NH2by laser excited fluorescence Fourier transform spectroscopy

A large number of spin-rovibronic levels of the upper electronic state of NH2 have been excited with a single mode rhodamine 6G dye laser. Fluorescence spectra were obtained over a wide spectral range (12 000-3700 cm-1) using a Fourier transform spectrometer. Levels of the bending vibration were observed from ν″2 = 4 up to 10, showing the reordering of the K-structure at the barrier to linearity; their observed energies are in good agreement with the predictions of Jungen, Hallin and Merer [16, 17], Duxbury and Dixon [19] and Perić, Peyerimhoff and Buenker [20]. Numerous vibrational levels involving nv 1 and 2v 3 were also detected and approximate anharmonic parameters have been deduced. Local perturbations are observed and discussed; the interpretations proposed by Jungen et al. [18] for some of these in the à 2 A 1 state are experimentally confirmed.