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R. S. RAM, Department of Chemistry, University of Arizona, Tucson, AZ 85721; AND P. F. BERNATH, Department of Chemistry, University of Waterloo, Waterloo, Ont., Canada N2L 3G1.
The emission spectrum of NbN has been reinvestigated in the 15000--35000 cm-1 region using a Fourier transform spectrometer and some new transitions have been observed in the visible region. The bands observed in the 18000--19800 cm-1 region have been assigned as a new 3
- X 3
transition. Three bands with R heads near 19463.8, 19659.0 and 19757.0 cm-1 have been assigned as the 0--0 bands of the 3
2 - X 3
3, 3
1 - X 3
2 and 3
_0^\pm - X 3
1 sub-bands of the new transition. To higher wavenumbers, a 0--0 band with origin near 25409.9 cm-1 has been assigned as a
= 0 transition with X 3
2 as the lower state. A rotational analysis of the 0--0 and 0--1 bands of these sub-bands has been carried out and spectroscopic constants have been extracted. Two additional bands with origins near 25518.7 and 25534.8 cm-1 are
= 0 bands having X 3
1 as the common lower state. Most of excited levels are affected by perturbations.