FOURIER TRANSFORM EMISSION SPECTROSCOPY OF NEW VISIBLE SYSTEMS OF NbN

Author Institution: Department of Chemistry, University of Arizona, Tucson, AZ 85721; Department of Chemistry, University of Waterloo, Waterloo, Ont., Canada N2L 3G1The 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 $\;^{3}\Pi - X\;^{3}\Delta$ 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 $^{3}\Pi_{2} - X\;^{3}\Delta_{3}$, $^{3}\Pi_{1} - X\;^{3}\Delta_{2}$ and $^{3}\Pi_{0^\pm} - X\;^{3}\Delta_{1}$ 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 $\Delta\Omega$ = 0 transition with $X\;^{3}\Delta_{2}$ 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 $\Delta\Omega$ = 0 bands having $X\;^{3}\Delta_{1}$ as the common lower state. Most of excited levels are affected by perturbations