Knowledge Bank

The emission spectrum of NbN has been reinvestigated in the 15000--35000 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ 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$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ region have been assigned as a new $3\Pi -X3\Delta$ transition. Three bands with R heads near 19463.8, 19659.0 and 19757.0 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ have been assigned as the 0--0 bands of the $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Pi 2-X3\Delta 3$, $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Pi 1-X3\Delta 2$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Pi 0\pm -X3\Delta 1$ sub-bands of the new transition. To higher wavenumbers, a 0--0 band with origin near 25409.9 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ has been assigned as a $\Delta \Omega$ = 0 transition with $X3\Delta 2$ 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$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ are $\Delta \Omega$ = 0 bands having $X3\Delta 1$ as the common lower state. Most of excited levels are affected by perturbations.