Knowledge Bank

Although the $B2\sum \mu +-X2\sum g+$ system of $N2+$ is well known, there have been only a few previous studies of the Meinel system (A-X).$\mathrm{<mrow\; data-mjx-texclass="ORD">1-4</mrow>}$ Infrared emission spectra of the $N2+$ molecular ion have been recorded from 4000--11000$cm-1$ at 0.013$cm-1$ resolution using the Fourier transform interferometer of the Laboratoire d’Infrarouge. Orsey, France. The best signal-to-noise ratios were obtained using a hollow cathode source with flowing nitrogen although a positive column discharge was also used. Nine bands of the $N2+$ Meinel system were observed (0-0, 0-1, 0-2, 1-0, 1-1, 1-2, 1-3, 2-3), several for the first time and the others at higher resolution than recorded previously. Most of these bands have been subjected to a detailed spectral analysis to provide new, more precise molecular parameters for the $A2\Pi 4$ and $X2\sum 5+$ states, especially the spin-rotation constant of the ground state which is difficult to determine from the B-X system. Equilibrium parameters are also determined in this analysis.