Nitrogen Molecular Spectra in the Vacuum Ultraviolet

Nitrogen molecular spectra in the region from 900A to 2300A have been photographed with a 10-foot vacuum spectrograph giving a dispersion of 5.5A/mm. Partial rotational quantum analyses have been made for several bands of the a¹Πᵤ→¹Σg⁺ system yielding the constants B₀^'=1.632±0.002, B₀^''=1.998±0.002, α^'=0.021, α^''=0.018. Many new bands in a nitrogen band system with an origin at 1847A discovered by Hopfield in a condensed discharge in a helium-nitrogen mixture are reported. This system is due to N₂⁺, having the same lower state as that of the first negative system. The r\^ole of the helium is discussed. Birge and Hopfield's b^' progression is found to consist of Q branches only with B^'=1.147. Several new N₂ ground state progressions among the bands in the 900A-1300A interval are presented.