Spectral Study of a Visible, Short-Duration Afterglow in Nitrogen

Abstract

In the discharge products of rapidly flowing, pure nitrogen at pressures between 4 and 15 mm Hg, an afterglow differing from the usual Lewis-Rayleigh afterglow has been found to occur approximately 5 milliseconds after the discharge. This pink-colored afterglow persists for about 2 milliseconds and is both preceded and followed by the usual yellow glow of active nitrogen. In the visible and near ultraviolet, this short-duration glow is characterized by strong emission of N2+ (B 2Σu+−X 2Σg+) and N2 1st positive (B 3Πg−A 3Σu+) bands and weak emission of N2 2nd positive (C 3IIu—B 3IIg) bands. The vibrational intensity distributions of the bands are similar to that of the discharge, including strong emission from vibrational levels above the predissociation limit of the B 3IIg state. The existence of this afterglow shows the presence of highly energetic species other than nitrogen atoms after the discharge.