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 2∑ u+2∑g+) and N2 1st positive (B 3IIg-A 3∑U+) 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.