Active Nitrogen and the Auroral Spectrum

Abstract

A new afterglow of nitrogen has been photographed in the visible and the near ultraviolet. Its spectrum consists of the first-negative bands of ${\mathrm{N}}_2^{+}$, first-positive bands of ${\mathrm{N}}_2$ which originate on the vibrational levels $v^{\prime }=15, 16, 17, 18 \mathrm{and} 19$, and the second-positive group of nitrogen. The ordinary afterglow of nitrogen is also present but very weak. The spectrum of the afterglow is a very faithful reproduction of that part of the auroral spectrum which is due to nitrogen. The spectrum of the exciting discharge resembles that of the afterglow very closely. These facts are used as a basis for the hypothesis that the auroral spectrum is the superposition of a discharge spectrum and an afterglow spectrum. Attention is called to proposed extensions of the experiments.