Observed Intensity Ratios of the N₂ 1PG Bands in Aurora

Abstract

In evaluating the relative importance of direct electron impact vs. cascading in the excitation of the N₂ first positive (1PG) system it is necessary to measure accurately the relative intensities of bands from as many different v′ levels as possible to establish the relative populations. Gattinger and Vallance Jones (1974) have obtained measurements of the vibrational development of the system in medium intensity aurora, and have compared their results with various theoretical distributions. Vallance Jones and Gattinger (1972) made similar but less comprehensive measurements on bright aurora and arrived at ratios for I(1,0):I(2,1):I(3,2) which were quite different from those determined in the later paper (Table I).