Quantitative spectroscopy of the aurora. V. The spectrum of strong aurora between 10 000 and 16 000 Å

Abstract

The auroral spectrum between 10 000 and 16 000 Å has been examined with a resolution of 12 Å by means of a Michelson interferometer. As a result of the high accuracy of the spectral data obtained by this technique, it has been possible to derive a pure auroral spectrum by subtracting the nightglow spectrum obtained under identical conditions in the absence of aurora. The spectrum was then matched by a synthetic spectrum composing N₂ and N₂⁺ bands and atomic lines so as to measure the intensities of the components of the auroral spectrum. The first positive N₂ band intensities agree well with the values predicted from analysis of the spectrum below 11 000 Å. On the other hand the intensities of the Δν = −1 bands of the N₂⁺ Meinel system make possible an improved electronic transition moment function, [Formula: see text], for the system. The vibrational population rates derived from the spectrum by means of the new function are closer than before to values predicted by the Franck–Condon principle.