N2+ Meinel Auroral Spectra in the 1.5 μ Region

Abstract

Auroral spectra of the N2+ Meinel bands in the 1.45 to 1.55 μ. region were obtained from very bright auroral displays at Fort Churchill in January 1972. The intensity of the [OI] 5577 Å auroral emission in the field of view of the spectrometer was monitored with a photometer to enable corrections for auroral intensity fluctuations during the spectral scans and reference to the standard auroral brightness to be made. Since an aurora as bright as about IBC III was required to produce emission features comparable with those from the hydroxyl system in the night airglow, very few spectra with prominent auroral features were obtained as an IBC III aurora seldom occurred. The results suggest that direct electron excitation of N2 is the major mechanism for populating the N2+ (A2Π)ν′ = 0 and 1 levels.