Studies of molecular nitrogen bands from airborne auroral spectroscopy

Absolute auroral emission rates of several bands of the 1 PG (first positive), 2 PG, and Vegard-Kaplan systems of N2 and of the 1 NG (first negative) system of N2(+) were obtained from simultaneous spectral scans of two Ebert spectrophotometers mounted on board the NASA CV 990 aircraft. Analysis of these bands emitted during a 2-min auroral event leads to some conclusions regarding the excitation mechanisms of the C(3)Pi, B(3)Pi, and A(3)Sigma levels: the v' = 0 to v' = 3 levels of the C(3)Pi electronic state are populated by electron impact; the cross sections predict absolute emission rates that are in good agreement with the observations. Cross sections for excitation of the v' = 4 to v' = 8 levels, derived from laboratory measurement of the optical excitation functions, predict well the 1 PG bands observed in the auroral event.