The intensity distribution in the second positive band system of nitrogen in a laboratory light source and in the aurorae

Abstract

The intensity distribution in the second positive band system of N 2, emitted from an ordinary discharge lamp is measured, and the relative transition probabilities are derived. Vegard's intensity measurements of these bands in high latitude aurorae are discussed, the most likely relative population of the upper vibrational levels (N 2C 3II u ) being found to be g(0) = 1.0, g( I) = 0.6 and g(2) = 0.35. It can be shown that the excitation mechanisms N 2( 1Σ g +) + e → N 2( C 3 II u ) + e or N 2 + ( X 2 Σ g +) + e → N 2( C 3 II u ) + hv cannot alone be responsible for this population.