Vacuum ultraviolet emission by active nitrogen. I. The formation and removal of N 2 (a 1 Π g )

Abstract

The emission of the Lyman-Birge-Hopfield bands of N 2 (a 1 Π g ) - X 1 ∑ g + ), v ' ≤ 6 in active nitrogen is shown to originate from the recombination of ground state nitrogen atoms. Two parallel processes occur: ( а ) A two-body inverse predissociation populates rotational levels J > 13 of N 2 (a 1 Π g ), v ' = 6, from which there is rapid rotational and vibrational relaxation; this gives an emission intensity proportional to [N] 2 . ( b ) The reaction N( 4 S) + N 2 (B 3 Π g ) = N 2 (a 1 Π g ) + N( 4 S) (5) populates mainly lower levels of the a a 1 Π g state giving emission proportional to [N] 3 which is enhanced by argon carriers. Some measurements on N 2 (a' 1 ∑ u - ), v ' = 0 are also reported.