Active nitrogen atoms in an atmospheric pressure flowing Ar-N₂microwave discharge

The flowing afterglow of an Ar-N 2 mixed gas plasma gives rise to the recombination of nitrogen atoms according to the reaction N( 4 S)+N( 4 S)+(Ar-N 2 ) KB(V') to N 2 (B 3 pi g ,v')+(Ar-N 2 ) N 2 (B 3 pi g ,v') to N 2 (A 3 Sigma u v")+hv (first positive system). Quantitative optical spectroscopy measurements of the emission spectra of the N 2 (B 3 pi g -A 3 Sigma u ) transition have allowed determination of the total K B and individual K B (v') rates of atomic nitrogen recombination into excited N 2 molecules in the B 3 pi g state with upper vibrational levels v' between 1 and 12. The active nitrogen atoms are produced by dissociation of N 2 molecules in a surface-wave-induced microwave discharge (2450 MHz) sustained in an open-ended dielectric tube. The discharge is operated at atmospheric pressure and the absorbed microwave power is about 200 W for a 5 cm discharge length.