Determination of non-Boltzmann vibrational level populations of excited nitrogen using the Penning ionisation technique

Vibrational level population distributions of electrical-discharge-excited nitrogen were measured up to nu =7 by means of a Penning ionisation reaction involving He(2 3 S) metastables. Vibrational level populations of N 2 (X, nu ) were obtained from the N 2 + (B, nu 1 ) level concentrations and the inverted matrix of the Franck-Condon factors. A vibrational temperature range of 2000-8000K was covered with all measured vibrational distributions exhibiting non-Boltzmann, near-Treanor quasi-steady-state behaviour.