The role of intersystem collisional transfer of excitation in the determination of N2 vibronic level populations. Application to B′ 3Σ−u–B 3πg band intensity measurements

Abstract

This work constitutes a two-part study of molecular nitrogen in laboratory electric discharges. In the first part, an investigation is undertaken of the phenomenon of the intersystem collisional transfer (ICT) of excitation (recently advanced as the process which gives rise to the reddening of type B aurora) in which ICT is established as a dominant mechanism controlling the distribution of vibronic level populations under discharge conditions. In particular, it is determined that there occur many pairs of vibronic levels in adjacent electronic states in which the pair partners attain essentially identical populations through the agency of collisional coupling. In the second part, the knowledge of completely shared populations is combined with the results of a series of measurements of emission band intensities in N2 to obtain transition probabilities and transition moments for the infrared afterglow system B′ 3Σ−u –B 3πg. A tabulation of transition probabilities and vibronic level lifetimes for this system is presented.