On the difficulty of N(4S) atom recombination to explain the appearance of the pink afterglow in a N2flowing discharge

The possibility that the pink afterglow (PA) of a flowing nitrogen discharge occurs as a result of recombination of N( 4 S) atoms is evaluated and discussed, based on a detailed kinetic model for a microwave discharge and post-discharge. The present simulation shows that the states responsible for the emission of the PA cannot be created via an indirect mechanism initiated with atomic recombination. Alternatively, it is indicated that the PA may have its origin in non-resonant vibration–vibration energy-exchange processes between molecules, which lead to an overpopulation of high levels of the vibrational manifold.