Role of long-lived N₂(X¹Σg⁺,v) molecules and N₂(A³Σu⁺) and N₂(a'¹Σu⁻) states in the light emissions of an N₂afterglow

The enhancement of N 2 (B 3 Π g ) and N 2 + (B 2 Σ u + ) states, responsible by the emission bands for the 1 + and 1 - systems of N 2 , in the short-lived afterglow of a flowing N 2 microwave discharge at ω/(2π) = 433 MHz is investigated by modelling. It is shown that pronounced maxima for both emissions are obtained downstream from the discharge by assuming the formation of N 2 (A 3 Σ u + ) and N 2 (a' 1 Σ u - ) states by collisions of N 2 (X 1 Σ g + , v ) molecules in highly vibrational levels with N( 4 S) atoms. Other channels that can also produce the emissions are investigated as well, but the common factor in all of them is the role played by the vibrationally excited N 2 (X, v ) molecules in levels {>}35. During the relaxation process a pumping-up effect for the vibrational quanta at the higher v th levels occurs as a result of near-resonant V-V energy-exchange collisions, that produces a rise in the observed peaks for the N 2 electronic states in the flowing afterglow.