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

The enhancement of N2(B3Πg) and N2+(B2Σu+) states, responsible by the emission bands for the 1+ and 1- systems of N2, in the short-lived afterglow of a flowing N2 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 N2(A3Σu+) and N2(a'1Σu-) states by collisions of N2(X1Σg+,v) molecules in highly vibrational levels with N(4S) 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 N2(X,v) molecules in levels {>}35. During the relaxation process a pumping-up effect for the vibrational quanta at the higher vth levels occurs as a result of near-resonant V-V energy-exchange collisions, that produces a rise in the observed peaks for the N2 electronic states in the flowing afterglow. (author)