Role of long-lived N2(X1Σ+g, υ) molecules and N2(A3Σ+u) and N2(a'1Σ-u) states in the light emissions of an N2 afterglow

The enhancement of N-2(B (3) Pi (g)) and N-2(+)(B (2) Sigma (+)(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 omega/(2 pi) = 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) Sigma (+)(u)) and N-2(a' (1) Sigma (-)(u)) states by collisions of N-2 (X (1) Sigma (+)(g), upsilon) molecules in highly vibrational levels with N(S-4) 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,upsilon) 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 N-2 electronic states in the flowing afterglow.