Excitation of N2(B 3Πg) in the nitrogen short-lived afterglow

The excitation of the N-2(B(3)Pi(g)) state in microwave discharges ignited in flowing nitrogen and in their short-lived afterglow is investigated. Simultaneous measurements in the post-discharge on this species and the N-2(+)(B(2)Sigma(mu)(+)) ion through emissions, and also on the electronic ground state of NZ by spontaneous Raman scattering, provide information of their vibrational distribution function. A spatial study has been carried out, showing a quite slow evolution of the vibrational populations along the short-lived afterglow, and in particular the first proof of a steady vibrational distribution of N-2(X(1)Sigma(g)(+)) from the beginning to the bulk of this ionized region. The N-2(B(3)Pi(g) vibrational distribution is analysed by a steady-state kinetic model taking into account all the B state excitation processes, i.e. electron collisions and reactions between molecular excited states, and quenching. The reaction between the vibrationally excited N-2(X(1)Sigma(g)(+)) and N-2(A(3)Sigma(mu)(+)) is shown to be the pre-eminent excitation mechanism in the short-lived afterglow.