Electron impact excitation of the N₂⁺Meinel band

Abstract

The authors have measured rates for the excitation of vibrational levels 2-7 of the A 2 Pi u state of N2+ by electron impact on N2 relative to each other and to N2+(B 2 Sigma u+, v'=0). These rates are consistent with Franck-Condon factors for ionisation, previous laboratory measurements and high-altitude auroral observations. The total cross section for production of the Nu+(A 2 Pi 2) state by the impact of electrons between 2.5 and 6.0 kV on N2 is 4.1+or-0.7 times as large as the production rate for the B state. Given the invariance with energy in the ratio of the electron impact cross sections for A-state production to those for B-state production at energies greater than 50 eV, the result implies a total cross section for A-state production at 100 eV of (1.15+or-0.23)*10-16 cm2.