Emission from atomic nitrogen produced by electron impact on nitrogen molecules

Abstract

Absolute optical emission cross sections have been measured for transitions of the N atom in the wavelength range 3800–7000 Å originating from 51 terms of the N (2p2nl) configurations with n from 4 to 9 produced by electron-impact dissociation of the N2 molecule. The incident electron energy ranges from threshold to 450 eV. The excitation functions show a broad maximum at about 85 eV and a shoulder structure near 35 eV. Near the threshold energy the formation of the excited nitrogen atoms is believed to be largely due to dissociative excitation through the repulsive part of Rydberg states of N2 that converge to the N+2(D 2Πg) ion. An abrupt increase in the slope of the excitation functions at 5 eV above threshold is suggestive of the opening up of higher-energy channels of dissociative excitation. Combining the measured optical emission cross sections with theoretical transition probabilities calculated by a Hartree–Fock procedure with configuration interaction, optical cross sections have been obtained for a number of long-wave infrared emission lines of the N atom excited by electron-impact dissociation of the N2 molecule.