ELECTRON-IMPACT EXCITATION OF NITRIC-OXIDE UNDER AURORAL CONDITIONS

Excitation of the ground vibrational levels and nine excited electroni c states in NO has been simulated for an IBC II aurora. New electron i mpact excitation cross sections for NO were combined with a measured I BC II auroral secondary electron energy distribution and the electroni c-vibrational populations were determined for conditions of statistica l equilibrium. This model predicts an extended vibrational distributio n in the NO ground electronic state produced by radiative cascade from the many higher lying doublet excited electronic states. In addition to energy storage in the vibrational population of the ground electron ic state, both the a (4) Pi and L' (2) Phi excited electronic states a re predicted to have relatively high number densities in aurora. This extended ground state vibrational distribution is predicted to emit in frared [IR] radiation from 1.3 to 8.2 mu m and most IR bands are predi cted to be stronger than band emission from any of the electonic trans itions.