Chemical excitation of O₂(¹Δg) in auroras

If about 50% of the O2 is left in the ¹Δ state, the reaction O2+ + NO → NO+ + O2 may generate as much O2(¹Δ) in an aurora as electron impact of O2 by secondary electrons (Cartwright et al., 1972). Together, these processes may yield approximately one O2(¹Δ) molecule per ion pair formed in the aurora. Stimulated emission of 1.27-μ radiation by electron collisions with the normal O2(¹Δ) nightglow layer is seen as a copious but improbable source of 1.27-μ emissions in auroras. The importance of the temporal history and of the temperature for auroral generated O2(¹Δ) is briefly discussed.