Nightglow and a new band system in molecular oxygen

Abstract

I PROPOSE here that the transition 3Σ+u → 1Δg in O2 is responsible for previously unidentified features in the nightglow from the Earth's atmosphere, and in observations of radiation emitted from recombining atomic oxygen in the laboratory. The transition violates the approximate selection rules ΔS = 0 and ΔΛ = 0, ±1 (ref. 1); it may be compared with the transition 1Δg → 3Σ−g, which, in addition to violating these selection rules, also violates the rigorous selection rule g←/→g for electric dipole radiation, and so proceeds by magnetic dipole radiation2. The transition 3Σ+u → 1Δg may therefore be significantly stronger than the transition 1Δg → 3Σ−g.