The vibrational development of the O2(b¹Σg+-X³Σg−) system in auroras

The vibrational development of the O2 atmospheric band system in auroras has been observed to vary considerably with height. In relation to the N2 first positive bands, the O2 atmospheric 1-1 band increases markedly with height, in agreement with previous observations, whereas bands with 2 ≤ υ′ ≤ 5 show very little change. This suggests that quenching may be much stronger for the υ′ = 1 level than for bands with υ′ ≥ 2; vibrational energy exchange with ground state O2 could produce this effect. Production of the O2¹Σg+ state with υ′ ≤ 5 is discussed, with emphasis being put on the reaction of hot O(¹D) atoms with O2. It is shown that this reaction could produce the observed intensities for the bands with υ′ ≥ 2.