The yield of O2(b1Σ+g,υ=O) produced by quenching of O2(A3Σ+u,υ=8) by O2

Abstract The fraction α of O 2 (b 1 Σ + g ,υ=O) molecules formed when O 2 (A 3 Σ + g ,υ=8) is quenched by molecular oxygen was obtai by comparison of the intensities of the excitation spectra of O 2 (A 3 Σ + u ,υ=8) and O 2 (b 1 Σ + u ,υ=O), both observed vi the O 2 (b→ X, (0,0) emission at λ = 762 nm. The result is α=0.25±0.09. An approximate value for the fraction of O 2 (b 1 Σ + g ) formed by quenching by N 2 , β, is 0.75. The consequences for the contribution to the excitation of O 2 (b 1 Σ + g ,υ=O) in the nightlow of the lower thermosphere of the Earth are discussed.