Molecular oxygen absorption continua at 195–300 nm and O₂ radiative lifetimes

With the aid of new calculations on the transition moments between the six lowest states of O 2 , absorption cross sections have been calculated for several oxygen continua, including the A 2 Σ u + ← X 3 Σ g − and A ′ 3 Δ u ← a 1 Δ g systems. Reasonable agreement is achieved with recent experimental results, the comparison indicating an overestimation of the theoretical transition moment for the A‐X system of 20–25%. With this adjustment, the calculated radiative lifetime for the O 2 ( A ) state is 150 ms, in close agreement with the currently used value. The A ′ ← a and A ← X continua cross sections are of similar magnitude, indicating that absorption by O 2 ( a ) cannot be a significant atmospheric process.