O2($b^1 \Sigma _g^ +$b1Σg+, υ = 0, 1) relative yields in O(1 D ) + O2 energy transfer

Energy transfer from O(1D) to O2 is the main source of O2($b^1 \Sigma _g^ +$b1Σg+) in vibrational levels υ = 0 and 1 in the Earth's thermosphere. Knowledge of the relative yields for O2($b^1 \Sigma _g^ +$b1Σg+) production in υ = 0 and 1 is essential for a reliable interpretation and modeling of the O2 atmospheric band emissions ($b^1 \Sigma _g^ +$b1Σg+–$X\,^3 \Sigma _g^ -$XΣg−3) from these two vibrational levels. We report laboratory measurements of the relative yields at room temperature. In the experiments, O2($b^1 \Sigma _g^ +$b1Σg+, υ = 0, 1) is generated by O(1D) + O2 collisions following partial photodissociation of O2 at 157.6 nm. O2($b^1 \Sigma _g^ +$b1Σg+, υ = 0, 1) emission detection is used to monitor the temporal evolution of the vibrational level populations. The measured fractional yield for υ = 1 is 0.8 ± 0.1, in contrast with the results of previous studies that indicated dominant O2($b^1 \Sigma _g^ +$b1Σg+, υ = 0) production. A revision is warranted of the values used for these relative yields in atmospheric models.