A reexamination of the O I 6300‐Å nightglow

Abstract

In an analysis of 6300‐Å nightglow measurements obtained at Arecibo on the night of April 25/26, 1976, Cogger et al. (1980) reported that model estimates exceeded the observed 6300‐Å intensity by a factor of 2. We have reanalyzed the data in light of newer laboratory and aeronomic determinations of the parameters used to calculate the 6300‐Å intensity and now obtain agreement with the measurements. The rate coefficient for the reaction O + + O 2 → O 2 + + O required to fit the data is 27% smaller at 700 K than previously assumed, but is in agreement with the thermal drift tube measurements of Chen et al. (1978). A specific recombination rate of 1.2×10 7 cm³ s −1 (at 700 K) for production of O(¹ D ) from O 2 + is consistent with the data. This value is somewhat smaller than the recent theoretical calculation of Guberman (1988) for recombination from O 2 + (υ = 0) and may imply that O 2 + is not completely vibrationally relaxed in the nighttime thermosphere. The reaction N(² D ) + O 2 → NO + O(¹ D ) contributes <10% to nightglow 6300‐Å production, even for an assumed O(¹ D ) yield of unity. Quenching of O(¹ D ) by O(³ P ) and the larger transition probabilities suggested by Abreu et al. (1986) result in calculated 6300‐Å intensities virtually indistinguishable from those obtained using the rate coefficients of Link et al. (1981). This suggests that it will be difficult to verify O(¹ D ) quenching by atomic oxygen using nightglow measurements.