The signature profiles of O(1S) In the airglow

Abstract

The spectral line shapes, or signature profiles, of $\text{O(}{}^1\text{S)}$ proceeding from the dissociative recombination of O₂⁺(²π_g) in the upper atmosphere have been optically observed in the nightglow at the geomagnetic equator with a Fabry-Perot spectrometer. The results indicate that the recombination leading to $\text{O(}{}^1\text{S), O(}{}^3\text{P)}$ and 2.79 eV excess energy is favored relative to that leading to $\text{O(}{}^1\text{S), O(}{}^1\text{D)}$ and 0.83 eV. excess energy by at least a factor of 5 to 1. Partial thennalization of the profile was observed indicating energy exchange with the medium. From this, a relaxation time of about 3 sec, or a collision cross section of about 6 × 10⁻¹⁶ cm² can be derived depending on the mechanism invoked for thermalization.