Nightglow vibrational distributions in the A³?_u⁺ and A'³?_u states of O₂ derived from astronomical sky spectra

T. G. Slanger (1) , P. C. Cosby (1) , D. L. Huestis (1) , A. M. Widhalm (2)

1 Molecular Physics Laboratory
2 Department of Physics and Astronomy [USC, Los Angeles]

Astronomical sky spectra from the Keck I telescope on Mauna Kea have been used to obtain vibrational distributions in the O₂A³?_u⁺) and O₂(A'³?_u) states from rotationally-resolved Herzberg I and Chamberlain band emissions in the terrestrial nightglow. The A³?_u⁺ distribution is similar to that presented in earlier publications, with the exception that there is significant population in the previously undiscerned v=0 level. The vibrational distributions of the A'³?_u and A³?_u⁺ states are essentially the same when comparison is made in terms of the level energies. The intensity of Chamberlain band emission at the peak of the distribution is about one-fourth that of the Herzberg I emission, as previously shown, and may be related primarily to radiative efficiency. The peaks in both population distributions are about 0.25eV below the O(³P)+O(³P) dissociation limit. We compare these Herzberg state distributions with that of the O₂(b¹?_g⁺) state, concurring with others that the intense nightglow emission associated with b¹?_g⁺(v=0) is a reflection of direct transfer from the Herzberg states. This process takes place following O₂ collisions, with simultaneous production of very high a¹?_g and b¹?_g⁺ vibrational levels.

Domaines: Océan, Atmosphère; Sciences de la Terre

T. G. Slanger, P. C. Cosby, D. L. Huestis, A. M. Widhalm. Nightglow vibrational distributions in the A³?_u⁺ and A'³?_u states of O₂ derived from astronomical sky spectra. Annales Geophysicae, 2004, 22 (9), pp.3305-3314. ⟨hal-00317660⟩