Excited oxygen states in the Venus nightglow1.

In the absence of solar radiation, the most common photoexcitation process in the terrestrial planets results from atom recombination. Thus, in the Mars and Venus atmospheres recombination of O(3P) + O(3P) and O(3P) + N(4S) leads to emissions of excited states of O2 and NO, respectively. However, in the Earth's atmosphere there are ionospheric emissions that depend on interactions of charged species, for example, the oxygen red and green lines arising from dissociative recombination (DR) of . In the case of the CO2 planets, the predominant ionospheric ion is also , so that in principle DR is important in that environment, where the markers would also be the red and green lines. Whether these can be detected depends on DR rates and the radiating efficiencies of these species. In this report we discuss the history of green line detection in the Venus nightglow as well as the observations of excited O2 molecules, and the lack of appearance of the O2 (b-X) Atmospheric 0-0 band. [ABSTRACT FROM AUTHOR]