Collisional removal of O2(b1Σg+, υ = 1) by O2 at thermospheric temperatures
Abstract
Collisional removal of O2(b1Σg+, υ = 1) by O2 is investigated at temperatures relevant to the lower thermosphere. A two-laser technique is used, in which the visible output of the first laser directly excites ground-state oxygen molecules to the υ = 1 level of the b1Σg+ state and the ultraviolet output of the second laser probes the O2(b1Σg+, υ = 1) population by resonantly enhanced multiphoton ionization via the υ = 4 level of the d1Πg Rydberg state. The collisional removal rate coefficient increases with temperature by a factor of five in the range 300-1000 K, with a value of about 8 × 10-11 cm3 s-1 near 1000 K. Given the magnitude of the rate coefficient, the removal by O2 plays a dominant role in controlling the population of O2(b1Σg+, υ = 1) in the mesosphere and lower thermosphere at altitudes below 150 km and likely continues to be an important removal pathway at altitudes up to about 200 km.
- Publication:
-
Journal of Geophysical Research (Space Physics)
- Pub Date:
- March 2005
- DOI:
- 10.1029/2004JA010860
- Bibcode:
- 2005JGRA..110.3308P
- Keywords:
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- Atmospheric Composition and Structure: Airglow and aurora;
- Atmospheric Composition and Structure: Chemical kinetic and photochemical properties;
- Atmospheric Composition and Structure: Middle atmosphere: composition and chemistry;
- Atmospheric Composition and Structure: Thermosphere: composition and chemistry;
- oxygen nightglow;
- excited oxygen;
- atmospheric band;
- energy transfer;
- collisional removal;
- O<SUB>2</SUB> REMPI detection