Temperature Dependence of the Collisional Removal of O 2 (A³Σ u + , υ=9) with O 2 and N 2
The temperature dependence of the collisional removal of O 2 molecules in the υ=9 level of the A³Σ u + electronic state has been studied for the colliders O 2 and N 2 , over the temperature range 150 to 300 K. In a cooled flow cell, the output of a pulsed dye laser excites the O 2 to the υ=9 level o...
Saved in:
Published in | Geophysical research letters Vol. 24; no. 6; pp. 643 - 646 |
---|---|
Main Authors | , |
Format | Journal Article |
Language | English |
Published |
15.03.1997
|
Online Access | Get full text |
Cover
Loading…
Summary: | The temperature dependence of the collisional removal of O
2
molecules in the υ=9 level of the A³Σ
u
+
electronic state has been studied for the colliders O
2
and N
2
, over the temperature range 150 to 300 K. In a cooled flow cell, the output of a pulsed dye laser excites the O
2
to the υ=9 level of the A³Σ
u
+
state, and the output of a time‐delayed second laser monitors the temporal evolution of this level via a resonance‐enhanced ionization. We find the thermally averaged removal cross section for O
2
collisions is constant (∼10 Ų) between room temperature and 200 K, then increases rapidly with decreasing temperature, doubling by 150 K. In contrast, the N
2
cross section at 225 K is ∼8% smaller and gradually increases to a value at 150 K that is ∼60% larger than me room temperature value. The difference between the temperature dependence of the O
2
and N
2
collision cross section implies that the removal by oxygen becomes more important at the lower temperatures found in the mesosphere, but removal by N
2
still dominates. |
---|---|
ISSN: | 0094-8276 1944-8007 |
DOI: | 10.1029/97GL00547 |