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Technical Note: A new mechanism of 15 μm emission in the mesosphere-lower thermosphere (MLT)

R. D. Sharma
2014 Atmospheric Chemistry and Physics Discussions  
Accurate knowledge of the rate as well as the mechanism of excitation of the bending mode of CO<sub>2</sub> is necessary for reliable modeling of the mesosphere-lower thermosphere (MLT) region of the atmosphere. Assuming the excitation mechanism to be thermal collisions with atomic oxygen the rate coefficient derived from the observed 15 &mu;m emission by space-based experiments differ from the laboratory measurements by a factor of 2–4. It is proposed that thermal collisions with
more » ... with N<sub>2</sub>, mediated by a near-resonant rotation to vibration energy transfer process, excite bending mode of CO<sub>2</sub> by transferring energy from high rotational levels of thermal N<sub>2</sub>. Analogy with the excitation of the bending mode of CO<sub>2</sub> by H<sub>2</sub>O, a process important in CO<sub>2</sub> lasers, mediated by a near-resonant rotation-to vibration energy transfer process lends credibility to the hypothesis which has yet to be tested by direct calculations.
doi:10.5194/acpd-14-25083-2014 fatcat:utxkaglgfvhttnhkj2mhl5khn4