Transfer of Vibrational Energy From O2 to Symmetric Stretch of CO2

Models of 15 micron emission, an important cooling mechanism in the lower thermosphere, require a rate coefficient for the excitation of the bending mode (ν2) of CO2 by atomic oxygen that is 2-3 times larger than that measured in the laboratory. This has motivated us to look for other mechanisms for energy deposition in the ν2 mode. Since the bending mode is strongly coupled to the symmetric stretch mode (ν1) due to Fermi resonance the deposition of energy in the latter mode is equivalent to deposition in the former mode. There are several mechanisms for production of vibrationally excited O¬2 in the lower thermosphere. In this talk we present a calculation of the rate of energy transfer from O2 (band origin at 1556 cm-1) to the symmetric stretch (ν1) mode of CO2 (band origin at 1388 cm-1) and discuss its feasibility as a cooling mechanism.