Near-resonant vibration-to-vibration energy transfer in the NO+-N2 collisions

Vibrational energy transfer in O2(v = 2-8)-O2(v = 0) collisions

Starting with multipolar-multipolar interaction for intermolecular potential we have carried out a calculation of rate coefficients for transfer of one quantum of vibrational energy upon impact of O(2)(2 < or = v < or = 8) with O(2)(v = 0) as a function of temperature (150 K < or = T < or = 450 K). The equations for energy transfer, in the second order of perturbation theory, mediated by isotropic and anisotropic dispersion interactions, are derived. None of the parameters appearing in the calculation were adjusted to obtain agreement with the experimentally measured rate coefficients. The results of the calculation are compared with experimentally measured room temperature rate coefficients of the disappearance of O(2)(v) upon collision with O(2)(v = 0). The agreement is found to be good for the disappearance of O(2)(v = 3) and O(2)(v = 5). For O(2)(v = 2) the calculation gives a larger rate coefficient than the measured value, while for O(2)(v = 4) it gives a smaller value than obtained by measurement. For O(2)(v = 8) it agrees with one measurement and gives a value smaller than another measurement and a calculation.

Near-resonant energy transfer from highly vibrationally excited OH to N2

The probability per collision P(T) of near-resonant vibration-to-vibration energy transfer (ET) of one quantum of vibrational energy from vibrational levels nu=8 and nu=9 of OH to N(2)(nu=0), OH(nu)+N(2)(0)-->OH(nu-1)+N(2)(1), is calculated in the 100-350 K temperature range. These processes represent important steps in a model that explains the enhanced 4.3 microm emission from CO(2) in the nocturnal mesosphere. The calculated energy transfer is mediated by weak long-range dipole-quadrupole interaction. The results of this calculation are very sensitive to the strength of the two transition moments. Because of the long range of the intermolecular potential, the resonance function, a measure of energy that can be efficiently exchanged between translation and vibration-rotation degrees of freedom, is rather narrow. A narrow resonance function coupled with the large rotational constant of OH is shown to render the results of the calculation very sensitive to the rotational distribution, or the rotational temperature if one exists, of this molecule. The calculations are carried out in the first and second orders of perturbation theory with the latter shown to give ET probabilities that are an order of magnitude larger than the former. The reasons for the difference in magnitude and temperature dependence of the first- and second-order calculations are discussed. The results of the calculations are compared with room temperature measurements as well as with an earlier calculation. Our calculated results are in good agreement with the room temperature measurements for the transfer of vibrational energy for the exothermic OH(nu=9) ET process but are about an order lower than the room temperature measurements for the exothermic OH(nu=8) ET process. The cause of this discrepancy is explored. This calculation does not give the large values of the rate coefficients needed by the model that explains the enhanced 4.3 microm emission from CO(2) in the nocturnal mesosphere.