Vibrational Relaxation in Carbon Dioxide

The vibrational excitation of a CO2 molecule in collision with another CO2 molecule is investigated. A derivation of the cross section by means of the method of the distorted waves and the rate of total energy transfer are presented. There are two relaxation processes with different relaxation times related to direct excitation of the bending mode and excitation in series of the valence mode. Experimental results obtained by the author, to be published separately, confirm this conclusion. The experimental relaxation time for the bending vibration was about one-half of the calculated value, which may be considered a fair agreement in view of the uncertainty involved in the interaction potential and of other approximations which had to be introduced into the calculations.