<title>Multiquantum vibrational exchange CO laser kinetic model</title>

Abstract

The new kinetic model of CO laser is developed. The basis of the model is multiquantum vibrational exchange rate constants given by Billing. The full Billing model of multiquantum VV exchange gives rise to satisfactory coincidence with experimental data on vibrational distribution function without any fitted parameters. Computer models of vibrational kinetics for CO containing mixtures are currently widely used in the analysis of problems of highly nonequilibrium vibrational excitation and in investigations of CO lasers. Until now only the single quantum VV exchange models were considered. For single quantum processes CO(v) + CO(u) yields CO(v - 1) + CO(u + 1) the rate constants (RC) are usually calculated using expressions, based on the first order perturbation theory assumptions. The parameters of well known theoretical expressions are fitted thereafter to get the magnitude and vibrational quantum number dependence of RC, measured experimentally. The RC, extended in this way to VV exchange of highly excited molecules, grow rapidly with v,u and exceed gas kinetical RC at rather low v,u > 7 for quasi-resonance exchange. Thus the validity of the first order perturbation theory expressions breaks and vibrational kinetics models using these RC become doubtful for relatively low levels. Nevertheless, these RC were widely used in practical calculations of CO laser kinetics. Their justification was in satisfactory agreement with measurements of vibrational distribution function (VDF), available in the literature.