Temperature dependence of the vibrational relaxation rate constants of CO{sub}2 (000{sup left}1) in binary

摘要

The rate constants of intramolecular intermode relaxation of the CO{sub}2 molecule (00{sup}01) in pure CO{sub}2 and in binary mixtures with He, Ar, H{sub}2, O{sub}2, N{sub}2, CO, NO, N{sub}2O, and H{sub}2O were measured in the temperature range 300-1000 K by means of a laser-induced luminescence method. It is shown that these relaxation rate constants K for all the gas mixtures investigated increase with increase in the gas temperature in this range; the most efficient in deactivation of the 00{sup}01 level are the collisions of CO{sub}2 molecules with H{sub}2O molecules; the mechanisms of relaxation of the 00{sup}01 level of CO{sub}2 and their channels depend not only on the temperature but also on the parameters of colliding particles; for each of the colliding partners of the CO{sub}2 molecules there is a certain temperature T{sub}c above which the temperature dependence of K is coordinated with the Landau-Teller dependence, and, moreover, the simpler the structure of the colliding partner of the CO{sub}2 molecule, the higher the temperature T{sub}c. Deviations from these dependences at temperatures T < T{sub}c are attributed to the influence of intermolecular forces of attraction, change of relaxation channels, and formation of molecular clusters. For all the colliding partners of the CO{sub}2 molecules, the interaction radii are determined from the intermolecular potentials of interaction used in the theoretical model.