Calculations of V–V Transfer Probabilities in CO–CO Collisions

Abstract

This paper presents detailed calculations of vibration—vibration transfer probabilities in CO–CO collisions including both long-range and short-range interactions. Comparison is made with experimental data, and the results show that the relative contributions of the long- and short-range interactions to the V–V transfer probability depend on energy defect and temperature. Our calculations match the experimental data at 300°K to within 25%; at this temperature the the short-range interactions dominate in determining the transition probability for vibrational energy defects greater than 210 cm−1, while the long-range interactions dominate for smaller defects.

Vibrational energy transfer in near resonance due to dipole–dipole interactions

“…The parabolic path comes out as a solution to scattering by a central repulsive potential [ 121, which dominates the trajectory at small distances of approach, but it does not necessarily imply that it dominates the V-V exchange rate. Small-impact parameters do not necessarily mean overlapping charge distributions, therefore the contribution of short-range forces is still of secondary importance even in this range of b and was not included [13]. Therefore, we assume that the collision event occurs on two straight lines, the colliding molecule comes in straight, undergoes a hard-sphere collision, and rebounds on a straight line.…”

Relaxations vibrationnelle et rotationnelle dans un laser a CO-N2

“…Notons que le calcul des probabilités de transitions par interaction dipôle-dipôle d'après la théorie de SB a été fait pour CO-CO par Jeffers et Kelley [15] et Tam [16] mais ces auteurs n'ont calculé que les probabilités Pf §moyennées sur la rotation et pour notre travail il fallait que la molécule de CO(v, J,) soit dans un niveau de rotation donné J du niveau de vibration v et que la molécule de CO(V, J2) puisse être dans un état excité.…”

Mechanisms of Ionizational Nonequilibrium in Air Plasmas

“…The uncertainties of the rate constants obtained depend on the accuracy of all parameters implemented in the kinetic equations. However accurate V-V values for CO are available and have been satisfactorily modeled theoretically by Jeffers and Kelley [46]. CO and N2 are similar in that they have the same number of electrons, the same molecular weight and nearly the same fundamental vibrational frequency.…”

“…If this interaction is absent, as it is for N2, the short-range repulsive interaction dominates the V-V process. The contribution of the short-range repulsive interaction to the V-V transfer probabilities should be much the same in N2 as in CO. We have done a calculation for N2 based on the shortrange repulsive interaction model presented in [46]. This calculation leads to rate constants of about 6x10" cm /s at 300 K and about 1x10" cm /s at 2000 K. These rate constants has been fitted with an analytical expression of the form given by Eqn.…”