Accession Number : AD0634437

Title :   POPULATION DISTRIBUTIONS DURING VIBRATIONAL RELAXATION OF DIATOMIC GASES,

Corporate Author : CORNELL AERONAUTICAL LAB INC BUFFALO N Y

Personal Author(s) : Rich, J. W. ; Rehm,R. G.

Report Date : APR 1966

Pagination or Media Count : 32

Abstract : A master equation analysis for the vibrational relaxation of a diatomic gas is presented, including the effects of near-resonance exchange of vibrational energy between colliding oscillators. It is found that the mechanism of rapid near-resonance exchange of vibrational energy among the diatomic species tends to maintain a quasi-steady state vibrational population distribution during the relaxation of a pure gas. The specific functional form of this quasi-steady state distribution is determined from a perturbation analysis of the master equation. A detailed analyses is also given of the relaxation equations for the case of equi-distant vibrational energy level spacing. It is found that when the diatomic gas is diluted by an inert to the extent that oscillator-oscillator exchange collisions no longer influence relaxation, the vibrational population distribution can depart markedly from the Boltzmann form. Whenever exchange collisions predominate, however, it is found that a near-Boltzmann distribution is preserved, regardless of the form of the vibration-translation transition probabilities, and the energy relaxation equation does not differ greatly from the Landau-Teller result. (Author)

Descriptors :   (*DIATOMIC MOLECULES, RELAXATION TIME), (*MOLECULAR ENERGY LEVELS, STATISTICAL DISTRIBUTIONS), VIBRATION, EXCITATION, EQUATIONS, PERTURBATION THEORY

Subject Categories : Atomic and Molecular Physics and Spectroscopy
      Quantum Theory and Relativity

Distribution Statement : APPROVED FOR PUBLIC RELEASE