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Vibrational Relaxation Equation for Polyatomic Gases and Its Application to CO 2

1971; Physical Society of Japan; Volume: 30; Issue: 5 Linguagem: Inglês

10.1143/jpsj.30.1467

1347-4073

Yukinori Sato, Soji Tsuchiya,

Phase Equilibria and Thermodynamics

The vibrational relaxation equation for polyatomic gases is formulated in consideration of the translation-vibration and the vibration-vibration energy transfers. The multi-quanta transitions of vibrational states and the simultaneous couplings among any numbers of vibrational modes are allowed in the vibrational energy transfers. On the basis of this relaxation equation, the energy relaxation of each vibrational mode in CO 2 is analyzed. The effect of the V – V couplings between mode ν 3 and modes ν 1 +ν 2 on the relaxation of mode ν 1 (ν 2 ) is not appreciable due to the small vibrational heat capacity of mode ν 3 , and the apparent relaxation rate for mode ν 1 (ν 2 ) is nearly equal to a mean rate constant K ∞ of the T – V processes of modes ν 1 and ν 2 . If the rate of the intramolecular V – V couplings of mode ν 3 with modes ν 1 +ν 2 is comparable to or larger than K ∞ , the apparent relaxation rate of mode ν 3 is also very close to K ∞ . This is the reason why a multiple relaxation has not been found experimentally in CO 2 .