Vibration - vibration energy transfer in diatomic molecules

Abstract

PART A Vibration-Vibration Energy Transfer in Iodine Molecules Vibration-Vibration energy exchange probabilities between iodine molecules ($X^1Σ_g^+$) have been calculated by use of the solution of the time-dependent Schrodinger equation. The interaction potential is constructed by summing four orientation averaged atom-atom interactions. One-quantum probabilities $P_{v-1,1}^{v,0} (T)$ for v-1,1→v,0 are found to be very large in a temperature range of 100-3000K. At lower temperatures, the approximate linear relation $P_{v-1,1}^{v,0}$ (T)~$vp_{0,1}^{1,0}$ (T) holds. When v is small, the probability increases linearly with temperature. Multiquantum transitions v,0 → v-n,n with n＞1 are found to be negligible near room temperature, but they become quite efficient at higher temperatures. Energy exchange probabilities are formulated in infinite order and their reduction to first-order expressions are discussed in detail. The effects of molecular attraction are also discussed. The effects of simultaneous rotational transition has not been included; instead, we have discussed the effects of molecular orientation. PART B The Vibrational Relaxation Rate Coefficients of NO(v=1-7) by $O_2$ The vibrational relaxation processes $NO(v) + O_2$→$NO(v-1) + O_2$ for v=1-7 have been investigated by use of the solution of the time-dependent Schrodinger equation of energy transfer probabilities. The rate coefficients increase monotonically with v, which is very compatible with experimental data. Furthermore, the relaxation mechanism is nearly interpreted by V-V energy transfer.