Vibrational energy transfer in CO2–CO mixtures from 163 to 406 °K

Vibrational energy transfer rates in CO₂–CO mixtures have been measured from 163 to 406 °K using the laser excited vibrational fluorescence method. The near resonant V→V transfer step $\mathrm{CO}\text{(v=1)+}{\mathrm{CO}}_2\text{(000)}\begin{array}{c}{k}_e\\ \rightleftharpoons \\ k_e^{\prime }\end{array}\hspace{0.17em}\mathrm{CO}\text{(v=0)+}{\mathrm{CO}}_2\text{(001)+ΔE=−206\hspace{0.17em}}{\mathrm{cm}}^{\text{−1}}$ has been measured in the endothermic direction and after detailed balancing [k_e′=k_e exp(−ΔE/kT)] is in excellent agreement with data taken in the exothermic direction at and above room temperature. V→R,T quenching of the CO₂(001) level by CO₂ and CO has also been studied. The CO₂ self‐relaxation rate reverses in temperature dependence between 250–300 °K with rates becoming progressively faster as temperature decreases. The total quenching rate for CO₂ deactivation in CO₂–CO collisions behaves similarly to the self‐relaxation rate. It was not possible in the present analysis to separate and distinguish the pathways for V→R,T deactivation in equilibrated CO₂–CO mixtures. The cross relaxation terms (CO⁺₂–CO) and (CO⁺–CO ₂) are both expected to be important at low temperatures.