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

Abstract

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 CO(v=1)+CO2(000)ke⇌ke′ CO(v=0)+CO2(001)+ΔE=−206 cm−1 has been measured in the endothermic direction and after detailed balancing [ke′=ke 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.