Deactivation of Vibrationally Excited Carbon Dioxide (001) by Collisions with Carbon Monoxide

Abstract

The rate constants associated with the deactivation of vibrationally excited CO2*(001) by collisions with CO have been experimentally determined from 300 to 900°K by a laser fluorescence method. These reactions involving CO considered were CO2*(001)+CO⇆ lim k2k1CO2+CO*(υ = 1), CO2*(001)+CO→ lim kCOCO2(ν1, ν2)+CO, CO*(υ = 1)+CO2→ lim k4CO+CO2(ν1, ν2), where CO2(ν1, ν2) is an unidentified product state. Within experimental error the rate constant k1 increases linearly with temperature T(°K) from a value of 5.7 × 103 torr−1·sec−1 at room temperature to a value of 11.2 × 103 torr−1·sec−1 at 900°K. From 500 to 900°K the rate constant kCO(torr−1·seconds−1) varies with temperature as log10kCO = A − BT−1/3, with A = 6.61 and B = 31.6. From 300 to 500°K the measured values of kCO are greater than those corresponding to the cited relation. The rate constant k4 was found to be negligible compared to kCO. The probability per collision of vibrational energy transfer from CO2*(001) to CO(υ = 0) was computed by a theory involving long range forces. The calculated probabilities, using only multipolar interaction and only exponential repulsive interaction, are in equally good agreement with the probabilities deduced from measurement of R1, the transfer rate constant in the exothermic direction.