TEMPERATURE-JUMP AND TRAJECTORY STUDIES OF THE QUENCHING OF CO2(010) BY ATOMIC OXYGEN

A new variant of the temperature-jump method has been used to measure the rate of quenching of CO2(010) by O(3P). The value found for the ra te constant at room temperature is 1.2 +/- 0.2 x 10(-12) cm3 molecule- 1 s-1, in good agreement with a previous laboratory study. Our traject ory calculations show that such a large value of the room-temperature rate constant is not explicable in terms of an impulsive (Landau-Telle r) mechanism but can be understood in terms of a curve-crossing (Nikit in) mechanism. However, the impulsive mechanism is still required to a ccount for the strong temperature dependence of previous high-temperat ure, shock-tube results. Preliminary measurements of the rate of quenc hing of N2O(010) by O(3P) give a rate constant value similar to that f ound for CO2, which implies that formation of a bound triplet state of CO3 plays very little part in the quenching process for CO2(010).