CALCULATED RATE CONSTANTS FOR THE REACTION CLO + O -] CL + O2 BETWEEN 220 AND 1000-K

The results of classical trajectory calculations are presented for the reaction ClO + O → Cl + O2. This reaction is an important step in the chlorine-catalyzed destruction of ozone which is thought to occur in the stratosphere. Rate constants have been calculated for temperatures between 220 and 1000 K. The calculated rate constant is 4.36 × 10-11 exp(-191/T) cm3 molecule-1s-1. Its value at 300 K is(2.3 ± 0.2) × 1011 cm3 molecule-1 s-1, which is within a factor of two of the recent experimental measurements. The calculated activation energy of 0.38 kcal/mole is in excellent agreement with the experimental value of 0.44 kcal/mole determined by Clyne and Nip and provides support for their measurements. The calculations were performed using both the quasi-classical and phase space trajectory sampling methods. The empirical potential energy surface used in the calculations was constructed to fit experimental data for ClO, O2 and ClOO molecules. Other important features of this potential surface, such as the barrier to reaction, were varied systematically and calculations were performed for a range of conditions to determine the best" theoretical rate constants. The present results demonstrate how classical trajectory methods can be applied to the determination of activation energies and other kinetic data for important atmospheric reactions. © 1979."