REACTION KINETICS OF O plus ClO yields Cl plus O₂ BETWEEN 252-347 K.

A discharge flow system with laser magnetic resonance (LMR), resonance fluorescence (RF), and resonance absorption (RA) detection axes is used to study the kinetics of the title reaction which has attracted a great deal of interest due to its role as the rate limiting step in the chlorine-catalyzed destruction of ozone in the stratosphere. Pseudo-first-order decays of O in excess ClO and of ClO in excess O agree very well and yield a rate constant of (3. 5 plus or minus 0. 5) multiplied by 10** minus **1**1 cm**3 molecule** minus **1 s** minus **1 near 300 K, with no discernable temperature dependence over the range 252-347 K. Both reactants, and for some experiments the Cl atom product, are detected directly with high sensitivity. Experiments are done both in helium and in argon, and the cited uncertainties include an estimate of systematic errors at the 2 sigma or 95% confidence level.