RATE-CONSTANT AND PRODUCTS OF THE REACTION BETWEEN NO3 AND CLO OVER THE TEMPERATURE-RANGE 353-210-K

The rate constant for the reaction between NO3 and ClO has been examined at 1.4 Torr over a range of temperature (T = 353-210 K) by using a newly commissioned discharge-flow apparatus. The rate constant for the reaction has been found to be temperature independent, with a mean value over all temperatures of k1 = (5.0 +/- 1.4) x 10(-13) cm3 molecule-1 s-1 (where the errors represent 95% confidence limits, precision only). The approximate ratios for branching into the following channels have been investigated: NO3 + ClO --> ClOO + NO2 (1a); NO3 + ClO --> OClO + NO2 (1b). At T = 296 K, the ratio k1a/k1 was determined to be 0.9 +/- 0.35. The ratio k1b/k1 was studied at several temperatures and was found to be 0.2 +/- 0.1 at T = 297 K, decreasing with decreasing temperature. No products other than OClO and ClOO (observed indirectly) were detected. Comparisons were made with other studies of the reaction, and some possible implications of OClO formation in polar stratospheres are discussed.