ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A laser flash photolysis-resonance fluorescence technique has been employed to study the kinetics of the important stratospheric reactions Cl(2PJ) + O3 → ClO + O2 and Br(2P3/2) + O3 → BrO + O2 as a function of temperature. The temperature dependence observed for the Cl(2PJ) + O3 reaction is nonArrhenius, but can be adequately described by the following two Arrhenius expressions (units are cm3 molecule-1 s-1, errors are 2σ and represent precision only): k1(T) = (1.19 ± 0.21) × 10-11 exp [(-33 ± 37)/T] for T = 189-269K and k1(T) = (2.49 ± 0.38) × 10-11 exp[(-233 ± 46)/T] for T = 269-385 K. At temperatures below 230 K, the rate coefficients determined in this study are faster than any reported previously. Incorporation of our values for k1(T) into stratospheric models would increase calculated ClO levels and decrease calculated HCl levels; hence the calculated efficiency of ClOx catalyzed ozone destruction would increase. The temperature dependence observed for the (2P3/2) + O3 reaction is adequately described by the following Arrhenius expression (units are cm3 molecule-1 s-1, errors are 2σ and represent precision only): k2(T) = (1.50 ± 0.16) × 10-1 exp[(-775 ± 30)/T] for T = 195-392 K. While not in quantitative agreement with Arrhenius parameters reported in most previous studies, our results almost exactly reproduce the average of all earlier studies and, therefore, will not affect the choice of k2(T) for use in modeling stratospheric BrOx chemistry.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/kin.550220407
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