The chain mechanism of ozone destruction by CFCl3 in the 214 nm photolysis of its mixtures with oxygen
✍ Scribed by A. Horowitz; G. Schuster; G. K. Moortgat
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- English
- Weight
- 740 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0538-8066
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✦ Synopsis
Abstract
The effect of CFCl~3~ (0.025–0.200 mbar) addition on the formation of ozone in 214 nm photolysis of oxygen (800–2000 mbar) was investigated. Kinetic analysis of the drastic reduction in ozone formation in the presence of CFCl~3~ shows that it proceeds by a chain mechanism with a chain length of 5.07 ± 0.21(2σ). This chain length is independent of CFCl~3~ and O~2~ pressures as well as incident light intensity and the mechanism of the chain reaction is governed by the Cl generating reactions of ClO radicals. A mechanism based only on the self reaction of these radicals: ClO + ClO → Cl~2~ + O~2~ (7), Cl + ClO~2~ (8), and Cl + OClO (9), followed by fast decomposition of ClO~2~ into Cl and O~2~, predicts a chain length which is considerably lower than the observed value. Incorporation of the reaction CFCl~2~O~2~ + ClO → CFCl~2~O + ClO~2~ (11) in the mechanism satisfactorily accounts for the observed chain length. A lower limit of 3 × 10^−12^ cm^3^ molecule^−1^ s^−1^ for k~11~ is estimated.