Rate coefficient for the reaction of CCl3 radicals with ozone

✍ Scribed by Takashi Imamura; Hideharu Chono; Kazuhiko Shibuya; Nobuaki Washida

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 108 KB
• Volume: 35
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.10130

✦ Synopsis

Abstract

The rate coefficient for the reaction of CCl~3~ radicals with ozone has been measured at 303 ± 2 K. The CCl~3~ radicals were generated by the pulsed laser photolysis of carbon tetrachloride at 193 nm. The time profile of CCl~3~ concentration was monitored with a photoionization mass spectrometer. Addition of the O~3~–O~2~ mixture to this system caused a decay of the CCl~3~ concentration because of the reactions of CCl~3~ + O~3~ → products (5) and CCl~3~ + O~2~ → products (4). The decay of signals from the CCl~3~ radical was measured in the presence and absence of ozone. In the absence of ozone, the O~3~–O~2~ mixture was passed through a heated quartz tube to convert the ozone to molecular oxygen. Since the rate coefficient for the reaction of CCl~3~ + O~2~ could be determined separately, the absolute rate coefficient for reaction (5) was obtained from the competition among these reactions. The rate coefficient determined for reaction (5) was (8.6 ± 0.5) × 10^−13^ cm^3^ molecule^−1^ s^−1^ and was also found to be independent of the total pressure (253–880 Pa of N~2~). This result shows that the reaction of CCl~3~ with O~3~ cannot compete with its reaction with O~2~ in the ozone layer. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 310–316, 2003