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Absolute rate constants for the self reactions of HO 2 , CF 3 CFHO 2 , and CF 3 O 2 radicals and the cross reactions of HO 2 with FO 2 , HO 2 with CF 3 CFHO 2 , and HO 2 with CF 3 O 2 at 295 K
Author(s) -
Sehested Jens,
Møgelberg Trine,
Fagerström Kjell,
Mahmoud Gharib,
Wallington Timothy J.
Publication year - 1997
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/(sici)1097-4601(1997)29:9<673::aid-kin4>3.0.co;2-r
Subject(s) - chemistry , radical , reaction rate constant , radiolysis , decomposition , kinetics , context (archaeology) , photochemistry , analytical chemistry (journal) , organic chemistry , paleontology , physics , quantum mechanics , biology
The kinetics of the self‐reactions of HO 2 , CF 3 CFHO 2 , and CF 3 O 2 radicals and the cross reactions of HO 2 with FO 2 , HO 2 with CF 3 CFHO 2 , and HO 2 with CF 3 O 2 radicals, were studied by pulse radiolysis combined with time resolved UV absorption spectroscopy at 295 K. The rate constants for these reactions were obtained by computer simulation of absorption transients monitored at 220, 230, and 240 nm. The following rate constants were obtained at 295 K and 1000 mbar total pressure of SF 6 (unit: 10 −12 cm 3 molecule −1 s −1 ): k (HO 2 +HO 2 )=3.5±1.0, k (CF 3 CFHO 2 +CF 3 CFHO 2 )=3.5±0.8, k (CF 3 O 2 +CF 3 O 2 )=2.25±0.30, k (HO 2 +FO 2 )=9±4, k (CF 3 CFHO 2 +HO 2 )=5.0±1.5, and k (CF 3 O 2 +HO 2 )=4.0±2.0. In addition, the decomposition rate of CF 3 CFHO radicals was estimated to be (0.2–2)×10 3 s −1 in 1000 mbar of SF 6 . Results are discussed in the context of the atmospheric chemistry of hydrofluorocarbons. © 1997 John Wiley & Sons, Inc.