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Atmospheric chemistry of pentachloroethane (CCl3CCl2H): Absorption spectra of CCl3CCl2 and CCl3CCl2O2 radicals, kinetics of the CCl3CCl2O2 + NO reaction, and fate of the CCl3CCl2O radical

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The absorption spectra of CCl3CCl2 and CCl3CCl2O2 radicals and the rate constant for the reaction of CCl3CCl2O2 radicals with NO were measured at 296 ± 2 K using a pulse radiolysis technique. The absorption spectra were measured over the wavelength range 220-400 nm. At 230 nm σ(CCl3CCl2) = (271 ± 84) × 10-20 cm2 molecule-1, and at 240 nm σ(CCl3CCl2O2) = (145 ± 21) × 10-20 cm2 molecule-1. The reaction of F atoms with CCl3CCl2H was determined to have a rate constant of (2.3 ± 1.6) × 10-12 cm3 molecule-1 s-1. The reaction of CCl3CCl2O2 with NO proceeds with a rate constant of (6.2 ± 1.6) × 10-12 cm3 molecule-1 s-1. This reaction gives NO2 and CCl3CCl2O radicals. In the atmosphere, 85% of the CCl3CCl2O radicals eliminate a Cl atom to give CCl3C(O)Cl, and the remaining 15% decompose via C-C bond scission to give CCl3 radicals and COCl2. As part of the present work, relative rate techniques were used to measure rate constants at 296 ± 2 K for the reactions of Cl and F atoms with CCl3CCl2H of (5.2 ± 0.7) × 10-14 and (2.0 ± 0.5) × 10-12 cm3 molecule-1 s-1, respectively.

OriginalsprogEngelsk
TidsskriftJournal of Physical Chemistry
Vol/bind99
Udgave nummer46
Sider (fra-til)16932-16938
Antal sider7
ISSN0022-3654
DOI
StatusUdgivet - 1 jan. 1995

ID: 228191443