Atmospheric Chemistry of Pentachloroethane (CCl3CCl2H): Absorption Spectra of CCl3CCl2 and CCl3CCl2O2 Radicals, Kinetics of the CCl3CCl2O2 + NO Reaction, and Fate of the CCl3CCl2O Radical

Article abstract of DOI:10.1021/j100046a019

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 ?(CCl3CCl2) = (271 +/- 84)E-20 cm² molecule^-1, and at 240 nm ?(CCl3CCl2O2) = (145 +/- 21)E-20 cm² molecule^-1.The reaction of F atoms with CCl3CCl2H was determined to have a rate constant of (2.3 +/- 1.6)E-12 cm³ molecule^-1 s^-1.The reaction of CCl3CCl2O2 with NO proceeds with a rate constant of (6.2 +/- 1.6)E-12 cm³ molecule^-1 s^-1.This reaction gives NO2 and CCl3CCl2O radicals.In the atmosphere, 85percent of the CCl3CCl2O radicals eliminate a Cl atom to give CCl3C(O)Cl, and the remaining 15percent 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)E-14 and (2.0 +/- 0.5)E-12 cm³ molecule^-1 s^-1, respectively.