Atmospheric Chemistry of HFC-143a: Spectrokinetic Investigation of the CF3CH2O2 Radical, Its Reactions with NO and NO2, and the Fate of CF3CH2O

Article abstract of DOI:10.1021/j100089a026

The ultraviolet absorption spectrum of CF3CH2O2 rradicals, the kinetics of their self-reaction, and their reactions with NO and NO2 have been studied in the gas phase at 296 K using a pulse radiolysis technique.A long path-length Fourier transform infrared technique was used to study the fate of CF3CH2O radicals.Absorption cross sections were quantified over the wavelength range 220-300 nm.At 250 nm, ?(CF3CH2O2) = (2.73 +/- 0.31) * 10^-18 molecule^-1.By monitoring the rate of NO2 formation, k₄ = (1.2 +/- 0.3) * 10^-11 cm³ molecule^-1 s^-1 was found for the reaction of CF3CH2O2 radical with NO.The reaction of CF3CH2O2 radicals with NO gives CF3CH2 radicals.In the atmosphere, >99.3percent of the CF3CH2O radicals react with O2 to give CF3CHO.By monitoring the rate of NO2 decay, k₅ = (5.8 +/- 1.1) * 10^-12 cm³ molecule^-1 s^-1 was found for the reaction of CF3CH2O2 radical with NO2.The results are discussed with respect to the atmospheric chemistry of CF3CH3 (HFC-143a).As a part of the present work, relative rate techniques were used to measure the following rate constants: (2.6 +/- 0.7) * 10^-12 and (2.0 +/- 0.5) * 10^-12 for the reaction of F atoms with CF3CH3, (5.5 +/- 0.3) * 10^-11 for the reaction of F atoms with CF3CH2OH, and (3.6 +/- 0.2) * 10^-17 for the reaction with Cl atoms with CF3CH3 (units of cm³ molecule^-1 s^-1).