Atmospheric Chemistry of HCFC-133a: The UV Absorption Spectra of CF3CClH and CF3CClHO2 Radicals, Reactions of CF3CClHO2 with NO and NO2, and Fate of CF3CClHO Radicals

Article abstract of DOI:10.1021/j100036a018

The UV absorption spectra of CF3CClH and CF3CClHO2 radicals have been investigated.The CF3CClH spectrum was quantified over the wavelenght range 225-280 nm.The absorption cross section at 250 nm was (139+/-16)*10^-20 cm² molecule^-1.The absorption spectrum for CF3CClHO2 was quantified over the wavelength range 225-290 nm, and at 250 nm ?_250nm=(258+/-30)*10^-20 cm² molecule^-1.The kinetics of the reactions of the peroxy radical CF3CClHO2 with NO and NO2 were studied and the derived rate constants were k₃=(1.0+/-0.3)*10^-11 cm³ molecule^-1 s^-1 and k₄=(6.4+/-1.5)*10^-12 cm³ molecule^-1 s^-1, respectively.The self-reaction rate for the CF3CClHO2 radicals were measured and a value of k_6obs=(4.4+/-0.3)*10^-12 cm³ molecule^-1 s^-1 was obtained.The reactions of F atoms with CF3CH2Cl and of CF3CClH with O2 were found to proceed with rate constants of k₈=(2.0+/-0.6)*10^-12 cm³ molecule^-1 s^-1 and k₂=(1.4+/-0.1)*10^-12 cm³ molecule^-1 s^-1, respectively.The reaction of CF3CClHO2 radicals with NO gives NO2, and by implication CF3CClHO radicals, which in the atmosphere (a) react with O2 to give CF3C(O)Cl and (b) decompse to give, most likely, CF3 radicals and HC(O)Cl.In 700 Torr of N2 diluent the rate constant ratio k_O2/K_diss=(2.1+/-0.4)*10^-19 cm³ molecule^-1.As part of the present work, relative rate techniques were used to measure rate constants for the reactions of Cl and F atoms with CF3CH2Cl of (6.8+/-1.2)*10^-15 and (2.1+/-0.5)*10^-12 cm³ molecule^-1 s^-1, respectively.All experiments were performed at 296+/-2 K.