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

UV absorption spectra of CF3CClH and CF3CClHO2 radicals have been inve stigated. The CF3CClH spectrum was quantified over the wavelength rang e 225-280 nm. The absorption cross section at 250 nm was (139 +/- 16) x 10(-20) cm(2) molecule(-1). The absorption spectrum for CF3CClO2 was quantified over the wavelength range 225-290 nm, and at 250 nm sigma( 250) (nm) = (258 +/- 30) x 10(-20) cm(2) molecule(-1). The kinetics of the reactions of the peroxy radical CF3CClHO2 with NO and NO2 were st udied and the derived rate constants were k(3) = (1.0 +/- 0.3) x 10(-1 1) cm(3) molecule(-1) s(-1) and k(4) = (6.4 +/- 1.5) x 10(-12) cm(3) m olecule(-1) s(-1), respectively. The self-reaction rate for the CF3CCl HO2 radicals was measured and a value of k(6obs) = (4.4 +/- 0.3) x 10( -12) cm(3) molecule(-1) s(-1) was obtained. The reactions of F atoms w ith CF3CH2Cl and of CF3CClH with O-2 were found to proceed with rate c onstants of k(8) = (2.0 +/- 0.6) x 10(-12) cm(3) molecule(-1) s(-1) an d k(2) = (1.4 +/- 0.1) x 10-(12) cm(3) molecule(-1) s(-1) respectively . The reaction of CF3CClHO2 radicals with NO gives NO2, and by implica tion CF3CClHO radicals, which in the atmosphere (a) react with O-2 to give CF3C(O)Cl and (b) decompose to give, most likely, CF3 radicals an d HC(O)Cl. In 700 Torr of N-2 diluent the rate constant ratio k(O2)/k( diss) = (2.1 +/- 0.4) x 10(-19) cm(3) molecule(-1). As part of the pre sent work, relative rate techniques were used to measure rate constant s for the reactions of Cl and F atoms with CF3CH2Cl of (6.8 +/- 1.2) x 10(-15) and (2.1 +/- 0.5) x 10(-12) cm(3) molecule(-1) s(-1), respect ively. All experiments were performed at 296 +/- 2 K.