ATMOSPHERIC CHEMISTRY OF 1,1,1-TRICHLOROETHANE - UV ABSORPTION-SPECTRA AND SELF-REACTION KINETICS OF CCL3CH2 AND CCL3CH2O2 RADICALS, KINETICS OF THE REACTIONS OF THE CCL3CH2O2 RADICAL WITH NO AND NO2, AND THE FATE OF THE ALKOXY RADICAL CCL3CH2O

A pulse radiolysis technique was used to measure the UV absorption spe ctra of CCl3CH2 and CCl3CH2O2 radicals over the range 220-300 nm. At 2 20 nm, sigma(CCl3CH2) = (9.4 +/- 1.1) x 10(-18) cm(2) molecule(-1); at 250 nm, sigma(CCl3CH2O2) = (2.9 +/- 0.3) x 10(-18) cm(2) molecule(-1) . The observed self-reaction rate constants, defined as -d[CCl3CH2]/dt = 2k(4)[CCl3CH2] and -d[CCl3CH2O2]/dt = 2k(5obs)[CCl3CH2O2](2), were k(4) = (9.1 +/- 1.1) x 10(-12) and k(5obs) = (4.7 +/- 1.6) x 10(-12) c m(3) molecule(-1) s(-1). The reaction of CCl3CH2O2 radicals with NO gi ves CCl2CH2O radicals. In the atmosphere, >96% of the CCl3CH2O radical s react with O-2 to give CCl3CHO. The rate constants for the reactions of CCl3CH2O2 radicals with NO and NO2 were determined to be k(6) grea ter than or equal to 6.1 x 10(-12) cm(3) molecule(-1) s(-1) and k(7) = (6.5 +/- 0.4) x 10(-12) cm(3) molecule(-1) s(-1), respectively. As a part of this work, the rate constant for the reaction between F atoms and CCl3CH3 was determined to be k(3) = (6.8 +/- 1.5) x 10(-12) cm(3) molecule(-1) s(-1). A relative rate technique was used to measure rate constants for the reactions of Cl atoms with: CCl3CH3, (9.9 +/- 2.0) x 10(-15); CCl3CHO, (6.0 +/- 1.3) x 10(-12); and CCl3CH2OH (3.0 +/- 0. 6) x 10(-12) (units of cm(3) molecule(-1) s(-1)) at 296 K. Results are discussed in the context of the atmospheric chemistry of 1,1,1-trichl oroethane.