ATMOSPHERIC CHEMISTRY OF 1,1,1,2-TETRACHLOROETHANE (CCL3CH2CL) - SPECTROKINETIC INVESTIGATION OF THE CCL3CCLHO2 RADICAL, ITS REACTIONS WITHNO AND NO2, AND ATMOSPHERIC FATE OF THE CCL3CCLHO RADICAL

A pulse radiolysis technique was used to study the ultraviolet absorpt ion spectra of CCl3CClH and CCl3-CClHO2 radicals, the kinetics of the self-reaction of CCl3CClHO2 radicals, and the kinetics of the reaction s of CCl3CClHO2 with NO and NO2 in the gas phase at 296 K. At 240 nm, a(CCl3CClH) = (303 +/- 35) x 10(-20), and at 250 nm, sigma(CCl3CClHO2) = (288 +/- 48) x 10(-20) cm(2) molecule(-1). The observed rate consta nt for the self-reaction of CCl3CClHO2 radicals was (5.0 +/- 1.2) x 10 (-12) cm(3) molecule(-1) s(-1). The rate constants for reactions of CC l3CClHO2 radicals with NO and NO2 were k(3) > 9.0 x 10(-12) and k(4) = (8.9 +/- 2.6) x 10(-12) cm(3) molecule(-1) s(-1), respectively. A lon g path length Fourier transform infrared technique was used to show th at at 295 K in 700 Torr total pressure of air 76 +/- 3% of CCl3CClHO r adicals decompose via C-C bond scission and 24 +/- 3% undergo three-ce nter intramolecular HCl elimination. As part of this work rate constan ts for the reaction of F and Cl atoms with CCl3CH2Cl were determined t o be (6.4 +/- 1.2) x 10(-12) and (5.7 +/- 1.0) x 10(-14) cm(3) molecul e(-1) s(-1), respectively. The results are discussed with respect to t he atmospheric chemistry of tetrachloroethane.