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Photochemical Properties of Some Cl-Containing Halogenated Alkanes

Orkin, V. L., V. G. Khamaganov, E. E. Kasimovskaya, and A. G. Guschin (2013), Photochemical Properties of Some Cl-Containing Halogenated Alkanes, J. Phys. Chem. A, 117, 5483-5490, doi:10.1021/jp400408y.

Rate constants for the gas-phase reactions of OH radicals with three partially halogenated alkanes, CH3Cl (kMC), CHFClCFCl2 (k122a), and CH2FCFCl2 (k132c), were measured using a discharge flow−electron paramagnetic resonance technique over the temperature range from 298 to 460 K. The temperature dependences of the rate constants can be represented by the expressions kMC(298−460 K) = (3.09 ± 0.94) × 10−12 exp[−(1411 ± 85)/T] cm3molecule−1s−1, k122a(298−460 K) = (1.26 ± 0.24) × 10−12 exp[−(1298 ± 66)/T] cm3molecule−1s−1, and k132c(298− 370 K) = (8.1 ± 2.2) × 10−13 exp[−(1247 ± 89)/T] cm3molecule−1s−1. The atmospheric lifetimes of CH3Cl, CHFClCFCl2, and CH2FCFCl2 due to their reaction with OH were estimated to be 1.6, 3.5, and 4.5 years, respectively. The UV absorption cross sections of halogenated ethanes, CHFClCFCl2, and CH2FCFCl2, were measured at T = 295 K between 190 and 240 nm, as were those for CHCl2CF2Cl (HCFC-122), CHCl2CF3 (HCFC-123), CHFClCF2Cl (HCFC-123a), and CH3CFCl2 (HCFC141b). The atmospheric lifetimes due to stratospheric photolysis were also estimated.

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Upper Atmosphere Research Program (UARP)