ATMOSPHERIC FATE OF CF3BR, CF2BR2, CF2CLBR, AND CF2BRCF2BR

The temperature dependent UV absorption cross sections of the haloalkanes CF3Br, CF2ClBr, CF2Br2, and CF2BrCF2Br are reported. The UV absorption cross sections were measured over the temperature range 210 to 296 K and the wavelength range 190 to 320 nm. Upper limit of the rate coefficients for the reactions of OH with CF3Br, CF2Br2, CF2ClBr, and CF2BrCF2Br were also determined using both pulsed photolysis and flow tube techniques. The rate coefficients at 296 K were found to be < 1.2 x 10(-16), < 1.5 x 10(-16), < 5.0 x 10(-16), and < 1.5 x 10(-16) cm3 molec-1 s-1 for CF3Br, CF2ClBr, CF2Br2, and CF2BrCF2Br, respectively. The UV absorption cross-section data and OH reaction rate coefficients of these species were combined with a one-dimensional model to yield atmospheric lifetimes of 65, 16, 3.2, and < 20 years for CF3Br, CF2ClBr, CF2Br2, and CF2BrCF2Br, respectively.