Hydrofluorocarbons, many of which contain a CF(3) group, are one of the major substitutes for the chlorofluorocarbons and halons that are being phased out because they contribute to stratospheric ozone depletion. It is critical to ensure that CF(3) groups do not cause significant ozone depletion. The rate coefficients for the key reactions that determine the efficiency of the CF(3) radical as a catalyst for ozone loss in the stratosphere have been measured and used in a model to calculate the possible depletion of ozone. From these results, it is concluded that the ozone depletion potentials related to the presence of the CF(3) group in hydrofluorocarbons are negligibly small.

The formation of a weakly bound adduct in the reaction of OH with DMS-d 6 was observed between 217 and 240 K using the technique of pulsed laser photolysis/pulsed laser-induced fluorescence. The equilibrium constant for this process, OH + DMS-d 6 T OH‚DMS-d 6 , was measured as a function of temperature. The bond strength of this adduct was determined to be 10.7 ( 2.5 kcal mol -1 . The weakly bound adduct was observed to react rapidly with O 2 . The rate constant for the reaction OH‚DMS-d 6 + O 2 f products was determined to be (1.00 ( 0.33) × 10 -12 cm 3 molecules -1 s -1 , independent of pressure and temperature. The atmospheric implications of the formation of this adduct and its reaction with O 2 to the mechanism of DMS oxidation in the atmosphere are discussed.

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