ATMOSPHERIC CHEMISTRY OF HFC-227CA : SPECTROKINETIC INVESTIGATION OF THE CF3CF2CF2O2 RADICAL, ITS REACTIONS WITH NO AND NO2, AND THE ATMOSPHERIC FATE OF THE CF3CF2CF2O RADICAL

A pulse radiolysis technique was used to study the UV absorption spectrum of CF3CF2CF2O2 radicals, at 230 nm σ = (3.2 ± 0.4) × 10-18 cm2 molecule-1. Rate constants for reactions of CF3CF2CF2O2 radicals with NO and NO2 were k3 > 7 × 10-12 cm3 molecule-1 s-1 and k4 = (7.6 ± 2.4) × 10-12 cm3 molecule-1 s-1, respectively. The rate constant for reaction of F atoms with CF3CF2CF2H was determined by using an absolute rate technique to be (3.6 ± 1.3) × 10-13 cm3 molecule-1 s-1. The atmospheric fate of CF3CF2CF2O radicals is decomposition via C−C bond scission to give CF3CF2 radicals and CF2O. In one bar of SF6 at 296 K, CF3CF2CF2O radicals decompose with a rate > 1.5 × 105 s-1. In their turn CF3CF2 radicals are converted into CF3CF2O radicals which also decompose via C−C bond scission. As part of this work a relative rate method was used to measure k(Cl + CF3CF2CF2H) = (3.4 ± 0.7) × 10-16 and k(F + CF3CF2CF2H) = (3.2 ± 0.8) × 10-13 cm3 molecule-1 s-1. The results are discussed with respect to the atmospheric chem...