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 spect rum of CF3CF2CF2O2 radicals, at 230 nm sigma = (3.2 +/- 0.4) x 10(-18) cm(2) molecule(-1). Rate constants for reactions of CF3CF2CF2O2 radic als with NO and NO2 were k(3) > 7 x 10(-12) cm(3) molecule(-1) s(-1) a nd k(4) = (7.6 +/- 2.4) x 10(-12) cm(3) molecule(-1) s(-1), respective ly. The rate constant for reaction of F atoms with CF3CF2CF2H was dete rmined by using an absolute rate technique to be (3.6 +/- 1.3) x 10(-1 3) cm(3) molecule(-1) s(-1). The atmospheric fate of CF3CF2CF2O radica ls is decomposition via C-C bond scission to give CF3CF2 radicals and CF2O. In one bar of SF6 at 296 K, into CF3CF2O radicals which also dec ompose via C-C bond scission. As part of this work a relative rate met hod was used to measure k(Cl + CF3CF2CF2H) = (3.4 +/- 0.7) x 10(-16) a nd k(F + CF3CF2CF2H) = (3.2 +/- 0.8) x 10(-13) cm(3) molecule(-1) s(-1 ). The results are discussed with respect to the atmospheric chemistry of HFC-227ca.