UV ABSORPTION-SPECTRA, KINETICS, AND MECHANISMS OF THE SELF REACTION OF CF3O2 RADICALS IN THE GAS-PHASE AT 295-K

The ultraviolet absorption spectrum and the self reaction kinetics of CF3O2 radicals have been studied in the gas phase at 298 K using the pulse radiolysis technique. Long pathlength Fourier transform infrared (FTIR) spectroscopy was used to identify and quantify reaction products. Absorption cross sections were quantified over the wavelength range 215-270 nm. The measured cross section at 230 nm was; sigma(CF3O2(230 nm) = (2.06 +/- 0.40) X 10(-18) cm2 molecule-1 Errors represent statistical (2sigma) together with our estimate of potential systematic errors. The absorption cross section data were then used to derive the observed self reaction rate constant for reaction (1), defined as -d[CF302]/dt = 2k(obs)[CF3O2]2 (1) CF3O2 + CF3O2-->products k(lobs) = (3.6 +/- 0.9) X 10(-12) cm3 molecule-1 s-1. The only carbon containing product observed by FTIR spectroscopy was CF3OOOCF3. Consideration of the loss of CF3O2 radicals to form the trioxide CF3OOOCF3 allows derivation of the true bimolecular rate constant for reaction (1); k1 = (1.8 +/- 0.5) X 10(-12) cm3 molecule-1 s-1. These results are discussed with respect to previous studies of the absorption spectra of peroxy radicals, the kinetics, and mechanisms of their self reaction.