Relative rate techniques were used to measure k(Cl + CF 3 CH 2 OCHF 2 ) ) (1.2 ( 0.1) × 10 -14 , k(Cl + CF 3 -CHClOCHF 2 ) ) (5.4 ( 0.5) × 10 -15 , k(Cl + HC(O)OCHF 2 ) ) (2.0 ( 0.2) × 10 -14 , and k(Cl + CF 3 C(O)-OCHF 2 ) < 4 × 10 -17 cm 3 molecule -1 s -1 at 295 K. Cl atoms react with CF 3 CHClOCHF 2 (isoflurane, HCFE-235da2) via H-atom abstraction to give CF 3 C(•)ClOCHF 2 and CF 3 CHClOC(•)F 2 radicals in yields of 92% and 8%. OH radicals react with CF 3 CHClOCHF 2 via H-atom abstraction to give CF 3 C(•)ClOCHF 2 and CF 3 -CHClOC(•)F 2 radicals in yields of 95% and 5%. CF 3 C(•)ClOCHF 2 and CF 3 CHClOC(•)F 2 add O 2 to give peroxy radicals which react with NO to give the alkoxy radicals CF 3 C(O•)ClOCHF 2 and CF 3 CHClOC(O•)-F 2 . The atmospheric fate of CF 3 C(O•)ClOCHF 2 radicals is decomposition via elimination of a Cl atom to give CF 3 C(O)OCHF 2 and is unaffected by the method used to generate the CF 3 C(O•)ClOCHF 2 radicals. Reaction of Cl atoms with CF 3 CH 2 OCHF 2 (HFE-245fa2) proceeds via H-atom abstraction to give CF 3 C(•)-HOCHF 2 radicals in a yield which is indistinguishable from 100%. The fate of the alkoxy radical CF 3 C-(O•)HOCHF 2 is affected by the method in which it is generated. There are two competing fates for CF 3 C(O•)HOCHF 2 radicals formed by the reaction of CF 3 C(OO•)HOCHF 2 with other peroxy radicals; bimolecular reaction with O 2 to give CF 3 C(O)OCHF 2 and unimolecular decomposition via C-C bond scission to give a CF 3 radical and HC(O)OCHF 2 . In contrast, decomposition is the only observable fate of CF 3 C-(O•)HOCHF 2 produced via the CF 3 C(OO•)HOCHF 2 + NO reaction. We ascribe this observation to the formation of vibrationally excited CF 3 C(O•)HOCHF 2 radicals in the CF 3 C(OO•)HOCHF 2 + NO reaction. IR spectra of CF 3 C(O)OCHF 2 and HC(O)OCHF 2 are presented. The results are discussed with respect to the atmospheric chemistry of CF 3 CHClOCHF 2 and other ethers.

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Photodissociation of gaseous CH3COSH at 248 nm by time-resolved Fourier-transform infrared emission spectroscopy: Observation of three dissociation channels J. Chem. Phys. 138, 014302 (2013); 10.1063/1.4768872 Gas-phase photodissociation of CH3COCN at 308 nm by time-resolved Fourier-transform infrared emission spectroscopy J. Chem. Phys. 136, 044302 (2012); 10.1063/1.3674166 I. Three-center versus four-center HCl-elimination in photolysis of vinyl chloride at 193 nm: Bimodal rotational distribution of HCl (v7) detected with time-resolved Fourier-transform spectroscopy

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Trifluoromethyl / Recombination / FTIR / Emission / RatesThe rate constant k 1 for the recombination reaction between CF 3 radicals and O 2 has been measured at 295 K over the pressure range of 2-110 Torr, predominately in N 2 . CF 3 radicals were formed by the uv photolysis of CF 3 I, and their kinetic decay monitored in the presence of NO 2 and O 2 by observing the infrared emission from the products of the CF 3 + NO 2 reaction. The data were combined with higher pressure relative rate constant measurements in the literature to yield a fall off curve with the high pressure limiting value of k 1(∞) = (2.55 ± 0.11) · 10 −12 cm 3 molecule −1 s −1 and the low pressure third body recombination rate constant k 1(0) = (2.5 ± 0.3) · 10 −29 cm 6 molecule −2 s −1 with 2σ quoted errors, and the Troe broadening parameter F c = 0.60. The high pressure limiting value is some 35% lower than the currently recommended value, but is believed to be more reliable because of the far shorter extrapolation to the high pressure limit in the present study compared with previous work. Our data also suggest a reevaluation of the bimolecular rate constant of the CF 3 + Cl 2 reaction to (2.3 ± 0.6) · 10 −14 cm 3 molecule −1 s −1 .