855719-07-2Relevant academic research and scientific papers
Absolute rate constants for the self reactions of HO2, CF3CFHO2, and CF3O2 radicals and the cross reactions of HO2 with FO2, HO2 with CF3CFHO2, and HO2 with CF3O2 at 295 K
Sehested,Mogelberg,Fagerstrom,Mahmoud,Wallington
, p. 673 - 682 (2007/10/03)
The kinetics of the self-reactions of HO2, CF3CFHO2, and CF3O2 radicals and the cross reactions of HO2 with FO2, HO2 with CF3CFHO2, and HO2 with CF3O2 radicals, were studied by pulse radiolysis combined with time resolved UV absorption spectroscopy at 295 K. The rate constants for these reactions were obtained by computer simulation of absorption transients monitored at 220, 230, and 240 nm. The following rate constants were obtained at 295 K and 1000 mbar total pressure of SF6 (unit: 10-12 cm3 molecule-1 s-1): k(HO2+HO2) = 3.5±1.0, k(CF3CFHO2+CF3CFHO2) = 3.5±0.8, k(CF3O2+CF3O2) = 2.25±0.30, k(HO2+FO2) = 9±4, k(CF3CFHO2+HO2) = 5.0±1.5, and k(CF3O2+HO2) = 4.0±2.0. In addition, the decomposition rate of CF3CFHO radicals was estimated to be (0.2-2)×103 s-1 in 1000 mbar of SF6. Results are discussed in the context of the atmospheric chemistry of hydrofluorocarbons.
Flash Photolysis-Time-Resolved UV Spectroscopy of the CF3CFHO2 Self-Reaction
Maricq, M. Matti,Szente, Joseph J.
, p. 10862 - 10868 (2007/10/02)
The self-reaction of CF3CFHO2 has been studied via time-resolved ultraviolet spectroscopy over the temperature range 211-372 K.The absorption spectrum of CF3CFHO2 extends from 190 to 275 nm with a maximum cross section of (5.2 +/- 0.3) * 10-18 cm2 molecule-1 at 213 nm.The UV absorbance of the reaction mixture decreases and shifts to the blue as the reaction progresses.This is consistent with the CF3CFHO2 self-reaction producing CF3CFHO, the alkoxy radical then decomposing to yield CF3, which adds molecular oxygen to form CF3O2.The CF3CFHO2 self-reaction has a negative temperature dependence with rate constant given by k1 = (7.8 +/- 1.3) * 10-13 e(605+/-40)/T cm3 s-1.The rate of alkoxy radical dissociation, at 230 Torr of total pressure, is k2a = (3.7 +/- 0.7) * 107 e-(2200+/-150)/T s-1.The rate constants for CF3O2 reaction with CF3CFHO2 and itself are determined to be k8 = (8 +/- 3) * 10-12 and k9 = (1.8 +/- 0.5) * 10-12 cm3 s-1, respectively, at 297 K.
