UV absorption spectra, kinetics, and mechanisms of the self reaction of CF₃O₂ radicals in the gas phase at 295 K

Abstract

The ultraviolet absorption spectrum and the self reaction kinetics of CF302 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; a,-no2(230 nm) = (2.06 2 0.40) X lo-'* cm2 molecule-' Errors represent statistical (2a) 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 (I), defined as -d[CF302]/dt = 2ko~s[CF302]2 (1) CF302 + CF3O2 -products kj& = (3.6 2 0.9) X lo-'' cm3 molecule-' 5-l. The only carbon containing product observed by FTIR spectroscopy was CF3000CF3. Consideration of the loss of CF302 radicals to form the trioxide CF3000CF3 allows derivation of the true bimolecular rate constant for reaction (1); k l = (1.8 2 0.5) X cm3 molecule-' s-l. These results are discussed with respect to previous studies of the absorption spectra of peroxy radicals, the kinetics, and mechanisms of their self reaction. 0 1992 John Wiley & Sons, Inc.

The reaction of photochemically generated CF3O radicals with CO

“…It is believed that the formation of CO 2 proceeds according to the same mechanism which occurs in air, and that CF 2 O is formed by heterogeneous reactions of CF 3 O radicals on the reactor walls [29,30]. additional experiments.…”

“…In reaction (3b) CF 3 radicals are formed, which combine in N 2 to C 2 F 6 (reaction (7)), or in air add O 2 to form CF 3 O 2 , which in turn reacts with CF 3 O to form CF 3 O 3 CF 3 (reactions (1) and (8)) [14,29]. Both compounds C 2 F 6 and CF 3 O 3 CF 3 could not be detected in these experiments.…”

The dark reactions F2 + CF3I, C2F5I, andn-C3F7I

“…it is expected to be fast. In systems rich in 0 2 , it appears that CF3O2 and CF30 combine to form the trioxide CF30 + CF3 -CF20 + CF4 [19,20]:…”

Thermal decomposition of trifluoromethoxycarbonyl peroxy nitrate, CF3OC(O)O2NO2

“…This is a consequence of the high NO x concentrations present in the system. These reactions could become important in systems with very low or zero NO x concentrations as Nielsen et al reported [14] when they observed the formation of a trioxide in their system. Biggs et al [22] considered secondary chemistry reactions since their concentrations of CF 3 O x and NO radicals differ by less than an order of magnitude.…”

“…The observed products can be quantitatively accounted for by a sequence of reactions following formation of the CF 3 OC(O)O 2 radical as summarized in Table I [14]. The reaction leading to the unimolecular decarboxylation of CF 3 OCOO:…”