Spectroscopic, kinetic and mechanistic study of fluoromethylperoxo radicals in the gas phase at 298 K

Abstract

The ultraviolet absorption spectrum of CH2FOZ radicals and the kinetics and mechanism of their self-reaction have been studied in the gas phase at 298 K. Two techniques have been used: pulse radiolysis UV absorption to measure the spectrum and kinetics and long path length Fourier transform infrared spectroscopy (FTIR) to identify and quantify the reaction products.Absorption cross sections were quantified over the wavelength range 220-300 nm. The measured cross section near the absorption maximum is ~~~~~( 2 4 0 nm) = (4.1 1 f 0.67) X cm2 molecule:' Errors are statistical ( 2 4 plus our estimate of potential systematic uncertainty (10%). This absorption cross section was then used to derive the observed self-reaction rate constant for reaction 1, defined as -d[CH2F02]/dt = 2kob[CH2F02]2, CH2F02 + CHZFO2 -products (1). klob = (4.01 f 0.52) X (errors are 2 4 . The only carbon-containing products observed by FTIR spectroscopy were HC(0)F and CH2FOOH, indicating that the majority (>77%) of the self-reaction proceeds via the channel CH2F02 + CH2F02 -CH2F0 + CH2F0 + Oz (la). As part of this work, a rate constant of (3.24 f 0.51) X cm3 molecule-I s-' was measured for the reaction of C1 atoms with CH3F and a lower limit of 1.2 X 10-

Atmospheric Chemistry of HFC-152: UV Absorption Spectrum of CH2FCFHO2 Radicals, Kinetics of the Reaction CH2FCFHO2 + NO .fwdarw. CH2FCHFO + NO2, and Fate of the Alkoxy Radical CH2FCFHO

“…A pulse radiolysis technique was used to measure the UV absorption spectrum of CH2FCFH02 radicals and the kinetics and products of reaction 3. The CH,FCFHO, + NO -CH,FCFHO + NO, (3) atmospheric fate of CHlFCFHO radicals produced in reaction ~~~~~ ~~~~ * Authors to whom correspondence may be addressed.…”

Atmospheric chemistry of dimethyl sulfide: UV spectra and self-reaction kinetics of CH3SCH2 and CH3SCH2O2 radicals and kinetics of the reactions CH3SCH2 + O2 .fwdarw. CH3SCH2O2 and CH3SCH2O2 + NO .fwdarw. CH3SCH2O + NO2

“…The solid line is a linear least squares fit. Transient absorption at 400 nm observed following the pulscd radiolysis (full dose) of a mixture of 0.47 mbar of NO, 5.0 mbar of DMS,10 mbar of 0 2 , and 984 mbar of SF6. The solid line is a first-order rise fit which gives kl" = 3.13 X 10s s-l.…”

Environmental effects of large igneous province magmatism: a Siberian perspective

“…Cl + CH 3 F (HFC-41). The recommended value for k(298 K) is an average of the values from the absolute rate study of Manning and Kurylo [862] and Hitsuda et al [586] and the relative rate studies of Tschuikow-Roux et al [1323], Tuazon et al [1326], and Wallington et al [1398]. The recommended value for E/R is based on the study of [682] and from the relative rate study by Coomber and Whittle [310], which gives a room temperature value a factor of 50 smaller.…”