The Rate Constant for the Recombination Reaction Between CF3 and O2 Measured Between 2 and 110 Torr

Abstract

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 .

Time resolved FTIR emission measurements of the internal energies of NO formed in the O(1D) + N2O reaction, and energy transfer processes to N2O

“…The technique of time resolved FTIR using a step scan interferometer has been described in several reviews [15][16][17] and our experimental arrangement 18,19 is summarised here. Radiation at 193 nm from an excimer laser (Lambda Physik Compex 102/110i, 70 mJ pulse À1 , 10 Hz) was multipassed through a reaction vessel equipped with Welsh cell optics.…”

Kinetics and mechanism of the thermal gas‐phase oxidation of perfluorobutene‐2 in presence of trifluoromethyl hypofluorite

“…The study of the equilibrium of R • + O 2 → RO 2 • 42 indicates that at the pressure of O 2 used in our work, the CF 3 O(C 4 F 8 ) • radicals and other perfluoroalkyl radicals generated in this reaction system react rapidly with O 2 . The high pressure limit values of 1.5 × 10 9 and 1.26 × 10 9 dm 3 mol −1 s −1 were reported for the rate constants for the O 2 addition to CF 3 • 43 and CF 3 CFHO • 44, respectively. The rate constants for the reactions of haloalkyl radicals with O 2 exceed those of fluorine atom abstraction from CF 3 OF by several orders of magnitude 23, 24, 25, 46.…”

Infrared emission accompanying the gas phase recombination of alkyl radicalsElectronic supplementary information (ESI) available: Appendix: Model for emission from the C2H6 recombination product of CH3 radicals. See http://www.rsc.org/suppdata/cp/b3/b303780k/

“…The technique of time-resolved FTIR using a step scan interferometer has been described in several reviews, [14][15][16] and our experimental arrangement 17,18 is summarised here. Radiation at 193 nm from an excimer laser (Lambda Physik Compex 102, 100 mJ pulse À1 , 10 Hz) entered a reaction vessel equipped with Welsh cell optics in the infrared, either in a single pass or multipassed with high reflectivity mirrors (see below).…”