The rate constant k1 for the recombination reaction between CF3 radicals and O2 has been measured at 295 K over the pressure range of 2-110 Torr, predominately in N2. CF3 radicals were formed by the uv photolysis of CF3I, and their kinetic decay monitored in the presence of NO2 and O2 by observing the infrared emission from the products of the CF3+NO2 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 k1(x) = (2.55±0.11) · 10-12 cm3 molecule-1 s-1 and the low pressure third body recombination rate constant k1(0) = (2.5±0.3) · 10-29 cm6 molecule-2 s-1 with 2σ quoted errors, and the Troe broadening parameter Fc = 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 CF3+Cl2 reaction to (2.3±0.6) · 10-14 cm3 molecule-1 s-1. © by Oldenbourg Wissenschaftsverlag, München.
