Wide Temperature Range Kinetics of the O + CHF3 Reaction

Rate coefficients for the depletion of ground-state oxygen atoms by CHF3 have been measured using a high-temperature photochemistry (HTP) reactor. The O atoms were generated by the vacuum ultraviolet (VUV) flash photolysis of either SO2, O2, or CO2, and their relative concentrations were monitored by resonance fluorescence. The data are best fitted by the expression k(630−940 K) = 2.5 × 10-11 exp(−7236 K/T) cm3 molecule-1 s-1. The data are contiguous with those from an earlier laser-photolysis shock-tube study for temperatures ranging from 960 to 1330 K. A fit to the combined data yields the recommendation k(630−1330 K) = 5.1 × 10-10 exp(−9536 K/T) cm3 molecule-1 s-1, with 2σ precision levels varying from ±8 and ±22% and corresponding suggested accuracy levels of ±22 to ±29%. Transition-state theory predictions, made using input data from a literature ab initio study, are in excellent agreement with this recommendation over the entire temperature domain.