Absolute rate of the reaction of Cl(2<i>P</i>) with methane from 200–500 K

Abstract

Rate constants for the reaction of atomic chlorine with methane have been measured from 200–500 K using the flash photolysis–resonance fluorescence technique. When the results from 14 equally spaced experimental determinations are plotted in Arrhenius form a definite curvature is noted. The results are best represented by a statistically evaluated least squares three-parameter fit given by k=5.44×10−19 T2.50 exp(−608/T) cm3 molecule−1 s−1. Over the range 299–500 K, the data are well represented by the Arrhenius expression k= (18.4±2.8) ×10−12 exp(−1545±52/T) cm3 molecule−1 s−1, while the corresponding expression for the 200–299 K range is k= (6.51±0.79) ×10−12 exp(−1229±27/T) cm3 molecule−1 s−1. The error limits are the standard deviations of the least squares fit.. The results are compared to previous work and are theoretically discussed.