Kinetics of the Cl(2PJ) + C2H6 reaction between 177 and 353 K

Absolute rate data for the Cl + C2H6 --> HCl + C2H5 reaction have been measured from 177 to 353 K using a conventional discharge flow resonance fluorescence technique with helium as the diluent at a pressure of 1 Torr. The rate coefficient at 296 K was measured to be (5.70 +/- 0.13) x 10(-11) cm(3) molecule(-1) s(-1). The Arrhenius expression which describes the temperature dependence of the rate coefficient is (7.32 +/- 0.39) x 10(-11) exp[(-73.6 +/- 12.9)/7] cm(3) molecule(-1) s(-1). The cited errors are at the level of two standard deviations. The results were checked for potential interferences from nonequilibration of atomic Cl spin states, impurities in the Cl atom source, and other secondary chemistry resulting from high reactant concentrations. There was no observed change in the rate coefficient upon the addition of a large concentration of efficient spin quencher, CF4. The results were also found to be invariant to purification of the Cl atom precursor. Numerical simulations confirmed that at the low reactant concentrations used, secondary reactions did not affect the observed rate coefficients to a significant extent.