Kinetics of the Cl–H2 system. III. The deuterium isotope effect in Cl+H2

The rate constant for the reaction Cl+D2 was measured over the temperature range 200–500 K, using the flash photolysis-resonance fluorescence technique. These data, together with previous measurements for Cl+H2, are compared with the isotope effect measured by Persky and Klein in a static bulb. Over the range 295–500 K, our data are in excellent agreement with their results. At lower temperatures, the Cl+D2 rate constant displays an anomalous non-Arrhenius curvature. A mechanism involving the reaction of Cl atoms with vibrationally excited D2 is proposed to explain this effect.