The kinetic isotope effect in the reaction of O(3<i>P</i>) with H2, D2, and HD

Abstract

The reaction of O(3P)+H2, D2, and HD was studied by the flash photolysis-resonance fluorescence method. The rate constants kXY(T) were measured over the temperature ranges 297–471 K for XY=H2, 422–472 K for D2, and 422–473 K for HD. Above 400 K kH2 are in excellent agreement with earlier flow measurements, but below this temperature most of the flow data are systematically lower. A small deviation from the Arrhenius function was observed for kH2 at 297 K. Our measurements of kD2 are in excellent agreement with the results of Westenberg and deHaas and differ from those Clyne and Thrush. The measured values of kHD equal the arithmetic mean of kH2 and kD2 within experimental error. A detailed comparison is made between the present results and the CEQB calculations of Bowman, Wagner, Walch, and Dunning and the ICVT/LAG calculations of Garrett and Truhlar. Good overall agreement is obtained with both theories.