Quasiclassical trajectory study of the molecular beam kinetics of the deuterium atom–hydrogen halide exchange reactions

Abstract

Unadjusted quasiclassical trajectory computations have been carried out to simulate the molecular beam scattering of thermal D atom beams at 2800 °K crossed with beams of HCl and HI at 250 °K. Total reaction cross sections, energy partitioning distributions, and differential scattering cross sections have been computed for the exchange reactions D+HCl → DCl+H and D+HI → DI+H while total reaction cross sections are reported for the corresponding abstractions, i.e., D+HCl → HD+Cl and D+HI → HD+I. For the exchange reactions, the computed reaction cross sections are within the range estimated from the crossed beam experiments. The calculated average energy partitioned into relative translational motion of products is in near quantitative agreement with the beam results, and the predicted differential scattering cross sections appear to be in qualitative accord with the beam experiments. The over-all agreement between theory and experiment indicates that previously computed values for the thermal rate coefficients for the exchange reactions are of the right order and that a systematic error exists in the interpretation of photolysis data in the hydrogen–hydrogen halide systems.