Dynamics of bimolecular association reactions

Abstract

An approximate semiclassical trajectory method has been used to calculate capture rates for ion–dipole and dipole–dipole reactions at temperatures between 10 and 400 K. Agreement with experimental data and with other theories is excellent for the reactions of H⁺₃ with HCl and HCN and fair for the reaction ClO with NO. A formal expression for the rate constant for intramolecular vibrational relaxation (IVR) has been derived, and an approximate form of this expression has been used, together with trajectory calculations of capture rates, to model the formation of metastable complexes in the reactions of NH⁺₄ with NH₃ and of NH with NO₂ and NO. The results suggest that the rate of stabilization of the initial collision complex by IVR may have a significant influence on both the absolute value of the overall rate constant and its temperature dependence.