Statistical Theory of Fourhyphen;Body Bimolecular Resonant Ionndash;Molecule Reactions

摘要

A fourhyphen;body phase space theory of ionndash;molecule reactions of the type A2plus;thinsp;plus;thinsp;A2thinsp;lrarr2;thinsp;(A4plus;)thinsp;rarr;thinsp;A3plus;thinsp;plus;thinsp;A is presented. A modified definition of strong coupling is introduced by including the asymptotic resonance or chemical bonding potential in the reactant channel. It is shown that: (a) this leads to a larger cross section for the backward reaction than would be predicted using only the ionndash;induced dipole (polarization) potential, and (b) leads to cross sections for both the forward and backward reactions using hydrogen which are in better agreement with experiment than previously predicted. A computer program has also been developed following Nikitin's presentation of the fourhyphen;body phasehyphen;space theory. Cross sections are presented as functions of the barycentric kinetic energyEin the range0.01thinsp;le;thinsp;Ethinsp;le;thinsp;10eV, and comparison is made between the statistical theories using the resonance potential and the polarization potential. Calculations with vibrationally excited reactants were also performed. Inclusion of the resonance potential shows a larger dependence of the cross section in the forward direction on the reactant vibrational energy than is predicted using the inducedhyphen;dipole potential only. These results also tend to give better agreement with existing experiments and yield predictions that may be tested by future experimentation.