Quantum effects in the differential cross Ssctions for the insertion reaction N(2D) + H2

The quantum (QM) scattering theory has been difficult to apply to the family of insertion reactions and the approximate quasiclassical trajectory (QCT) method or statistical calculations were mostly applied. In this Letter, we compare the experimental differential cross sections for the title insertion reaction with the results of QM and QCT calculations on an ab initio potential energy surface. The QM results reproduce well the crossed beam experiment, while a small, but significant, difference in the QCT ones points to quantum effects, possibly the occurrence of tunneling through the combined potential and centrifugal barrier.     

Observed translational energy dependence of the K + C2H5I → KI + C2H5 reaction cross section from 0.17 to 0.55 eV (c.m.)

Relative values of the total reaction cross section σ_R for the crossed molecular beam reaction K + C₂H₅I → KI + C₂H₅ have been measured over the translational energy (E_T) range 0 17–0.55 eV. It is found that σ_R decreases monotonically with E_T over this range, any maximum in σ_R(E_T) is presumed to lie below 0.17 eV.     

Dynamical model for the “translational excitation features” in the atom—diatom reaction cross section

A collision model for the kinetic energy dependence of the reaction cross section has been obtained by considering total angular momentum limitation at the entrance (reactants) or exit (products) reactive channel in the atom—diatom scheme. The model provides a satisfactory representation of the main “translational cross section features” (i.e., Arrhenius like behaviour near threshold, maximum, post-maximum decline and minimum) found in the reaction cross section by molecular beam experiments. Maximum and minimum explanations, including some predictions as well as a comparison with previous theoretical treatments are reported. Also an approximate method to obtain dissociation energies of the product diatom from the cross-section data is presented with relative success.