CROSS SECTIONS AND RATE CONSTANTS FOR ION-MOLECULE REACTIONS

The importance of ion-neutral reactions is well recognized, especially in the study of the chemistry of upper atmosphere. The first section of the report is concerned with refining the calculation of the cross section from the long-range interactions, assuming an arbitrary classical potential. The cross section so found is not regarded as an approximation to the reaction cross section, but rather the cross section for any sort of significant interaction, that is, the sum of the cross sections for elastic scattering, inelastic scattering, and the various reactions that can occur. The next section is a rigorous analysis of the experiments, based on the kinetic theory of gases, from the point of view of expressing whatever macroscopic parameters the experiment yields in terms of the reaction cross section, which is assumed known as a function of energy. An approximate method is developed which inverts the relationship and yields the reaction cross section as a function of energy if the experimental data are adequate. The final section applied the above-mentioned method to various reactions. This is believed to be the only way to find the cross section as such for ion-neutral reactions in the energy range somewhat above thermal. Some new and unexpected results were found by this method, especially for the H2, Ne reaction. (Author)