Comparison of the cross sections for reaction of methyl iodide with potassium and rubidium

The ratio of the cross sections σR for the reactions of CH3I with K and Rb has been determined over the range of translational energies Etr up to 1.7 eV. The existence of a threshold energy, an Arrhenius-like positive energy dependence of σR just above threshold, and a postmaximum decline of σR to a minimum with increasing Etr are characteristic features of these reaction systems. Combining the present experimental results with those previously published, it has been possible to construct best overall smooth curves of σR(Etr) for each of the two reactions, suitable for comparison with theoretical calculations.