Crossed-Beam Study of the Reactive Asymmetry of Oriented Methyl Iodide Molecules with Rubidium

Abstract

A crossed molecular‐beam study of the reactive asymmetry of oriented methyl iodide molecules reacting with rubidium is described. The velocity‐selected molecular beam of CH₃I is focused by an inhomogeneous electric six‐pole field; the CH₃I molecules are then oriented with respect to the incoming atomic beam of Rb by means of a homogeneous, weak, electric field. Measurements of the intensity of the RbI product have been made at various laboratory scattering angles as a function of the relative alignment of the CH₃I with respect to the incident relative velocity vector. A computer analysis of the data has shown that the differential reactive scattering cross section (in the backward center‐of‐mass direction) for the “favorable” CH₃I alignment exceeds that for the “unfavorable” alignment by a factor of 4 or more. A simple hardsphere model, approximating methyl iodide as a partially reactive sphere, accounts for many of the important features of the observations.