Double differential cross sections for alkali–Hg collisions in the 100 eV range. I. Time-of-flight measurements

Abstract

Differential cross sections with energy analysis have been measured for Na, K, and Cs atoms scattered from Hg for collision energies between 36 and 200 eV. The energy analysis is performed with standard time-of-flight technique yielding the cross sections for elastic scattering and scattering with excitation of the lowest alkali P state. The cross sections for all other excited states are found to be smaller by several orders of magnitude. A new semiempirical potential model is described which has been used to interpret the experimental results. Parameters for the best fit to our results are given in this two-state model for K and Cs. For Na we can only give a coarse estimate. Some serious failures of the semiclassical theory have been discovered, which have lead us to the use of quantum mechanical calculations.