Energy and Angular Distributions of Electrons from Atoms and Molecules by Electron Impact

Abstract

Some experimental results on cross sections, differential in energy and angle, for electrons scattered or ejected from helium, methane, carbon monoxide, and water by intermediate-energy electron impact are presented, and the doubly differential cross section for helium is compared with theoretical calculations for models such as the scaled Born approximations with and without interference, the plane-wave Born approximation, the Born approximation with the Roothaan ground state wave function, and the binary encounter theory, resulting in a fairly good agreement between experiment and theory for the Born approximations except in the case of the plane-wave Born approximation. The experimental doubly differential cross sections are integrated over angles to derive the singly differential cross sections, differential only in energy, which are compared with the Mott cross sections corrected for binding energies of orbital electrons. Finally, the bearings of the measurement of doubly differential cross sections on the description of the track structure, the electron slowing-down spectra, the total ionization cross sections, and the stopping power for lower energy electrons are discussed. (auth)