Screening Effects in Elastic Electron Scattering

In elastic electron scattering atomic screening is shown to affect the cross section both at very small and at very large angles. However, for energies above approximately 200 keV the large-angle screening effects are small, and the cross section may be written as a product of two factors, one depending on the screening effect only and the other on the spin and relativistic effects only. The cross section thus obtained is shown to be in good agreement with previous exact numerical calculations for all angles and all elements. Approximate expressions for large-angle scattering are obtained.