Relativistic Effects in Electron Scattering by Atoms. I. Elastic Scattering by Mercury

Abstract

Elastic scattering of electrons in the energy range 0-25 eV by mercury atoms is investigated by applying a perturbation method to the (nonrelativistic) Schrodinger equation. Relativistic correction to the potential is treated using two models: a Pauli approximation and a second-order Dirac potential. The nonrelativistic Hartree-Fock wavefunction is used to describe the target in the zeroth order approximation. Electron exchange is found to be important in the collision. The relativistic correction due to mass variation makes a significant contribution, in particular to p-wave scattering which is dominated by a low energy shape resonance. Phase shifts for s-, p-, d-and f-wave scattering are presented. An analytic expression for the momentum transfer cross section for relativistic scattering is obtained. The total cross section, momentum transfer cross section, differential cross section and spin polarization are calculated and compared with experiment.

Elastic Positron Scattering from Krypton and Xenon in the Relativistic Polarized Orbital Approximation

“…First of all it should be noted that while for krypton present relativistic and non-relativistic results almost coincide and both indicate the Ramsauer-Τownsend minimum, for xenon both sets of results differ remarkably at energies below 4 eV and only the non-relativistic data exhibit the minimum. As regards comparison with other theoretical data, an overall agreement between present relativistic results and those of Sin Fai Lam [16] should be stressed. That author used in his scattering calculations the Dirac-Hartree-Fock static potentials together with the scaled dipole polarization potentials obtained in the relativistic Po p l e -S c h o f i e l d (PS) method [25].…”

“…Comparison with available experimental results slows the serious disagreement both for the total elastic and the differential elastic cross-sections. On the theoretical side, our data agree almost excellently with the results obtained by Sin Fai Lam [16] in the relativistic Pople-Schofield approximation but differ seriously from the non-relativistic polarized orbital results of McEachran et al [15]. We argue that although results of the latter group are in the better agreement with experiment, they were obtained in a methodologically questionable way.…”

“…2 and 3 our results of the total elastic cross-sections for Kr and Xe with the calculations of McEachran et al [15] and Sin Fai Lam [16]. Theoretical results of Massey et al [13] and Basu et al [17], for Kr, and Schrader [14], for Kr and Ye, were obtained using semi-empirical potentials and are not shown.…”

“…Theoretically, Massey et a1. [13], Schrader [14], McEachran et al [15], Sin Fai Lam [16] and Basu et a1. [17] investigated the low-energy total elastic cross-section.…”

“…On the theoretical side, calculations of the total elastic scattering include those of Schrader [14], McEachran et al [15] and Sin Fai Lam [16]. The differential cross-sections for elastic scattering at intermediate energies were reported by Hasenburg et al [24].…”