Coulomb correlations in electron and positron impact ionization of hydrogen at intermediate and higher energies

Abstract

Investigating the relation between the asymptotic condition and the dynamic Coulomb correlation for single and multiple ionization the authors discuss a complete set of spatially separable N-electron final-state wavefunctions, satisfying multiple ionization boundary conditions. They apply these results to electron and positron impact ionization of atomic hydrogen in the energy range 54.4 and 250 eV on the basis of a parameter-free model formulated within the scope of the multiple scattering approach. A comparison between their results and available experimental data and alternative theoretical calculations are made and discussed. The role of exchange is also investigated. The contribution of exchange in the triple differential cross section is found to be virtually negligible whereas the asymmetry parameter A is significantly affected.

Double ionization of helium by a single photon with energy 89–140 eV

“…(8) is written as an integral over position space, and the volume integral is converted to a surface integral, the main contribution comes from the point of stationary phase of the integrand, which corresponds to the classical asymptotic motion of the electrons. Thus, following Rudge and Seaton [6] and Jetzke and Faisal [7], we introduce a quasiclassical wave function that describes the electrons moving asymptotically in the Coulomb potential -(ZI/rI) -(Z2/r2) where Zi and Z2 are velocity-dependent efFective charges given by Z, = Z -4,, i = 1, 2 with Z = 2 and (k; k;~) k; (10) k, --where k;~. = k, -k~.…”

“…I. We therefore choose the trial wave function [6,7] where rq2 --irI -rz]. We note that Pan and Starace [8] recently made use of the same velocity-dependent efFective charges in their study of (e, 2e) collisions.…”

Double ionization of helium by bare ions: Theoretical study of the fully differential cross sections

“…The first model considers the dynamical correlation between the electrons and the target nucleus, assuming the effective charges proposed by Berakdar [33]. The second model additionally incorporates the influence of the receding projectile following the proposal of Jetzke and Faisal [25]. Basically, the field of the receding projectile alters the way in which the emitted electrons interact with the recoiling target nucleus.…”

“…A simpler alternative that we explore in this work, still preserving the Götz and Briggs strategy, is the introduction of the Jetzke-Faisal first-order multiple scattering model [25]. In the ion-atom context its implementation results in the nuclearnuclear interaction being explicitly included in the final state through a Coulomb wave function:…”

“…First, we consider the projectile as a plane wave in both initial and final channels and compare the FDCSs obtained by using two variational initial wave functions of different accuracy together with analytical wave functions proposed for the three-body continuum. Second, we explore the projectile charge sign and magnitude dependence at the fully differential level by introducing a model based on effective charges similar to that introduced by Jetzke and Faisal in their electron and positron atom studies [25]. The usual contour plots that have become familiar in these sorts of studies are presented together with selected cuts in order to help visualize the main physical trends.…”