(e, 2e) collisions on xenon with spin-polarized electrons

Abstract

We present measurements of the (e, 2e) cross sections of xenon for transitions leading to the 5p 3/2 and 5p 1/2 states of the residual ion using an incident polarized electron beam in coplanar asymmetric kinematics and in the intermediate energy regime. The results show that the spin up-down asymmetry for the 5p 3/2 and 5p 1/2 transitions can be understood as an analogue of the so-called fine-structure effect in inelastic scattering. However, our present measurements also point to significant contributions from relativistic effects in the electron-atom system under certain conditions. The measured spin up-down asymmetry is analysed using the density matrix formalism. This approach reveals that different exchange interactions contribute to the fine-structure effect for ionization. The contribution of relativistic interactions in the observed parameters is also investigated by using a semirelativistic DWBA model to evaluate the scattering amplitudes.

Correlations in Electron - Atom Collisions involving Polarised Electrons and Photons

“…However, neither the use of relativistic target orbitals Granitza et al . 1996), nor the inclusion of continuum spin-orbit interactions (Dorn et al . 1997), provided a significant improvement in the agreement between experiment and theory.…”

“…So far the investigations for spin-resolved (e, 2e) studies in Xe have concentrated on 147 eV electrons Granitza et al . 1996;Dorn et al . 1997).…”

“…Significant spin asymmetries are observed at this energy and first calculations Granitza et al . 1996;Dorn et al . 1997) were in qualitative agreement with the observations.…”

Interference and Spin Effects in Relativistic (e, 2e) Collisions

“…It was found that certain algebraic relations between the results for p 1/2 and p 3/2 levels, expected from the formal representation of the argument indicated above, were only qualitatively satisfied. Moreover, the DWBA description of these experiments was found to be only moderately successful (Dorn et al 1997). To explain these observations, it has been argued that many-body effects have a significant influence on these outer shell TDCS and asymmetries .…”

“…The (e, 2e) fine structure effect has been investigated in detail for the case of the 5p levels of xenon (Guo et al 1996;Hanne 1996;Dorn et al 1997;Mette et al 1998). It was found that certain algebraic relations between the results for p 1/2 and p 3/2 levels, expected from the formal representation of the argument indicated above, were only qualitatively satisfied.…”