Relativistic effects on the cross section and circular polarization of x-ray radiation following longitudinally-polarized electron impact excitation of highly charged ions

Abstract

Detailed calculations using a fully relativistic distorted-wave method are carried out for the cross sections of longitudinally polarized electron impact excitation from the ground state to the magnetic sublevels of the 1s2p state of highly charged He-like ions. The relativistic effects on the cross sections and circular polarization of the x-ray photoemission are investigated in detail. For the excitation process, results show that the relativistic effects may become important leading to considerable enhancements in the cross sections. The inclusion of the relativistic effects can modify the cross sections by several orders of magnitude, especially to the Mf = and magnetic sublevels. For the de-excitation process, the relativistic effects make the degree of circular polarization decreases, these features are more pronounced when the incident electron energy and/or atomic number increase. The relativistic effects are found to be much larger compared to the case of the linear polarization of radiation.