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 3 2 = J (2) 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 M f = −1 and −2 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.

Relativistic effects on the linear polarization and angular distribution of x-ray radiation emitted by inner-shell photoionization of atoms

“…It is evident that the polarization rapidly decreases as the atomic number increases in the nonrelativistic treatment; while due to the relativistic effect, there is only a weak dependence on the atomic number, at four times the ionization energy. All these features are found to be very different compared to the case of the circular/linear polarization of radiation emitted by longitudinally polarized/ unpolarized electron impact excitation process [4,5], where the polarization of the resulting radiation is independent of atomic number in the nonrelativistic limit. However, when the effects of relativity are taken into account, the polarization becomes markedly Z-dependent.…”

“…ionization followed by the radiative de-excitation filling of an inner-shell vacancy induced by the impact of a photon, has practical implications in both astrophysical and laboratory plasmas. When compared to conventional observables, such polarization helps to reveal many details regarding the magnetic sublevel population [1][2][3][4][5], and, in fact, provides new insight for studying the electron-photon (e-ph) interaction during the dynamical process [6,7].…”

Polarization transfer in x-ray transitions due to photoionization in highly charged copper-like ions

“…On the other hand, such aligned target ions will be manifested in the polarization and the non-isotropic angular distribution of the characteristic x-rays [2]. From analysis of the polarization [3][4][5][6], valuable information can be obtained for a detailed diagnosis of the plasma state and analysis of the complex spectra formation.…”

Dominance of the radiative cascades in the cross section and circular polarization of x-ray radiation

“…Dipti et al [14] reported a series of results for the polarization for tungsten ions using the fully relativistic distorted-wave (RDW) method. There are also many other publications on the polarization of the emitted x-ray radiation [15][16][17][18][19][20][21][22][23][24][25].…”

“…However, due to the formidable experimental difficulties, quantitative information about circular polarization is still limited and far from satisfies the needs of practical applications. A systematic calculation of the circular polarization properties of the characteristic x-rays was attempted by Inal et al [15][16][17], and also, more recently, by us [19,20]. In these studies, some higher-order physical effects such as BI and relativistic effects during the direct impact process were reported.…”