Circular polarization of X-ray radiation emitted by longitudinally polarized electron impact excitation: Under a screened Coulomb interaction

Longitudinally polarized electron impact excitation from the ground state 1s 2 to the excited state 1s2l (l =s,p) levels of highly charged He-like Fe24+ ions in weakly coupled hot-dense plasmas is investigated using a fully relativistic distorted-wave method. The Debye-Hückel potential is used to describe the plasma screening. Benchmark results such as the total cross sections, the magnetic sublevels cross sections, and the circular polarizations of corresponding X-ray radiations are presented. For the excitation process, results show that the plasma screening has an effect in reducing both the total and magnetic sublevels cross sections. For the de-excitation process, it is found that while the plasma screening as a slightly effect on the circular polarizations of radiations for the 1 s 2 s 3 S 1 → 1 s 2 1 S 0 , 1 s 2 p 3 P 2 → 1 s 2 1 S 0 , and 1 s 2 p 1 P 1 → 1 s 2 1 S 0 transition lines, it gives a substantial contribution for the same properties of the 1 s 2 p 3 P 1 → 1 s 2 1 S 0 line.