Anisotropy and polarization of x-ray line emissions in the dielectronic recombination of hydrogenlike Fe25+ ions

Abstract

We present a systematic study of the anisotropy and polarization of x-ray line emissions in $KLL$ dielectronic recombination of hydrogenlike ${\mathrm{Fe}}^{25+}$ ions. For the $KLL$ dielectronic recombination considered, it consists of a resonant electron capture plus a two-step radiative decay. While the anisotropy and polarization of the first-step decay photons are calculated by using the flexible atomic code, those of the second-step decay photons are obtained with two methods, i.e., the formalism of the deorientation factor and density matrix theory. Resonance strengths are presented as well to synthesize the dielectronic satellite line spectra. The synthetic spectra including the correction of anisotropy and polarization effects show better agreement with existing experiments than previous calculations. This indicates that these effects are important for the intensity distribution of the dielectronic satellite lines.