Theoretical Study On Polarization Properties Of Radiative Lines Following K- And L-Shell Electron-Impact Excitation Of Highly Charged Ions

Electron with highly charged ions collision is one of the important means for studying the internal structure and properties of atoms,and the process widely exists in various plasma environments.The spectral lines radiated by highly charged ions contain many meaningful observable physics parameters reflecting plasma information,such as impact-excitation cross sections,rate coefficients and collision strengths etc.Compared with impact parameters,the angle-and polarization-resolved properties of characteristic photons are found to be more sensitive to various（weak）physical effects and interactions,which have significant practical research significance.Based on this,the following work was carried out in detail:1.The effects of the Breit interaction on the linear polarization and angular distribution of the characteristic Lyman-α₁ line(2p_3/2→1s_1/2)following electron impact excitation and subsequent decay of hydrogenlike Ti²¹⁺,Mo⁴¹⁺,Ba⁵⁵⁺,and Au⁷⁸⁺ions have been studied by using the relativistic distorted-wave（RDW）program REIE06.The findings show that the presently obtained linear polarization agree excellently with other theoretical and experimental results within the experimental uncertainties.Moreover,the Breit interaction makes the characteristic line of these ions less linearly polarized and less anisotropically,and such an effect of the Breit interaction becomes more promiment with increasing impact energy and atomic number Z,respectively.For instance,for medium-Z Ba⁵⁵⁺ions,the polarization behavior and angular emission pattern of the characteristic Lyman-α₁ line is qualitatively altered at the impact energy of about 4.2 times the excitation threshold due to the contribution of the Breit interaction.2.The effects of the configuration interaction on the 3C/3D line intensity ratio and the linear polarization of the characteristic 3C(2p_1/2⁵3d_3/2¹P₁→2p^{6 1}S₀)and 3D(2p_3/2⁵3d_5/2³D₁→2p^{6 1}S₀)line following electron impact excitation and subsequent decay of neonlike Te⁴²⁺,I⁴³⁺,Xe⁴⁴⁺,Cs⁴⁵⁺,Ba⁴⁶⁺,and La⁴⁷⁺ions have been studied by using the relativistic distorted-wave（RDW）program REIE06.The findings show that our present calculations show a trend very similar to other theoretical and experimental results.In particular,it is found that the 3C/3D line intensity ratio have an apparent change at Z=54,55,which is caused by strong configuration interaction.Considering the linear polarization of the spectral lines radiated by highly charged ions is very sensitive to various physical effects and interactions（such as Breit interaction,hyperfine interaction and multipole mixing of radiation fields）.Thus,the effects of the configuration interaction on the linear polarization of the characteristic 3C and 3D line radiated by neonlike ions was studied.It is found that the configuration interaction equally makes the linear polarization have an apparent abrupt behavior at Z=55.The angular and polarization properties of the characteristic spectra lines following electron impact excitation and subsequent decay of highly charged ions be used as effective tools not only to study various physical effects and interactions such as the configuration interaction and the Breit interaction,but also to provide important theoretical foundation for the diagnosis of plasma environments.