Relativistic R-matrix Study On The Photoionization Process Of Highly Charged Ions

Photoionization （PI） process is a truly fundamental process of the interaction of light andatomics or ions, and includes direct PI process and resonant PI process. The investigation ofPI is very important for the plasma physics，atomic theory and astrophysics. The PI crosssections of atomics or ions are essential for theoretical modeling of plasmas in both thelaboratory and astrophysical source. In astrophysics, PI of highly charged ions （HCIs） hasbeen recently observed in high-resolution x-ray spectra of quasars, and abundant informationof the universe can be obtained by analyzing the spectrum. In addition, investigations of PIprocess of HCIs have been utilized to study the electron correlations, relativistic effects,quantum electrodynamics （QED） contributions and nuclear size effects and so on. In thisthesis, the PI process are studied systematically by using the software package Dirac AtomicR-matrix Code （DARC） which is based on the fully relativistic R-matrix method andGRASP92based on the multi-configuration Dirac-Fock method. The details are as follows:1. Photoionization （PI） cross sections of the ground state1s²2s²2p⁶¹S₀of Ne-like Ar⁸⁺,Fe¹⁶⁺, Kr²⁶⁺, and Xe⁴⁴⁺ions are calculated by using the Dirac Atomic R-matrix Code （DARC）based on a fully relativistic R-matrix method. To analyze the detailed resonant structure,systematical calculations based on the multiconfiguration Dirac-Fock method （MCDF） areperformed for the dominant2sâ†'np resonant transitions, and the resonant energies, strengths,and total natural widths are presented. The resonant structures and characteristics of the PIcross sections and resonance strengths along the Ne-like sequence are discussed withemphasis on the influence of relativistic effects. For the Ar⁸⁺ion, good agreement is foundbetween the present results and available theoretical calculations and experimental data.2. The detailed PI cross sections of the ground state3s²3p⁶3d²D_3/2and the excited state3s²3p⁶3d²D_5/2of Fe⁷⁺in the3p resonant region and2p-3d resonant region have beencalculated systematically by using fully relativistic Dirac R-matrix method. The PI crosssections of the metastable state3s²3p⁶4s²S_1/2have also been calculated in the3p region.Compared with the available theoretical calculations the present results replication betteragreement with the experiment results by Gharaibeh et.al. In the2p-3d resonant region ourresults also show a good agreement with the theoretical calculations by Zeng et.al.