Studies Of Low Energy Electron/photon Scattering With Hydrogenlike Ions By Exterior Complex Scaling And R-matrix Methods

Atomic/molecular collision processes are universal physical phenomena in astro-nomical and plasma physics. In recent years, with the development of experimental technology, a lot of experimental data have been measured in astronomical and plasma environments and high accuracy theoretical results are needed urgently to interpret the experimental data. And it's significant to study atomic collisions in astronomical and plasma environments. In this dissertation, photoionization processes of hydrogenlike ions (Li?Be+?B2+) exited universally in astronomical environments have been studied by using R-matrix method, and electron hydrogen atom impact ionization and electron hydrogenlike helium scattering processes have been investigated in Debye plasmas for the first time by employing ECS method. This thesis is organized as follows:The basic backgrounds of atomic collision processes have been summarized in Chapter 1. Since the main works of this thesis are studying atomic collisions in plasma environments, the backgrounds of plasmas have also been summarized. The practical theoretical methods that deal with atomic collision processes have been introduced in the second part of this chapter.In Chapter 2, K-shell photoionization of Li, Be+ and B2+ from ground state 1s22s2Se have been studied by using the R-matrix method with pseudostates. The K-shell photoionization process is featured with the contributions from the core-excited metastable states or dominated by the Auger states 2Po. The resonant parameters of the Auger states 2Po and the photoionization cross sections have been calculated and com-pared with the available experimental and theoretical works. Our results agree very well with that of the published works. It is worth noting that compared with previous theoretical calculations, our results of B2+ show better agreements with the latest high-resolution advanced light source measurements. We also study low energy electron scattering with hydrogen-like ions and calculate resonant parameters of resonances that dominate the collision strengths of the collisions by R-matrix method, and find the res-onant width of the same resonant state becomes larger with the increasing of the nuclear charge Z.In Chapter 3, low energy electron-impact ionization of hydrogen atom in De-bye plasmas has been investigated by employing the exterior complex scaling method.The interactions between the charged particles in the plasma have been represented by Debye-Hiickel potentials. Triple differential cross sections (TDCS) in the coplanar equal-energy-sharing geometry at an incident energy of 15.6 eV for different screening lengths are reported. As the screening strength increases, TDCS change significantly.The evolutions of dominant typical peak structures of the TDCS are studied in detail for different screening lengths and for different coplanar equal-energy-sharing geometries.In Chapter 4, low energy electron elastic scattering and impact ionization with hydrogen-like helium in Debye plasmas have been investigated by employing the ex-terior complex scaling method. The interactions between charged particles in the plas-mas have been represented by Debye-Huckel potentials. The 1s-1s elastic collision strengths below the n = 2 excitation threshold of He+ dominated by resonance struc-tures are calculated for different screening lengths. As the screening strength increases,the resonance peaks studied (2(1, 0)2+ 1Se, 3Po, 1De and 2(0,1)2+Po) exhibit blue shifts,and then red shifts with the further increasing of the screening strength, which result in dramatic changes of the collision strengths. It is found that these dynamic varia-tion features of the resonances are related to the changes of energy levels of He+ in the screened potential and geometric configurations of resonances. Triple differential ionization cross sections (TDCS) in coplanar geometries at the incident electron energy of 6 Ryd for different screening lengths are also reported. It is shown that the TDCS experience significant changes with varying the screening length.Finally, conclusions of this thesis and perspectives of the probable research are given in Chapter 5.