Theoretical Studies On Photoionization Cross Sections Of Atoms And Molecules In Real System

A dielectric influence function (DIF) and new expression for photoionization cross-sections are suggested to study the photoionization cross-sections of atoms and molecules in real system. The basic picture is that the photoionization cross-sections of atoms in a real system can be described as the coupling between quantum quantity (QQ) and classical quantity (CQ) parts. The QQ part represents the photoionization cross-sections of an isolated atom, while the CQ part (the DIF) may represent most of the important influence of the macroscopic effects, e.g., the interactions among the photoionized atom and all surrounding particles, and the dielectric property of the system, on the photoionization cross-sections.In Chapter 1 we give the main goals of this dissertation and the basic experimental principles of photoionization process. Chapter 2 reviews some important developments of theoretical and experimental photoionization studies. Chapter 3 describes the photoionization cross-sections of isolated atoms. In Chapters 4 and 5 we suggest a dielectric influence function and new expressions of photoionization cross-sections for high-density photoionization system using the experimental Beer-Lambert's law and Maxwell's equations. Chapter 6 presents some quantitative methods used to obtain the real part of polarizability, which is necessary to calculate the DIF and the photoionization cross-sections. Chapter 7 shows some photoionization cross-sections of solid Xe, Ba, Au and Ag using our new method, and shows good agreement between present results and experimental cross-sections. Conclusions and suggestions are given in Chapter 8.