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THEORY OF PHOTOIONIZATION OF OPEN-SHELL ATOMS
Abstract
This dissertation comprises four investigations concerning the photoionization of open-shell atoms. The first two are concerned with anisotropic interaction effects on the photoelectron angular distribution of open-shell atoms within the Hartree-Fock approximation. Calculations are carried out for the outer p-subshells of the halogen (F, Cl, Br, and I) and chalcogen (O, S, Se, and Te) atoms as well as for the 3s-subshell of atomic Al. Large anisotropic interaction (i.e., LS-term-dependent) effects are found for the photoelectron asymmetry parameter (beta) in all cases except for the light elements F and O. Comparison is made to central potential model calculations. The second two investigations are concerned with the development and application of a many-body treatment of open-shell atom photoionization processes using a transition matrix approach. The aim of this investigation is to treat all particle-hole-type interactions so that theoretical photoionization cross sections for open-shell atoms can be calculated with the same accuracy as are random-phase approximation (RPA) results for closed-shell atoms. A graphical procedure is developed to evaluate each term in the equation satisfied by the first-order transition matrix. For those terms involving the interaction of excited virtual pairs of electrons with the ionic core, the interaction is approximated by allowing no exchange of orbital or spin angular momentum with the ionic core. This approximation leads to the RPA in the closed-shell atom case; it is used to define the RPA here for open-shell atoms. This new open-shell transition matrix approach is applied to the calculation of the photoionization cross section of atomic chlorine. Comparison is made to the results of other theoretical approaches.
Subject Area
Atoms & subatomic particles
Recommended Citation
SHAHABI, SIAMAK, "THEORY OF PHOTOIONIZATION OF OPEN-SHELL ATOMS" (1983). ETD collection for University of Nebraska-Lincoln. AAI8328194.
https://digitalcommons.unl.edu/dissertations/AAI8328194