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Title: Relaxation, polarization, and other many-body effects in the photoionization of atoms

Miscellaneous ·
OSTI ID:5180108

Inner-shell photoionization of lithium, xenon, and barium is investigated using the many-body perturbation theory (MBPT) and a variant of the relativistic random-phase approximation (RRPA) which includes relaxation effects. Particular attention is given to the higher-order effects of relaxation and polarization of the ionic cores that remain following the ionization. Other notable effects such as interchannel coupling, photoionization with excitation and relativistic effects are also examined. For lithium the author has used MBPT to calculate the total cross section over a wide range of photon energies including spectral regions containing single- and double-electron autoionizing resonances. Partial photoionization cross sections have also been obtained. The results are compared with recent experiments. The photoionization cross sections and angular distribution asymmetry parameters of the 4d{sup 10} and other single-excitation channels of xenon and barium have been calculated using various many-body techniques. Relaxation effects have been included by evaluating many-body diagrams and also by calculating excited orbitals in the field of the relaxed ionic core. In the latter case, overlap integrals between initial and final-state orbitals of the spectator electrons were included. Polarization effects have been included by the evaluation of appropriate many-body diagrams. A modified form of the RRPA which includes relaxation effects by calculating excited orbitals in the field of the relaxed ionic core has been used to investigate relaxation effects in the photoionization of the 4d{sup 10} subshells of xenon and barium as well as the 3d{sup 10} subshell of xenon. In addition, the frequency-dependent polarizabilities of Cl and Cl{sup {minus}} were calculated to determine the extent to which second-order Stark shifts contribute to the photo detachment threshold shift observed when Cl{sup {minus}} is placed in an intense laser field.

Research Organization:
Virginia Univ., Charlottesville, VA (United States)
OSTI ID:
5180108
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English