Photoionization and Photoemission by the Standing  Intensity of Dynamical XRay Diffraction.
Abstract
This thesis contains theoretical studies of nonrelativistic, innershell photoionization, and angleresolved, photoelectron ejection by the standingwave intensity of dynamical x ray diffraction in the Bragg reflection geometry. These studies are carried out for two purposes: (1) to put the yield formulae of the XRay Standing Wave Technique (XSWT) in the differential form most appropriate for the application of photoelectron spectroscopy, and (2) to answer a lingering question on the adequacy of the dipole approximation for describing the photoeffect spectra of XSWT via investigating the effects of quadrupole retardation on the determination of the coherent fraction and the coherent position. In the dipole approximation, electron photoejection by the standingwave intensity of XSWT has been found to differ from corresponding fluorescence and Auger emissions in that it proceeds at rate not proportional to the standing wave intensity unless the dynamical diffraction field is in the sigma polarization geometry, or otherwise the XSWT experiment is performed at small Bragg angles or nearnormal incidence conditions. It has also been found that the coherent position is by no means sensitive to effects owing to quadrupole retardation, whereas numerical results calculated for a Si adsorbate on a Ge substrate have exhibited changes exceeding 10% in the magnitude of the coherent fraction, but only for unfavorable experimental conditions. This observation has led to concluding the dipole approximation sound and accurate for most practical XSWT experiments.
 Publication:

Ph.D. Thesis
 Pub Date:
 1992
 Bibcode:
 1992PhDT.......173K
 Keywords:

 Physics: General; Physics: Optics; Physics: Radiation