Electron-spectroscopy study of inner-shell photoexcitation and ionization of Xe

Electron spectroscopy, combined with synchrotron radiation in the photon-energy range hν60-190 eV, was used to measure the angular distributions of Xe $5p$ and $5s$ photoelectrons and of N4,5OO Auger electrons. The branching ratios and partial cross sections for photoionization and Auger processes were also measured in certain cases. The measured asymmetry parameter β for $5p$ photoelectrons agrees well with many-electron calculations, which predict a pronounced oscillation in β₅ₚ above the $4d$ ionization threshold due to the 4d-5p intershell interaction. The N4,5OO Auger electrons are produced with photon-energy-dependent anisotropic angular distributions, resulting from alignmentof Xe⁺ by photoionization. The theoretical analysis of Auger-electron angular distributions is described, and theoretical calculations are found to predict the measured asymmetries well. In addition, Auger-electron peaks were observed to broaden and shift at photon energies near the $4d$ ionization threshold because of postcollision interaction. The measured shifts of the N₅O₁O₁ ¹S₀ line agree with previous measurements and theory. Electron spectra recorded through the energy region of the 4d→np Rydberg states show that they decay primarily by the Auger process, while the $5p$ and $5s$ partial cross sections are relatively weakly affected by autoionization. However, distinct resonance structure was observed in the β parameters for 5p3/2 and 5p1/2 photoelectrons. The measured results are compared with a theoretical calculation of resonant photoionization for the 4d→6p excitation.