Photoionization and electron-impact ionization ofKr5+

Abstract

Absolute photoionization cross sections for ${\mathrm{Kr}}^{5+}$ were measured in the photon energy range $74\char21{}175\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ using synchrotron radiation. For comparison, a detailed energy scan of the electron-impact ionization cross section was made in the same energy range and normalized to previously published absolute measurements. The Flexible Atomic Code and Cowan atomic structure code were used to calculate energy levels, excitation energies, and oscillator strengths for $3d\ensuremath{\rightarrow}np$, $3\mathrm{d}\ensuremath{\rightarrow}nf$, and $4s\ensuremath{\rightarrow}np$ autoionizing transitions from the ground and metastable states. Within the experimental uncertainty, oscillator strengths determined from the photoionization measurements are in agreement with both calculations. Excitation-autoionization and resonant excitation-double-autoionization features are evident in the electron-impact ionization cross section.