Interatomic Auger transitions in ionic compounds

Interatomic Auger transitions associated with valence electrons from nearest-neighbor atoms to the initial hole-state site have been measured in the ionic compounds NaF, Mg${\mathrm{F}}_2$, and ${\mathrm{Al}}_2$ ${\mathrm{O}}_3$. Both low-(< 100 eV) and high-(> 1000 eV) energy interatomic transitions were observed, corresponding to decay of shallow and deep core hole states, respectively. Of the former group, transitions were identified in which the final states are characterized either by a single vacancy on a site adjacent to the initial hole-state site (interatomic Coster-Kroning decay), by double vacancies localized on an adjacent site, or by double vacancies delocalized on different adjacent sites. A simple model for calculating the energies of these transitions is presented in which corrections assuming complete ionicity and dielectric response are added to empirically determined one-electron binding energies. The corrections take into account the additional electronic polarization and hole-hole interaction energies absent in single-vacancy final states. Electron binding energies measured by x-ray photoemission were self-consistently referenced to the measured kinetic Auger energies from the ionic compounds. These latter energies were then compared with those calculated using the simple model. For both high- and low-energy interatomic transitions the overall agreement, typically in the range of 1-2 eV, was within the uncertainties of the Auger measurements and comparable to that found in the studies of intraatomic core-level transitions.