Superelastic scattering of electrons from highly charged ions with inner shell vacancies.

We report the measurement of electrons scattered superelastically from highly charged ions having an initial K-shell vacancy. In this process, the scattered electron gains approximately 725 eV of energy from the deexcitation of an excited He-like F7+(1s2s 3S) metastable ion to its ground state. Theoretical calculations based on an R-matrix approach agree well in position, shape, and magnitude with the experimental data.