Electron capture into metastable Kr⁸⁺ recoil ions

Abstract

Energy and time distributions of Auger electrons from highly ionized krypton have been measured after impact on a krypton gas of a pulsed 0.7-MeV/amu Cl¹¹⁺ beam. The energy spectrum, measured delayed relative to the beam, exhibits MNn Auger electron lines following electron capture into metastable 3d⁻¹4s excitations of Kr ⁸⁺ recoil ions, with smaller contributions from Kr⁹⁺ and Kr¹⁰⁺. The distribution of primary-capture orbits in the n=6 and n=7 shells is changed with the ionization potential of the donor gas, observed in gasmixture experiments. Theoretical calculations of lifetimes and Auger electron energies are made. The classical model for electron capture explains both the mean-excitation state and the qualitative variation of the found total capture cross sections.