Energies and lifetimes of excited states in copperlike Kr viii

Abstract

The spectrum of Kr viii has been observed between 180 and 2000 \AA{} by using foil excitation of 2.5-3.5-MeV krypton ions. Twenty new transitions have been classified and eleven new excited-state energies have been determined within the $n=4\ensuremath{-}7$ shells. The ionization potential is derived to be 1015 800\ifmmode\pm\else\textpm\fi{}200 ${\mathrm{cm}}^{\ensuremath{-}1}$. The excited-state energies and fine structures are compared with recent relativistic Hartree-Fock calculations. The $4p$-state lifetime has been measured by performing a simultaneous analysis of decay data for the $4p$ level and for its dominant cascade-repopulating levels. The $4p$ lifetime is found to be 30% shorter than previously measured values and is in excellent agreement with the result of a recent multiconfiguration Hartree-Fock calculation. The source of the discrepancy between this result and earlier measurements is discussed.