Indirect x-ray line formation processes in highly charged barium

Abstract

We have studied indirect excitation processes contributing to the x-ray line emission of neonlike barium (${\mathrm{Ba}}^{46+}$) interacting with an electron beam. Techniques are presented which resolve the contributions due to electron capture by fluorinelike ions and inner-shell ionization of sodiumlike ions from contributions due to direct electron-impact excitation and radiative cascades. The strength of resonance excitation of the 2p--3s magnetic quadrupole line through intermediate levels 4lnl' (n=5,6) is measured to equal S=(2.8\ifmmode\pm\else\textpm\fi{}0.8)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}19}$ ${\mathrm{cm}}^{2}$ eV.