Multielectron coincidence study of the double Auger decay of3d-ionized krypton

Multielectron coincidence data for triple ionization of krypton have been recorded above the 3$d$ ionization threshold at two photon energies (140 and 150 eV). Three principal transition pathways have been observed, two involving double Auger transitions from ${\mathrm{Kr}}^{+}$, and one involving single Auger transitions from ${\mathrm{Kr}}^{2+}$ created by direct single-photon double ionization. The decay of the $3d^9$ ${}^2$ $D_{5/2,3/2}$ states in ${\mathrm{Kr}}^{+}$ has been analyzed in some detail and is found to be strongly dominated by cascade processes where two electrons with well-defined energies are emitted. The decay paths leading to the $4s^2$ $4p^3$ ${}^{4}S$, ${}^{2}D$, and ${}^{2}P$ states of ${\mathrm{Kr}}^{3+}$ are analyzed and energies of seven intermediate states in ${\mathrm{Kr}}^{2+}$ are given. A preliminary investigation of the decay paths from ${\mathrm{Kr}}^{+}$ $3d^9$ $4p^5\mathit{nl}$ shake-up states has also been carried out.