Autoionization of the Ca 2p53d core resonances: Breakdown of the spectator model

The decay of the photon-excited 2$p^5$3$s^2$3$p^6$3d4$s^2$ core resonances of atomic Ca has been studied by electron spectroscopy and by multiconfiguration calculations of the autoionization rates. Strong correlation effects give rise to complicated line structures that are mostly due to the autoionization of the resonances into the 3$p^4$3d4$s^2$εl, 3$p^4$3d4$p^2$εl, and 3$p^4$3$d^3$εl continua. The breakdown of the spectator model, which is caused by the collapse of the 3d orbital, manifests itself in the dramatic differences between the spectra excited via the two resonances split by the spin-orbit and 2p-3d interactions.