Many-electron effects in Lγ2,3x-ray emission spectroscopy spectrum of BaO

The L${\gamma }_2$,3 (2$s^{\mathrm{-}1}$→4$p^{\mathrm{-}1}$) x-ray emission spectrum of BaO was measured in fluorescence with a high-resolution vacuum double-crystal spectrometer. The spectrum was also calculated by the Green’s function method. It is shown that the spectrum can be interpreted essentially in terms of a two-level system in the final state, e.g., the 4p hole level interacting with the product of the 4$p^{\mathrm{-}1}$⇆4$d^{\mathrm{-}2}$4f super Coster-Kronig process. It is also shown that it is necessary to take into account the 4$d^{\mathrm{-}2}$4f multiplet.