Origin of Two-Electron, One-PhotonK—X-Ray Transitions

Hartree-Fock energy and intensity calculations show that the two-electron, one-photon $K^2-L^2$—x-ray transitions recently reported are due to $1s^{-2\mathrm{}}\to 2s^{-1\mathrm{}}2p^{-1\mathrm{}}$ electric dipole transitions. The mechanism which we use to describe the $1s^{-2\mathrm{}}\to 2s^{-1\mathrm{}}2p^{-1\mathrm{}}$ transition is based on a "shake-down" model.