Experimental and theoretical shake-up studies. The rare gases

The x-ray photoelectron shake-up spectra on the Ar $2p$ and Kr $3d$ core levels have been obtained to high statistics. The shake-up energies and intensities on the Ne $1s$, Ar $2p$, Kr $3d$, and Xe $3d$ levels have been calculated using Hartree-Fock-Slater Xα calculations. These calculations generally show good agreement with experiment and confirm the assignments. The shake-up energies are in good agreement with the optical-transition energies for the equivalent core alkali-metal ions. The relaxation energies from shake-up have been calculated from the experimental spectra, and are shown to be much smaller than the relaxation energies from shake-off.