Screening of 3d holes in the rare earths

The origin of high- and low-energy satellites in rare earth 3d X-ray ohoto- emission spectra are elucidated in terms of the electronic configurations of the final states and related to the screening of the core hole. The role of the two competing mechanisms, change in 4f occupation number and conduction electron screening, is investigated. The 4f levels play a dominant role in strongly insulating compounds. The implications on the study of valence fluctuation compounds are discussed.