The experimental information available from x-ray photoemission spectroscopy regarding the electron correlation energy U of $3d$ and $4f$ electrons in solids is considered. It is found that U is of the order of 7 eV for $4f$ electrons and {~} 2 eV for $3d$ electrons.
No takes yet. Share an insight, caveat, or question.
Hüfner et al. (1973) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: