Resonance of 4f partial photoionization cross section of Yb and Eu near the 5p threshold

The 4f partial photoionization cross section of the divalent metals Yb and Eu are measured by photoelectron spectroscopy in the 15 to 30 eV range. Both metals show the same resonance effect above the threshold of the first peak of the 5p multiplets in spite of different configurations of valence electrons: the appearance of a replica of the valence band region at fixed kinetic energy arising from a 5p core hole induced Auger-like decay process. An apparently dissimilar resonance effect is observed above the second peak of the Eu 5p multiplets: no clear feature except a weak enhancement of 4f peak intensity similar to the 4d\ue2\u80\u94Af resonance in oxidized Yb. It is possible that similar process effects exist in all the lanthanides