Interpretation of photoemission and bremsstrahlung isochromat spectra of uranium compounds

Bremsstrahlung isochromat (BIS) and U 4f core-level photoemission (PE) spectra of UPt and UPt₅ are presented and compared with corresponding data---including U 5f valence-band PE spectra---of UBe₁₃, as well as with the results of band-structure calculations. The shapes of the BIS, U 5f, and U 4f PE spectra are consistently explained in terms of two differently screened final states, namely an f-screened main peak reflecting the delocalized 5f part of the electronic ground state, and a poorly screened satellite increasing in intensity with decreasing 5f hybridization. The considerably higher relative intensity of the f-screened main peak in 5f PE as compared to BIS spectra is readily explained on the basis of the degeneracies of the relevant 5f screening orbitals in U compounds. The positions of the poorly screened satellites relative to the f-screened main peaks in BIS spectra are found to be related to those of the Pr 4f³ BIS multiplets in homologous Pr compounds, i.e., they reflect chemical shifts. It is also realized that the relative intensities of these BIS satellites follow those of the satellite peaks in U 4f core-level PE spectra.