Mixed-valence and hybridization effects in the early rare earths as studied by x-ray absorption and photoelectron spectroscopies
L/sub III/ absorption measurements on a number of Ce-based systems together with their La and/or Pr isomorphs, show that the double peaked Ce-edge is not caused by final-state shakeup processes. Shakedown satellites were identified in the absorption edges of LaNi/sub 5/ and LaPd/sub 3/ by comparing to isomorphs of heavier rare earths. The observed smallness of final-state effects implies that the method of L/sub III/ absorption is both a convenient and reliable method for measuring the mixed-valent quotient. XPS and L/sub III/ absorption measurements were performed in a system where the electronic bandstructure can be varied continuously; namely Ce(Pd/sub 1-x/ T/sub x/)/sub 3/ where T = Rh or Ag. The shakedown intensities in the Ce 3d core levels were correlated with the mixed-valent behavior in this system. The two peaks in the 4f-derived photoemission in Ce-based systems have been a major puzzle in the understanding of these mixed valent effects. Several theories have tried to explain this phenomenon. Resonant valence-band photoelectron measurements were performed on the systems REAl/sub 2/, RERu/sub 2/ and REPd/sub 3/ (RE = La, Ce, Pr, and Nd). One observes the biomodal 4f spectrum in PrAl/sub 2/, PrPd/sub 3/, and NdPd/sub 3/, as well as in the Ce-isomorphs.
- Research Organization:
- Polytechnic Inst. of Brooklyn, NY (USA)
- OSTI ID:
- 5492065
- Country of Publication:
- United States
- Language:
- English
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