X-ray L3-absorption spectra of tetravalent lanthanides in metallic compounds

Absorption spectra of metallic and non-metallic compounds of cerium, praseodymium and terbium are considered, possible causes of their difference are discussed. It follows from X-ray L3 absorption spectra of cerium and praseodymium in CeCo5 and PrCo5 as well as of cerium in Ce2Co7, Ce2Co7 and CeCo2Si2 that cerium ions and probably praseodymiuM ions are in intermediate valency states. Magnetic moment absence at cerium ions in CeCo5 testifies to the fact that the state of homogeneius intermediate valency is realized in this compound. Comparison with absorption spectra of cerium and praseodymium in oxides leads to the conclusion that the final state of absorption transition in four-valent ions in metallic compounds is relaxed and is achieved during the electron transition from surrounding atoms to atoms with an X-ray induced vacancy