The Effect of Multiplet Splitting of the 4d Levels in Rare Earth Elements on Their X-Ray Spectra

Abstract

The rare earth elements are characterized by partially filled 4f shells which give rise to an exchange interaction between the 4f and 4d levels. This interaction results in the splitting of the 4d₃/₂, 4d₅/₂, 4f₃/₂ and 4f₇/₅ atomic levels, thus generating electronic subshells which are found in the atoms of the rare earth elements only. As a result, the x-ray spectra of these elements exhibit emission lines which are not to be found in any other element. The energy and the relative intensity of these lines, which are observed on the low energy side of the Lγ₁ and Lβ₂ diagram x-ray lines, have been measured and compared with the results of a simple theory based on the exchange integral and the total spin of the 4f electrons.