Chemical effects of high‐resolution Yb Lγ ₄ emission spectra: a possible probe for chemical analysis

An ‘eccentric’ X‐ray emission, YbLγ₄, was measured for Yb metal, Yb₂O₃, YbF₃, β‐YbAlB₄, YbNi₃Al₉, and YbNi₃Ga₉ with a resolution of ~0.9 eV. Peak splitting of the YbLγ₄ line was observed in all the recorded spectra and was attributed to the two components originating from the LS coupling of the Yb5p hole, the Yb5p_1/2 (L_IO_II: Lγ₄′) and Yb5p_3/2 components (L_IO_III: Lγ₄). The spectra were substantially different depending on the chemical environment of Yb. The position of the Lγ₄ + Lγ₄′ band shifts depending on the valence of Yb (v): ~4.4 eV from divalent to trivalent. The Lγ₄ + Lγ₄′ spectra of the mixed valence intermetallics, i.e. YbNi₃Ga₉ (v = 2.59) and β‐YbAlB₄ (v = 2.75), were fairly well reproduced by averaging the spectra of divalent Yb and trivalent YbNi₃Al₉, which suggests the possibility of using the YbLγ₄ emission for determining the valence of Yb intermetallics. In trivalent Yb compounds, the relative intensity of Lγ₄ compared with that of Lγ₄′, as well as the appearance of a high‐energy satellite, was found to be influenced by the ligands around the Yb ions. With the aid of preliminary atomic multiplet and band structure calculations, the differences in the valence band structure and resultant screening effects on the O_II,III⁻¹ states were determined to be the possible causes for the observed ligand dependence. © 2013 The Authors. Polymers for Advanced Technologies published by John Wiley & Sons, Ltd.