High resolution Lα X-ray fluorescence spectra of palladium compounds

High-resolution Pd Lα (L3–M4,5) X-ray fluorescence spectra of several Pd compounds were measured on a double-crystal X-ray fluorescence spectrometer. It was found that the chemical shifts of Pd Lα1 line in Pd metal, Pd–Ag alloy, PdCl2, PdBr2, PdI2, Pd(NO3)2 and Pd(acac)2 were relatively small (less than 0.1 eV with metallic Pd as reference). We adopted the charge transfer effect to elucidate this seemingly anomalous experimental result. For divalent Pd, at the moment of the creation of a 2p−1 core hole, one or two electrons were transferred from the ligand to the central Pd atom. Therefore the divalent Pd (II, 4d8) may have valence electron configuration similar to metallic Pd (0, 4d10), and this eventually results in the small chemical shifts.