X-ray Fluorescence Analysis of Hexavalent Chromium Using K(beta) Satellite Peak Observed as Counterpart of X-ray Absorption Near-Edge Structure Pre-Edge Peak

摘要

A K(beta) satellite peak in X-ray fluorescence (XRF) spectra is observed as a counterpart of the pre-edge peak of the X-ray absorption near edge structure (XANES). In K(beta) emission of chromium, a small satellite peak is observed at 5.983-5.988 keV only for hexavalent chromium compounds such as CrO_(3), Na_(2)CrO_(7)(centre dot)2H_(2)O, Na_(2)CrO_(4)(centre dot)4H_(2)O, K_(2)Cr_(2)O_(7), K_(2)CrO_(4), Zn_(2)CrO_(4)(OH)_(2)(centre dot)2H_(2)O, PbCrO_(4), and BaCrO_(4), together with the main peak at 5.947 keV, while trivalent chromium compounds such as Cr_(2)O_(3) and Cr(OH)_(3)(centre dot)nH_(2)O show only the main peak at 5.947 keV. This corresponds to the fact that the K pre-edge peak in XANES is observed only for the hexavalent chromium compounds. The electronic level causing the satellite peak is almost at the same energy level as that causing the pre-edge peak. Our finding not only affects the interpretation of the origin of the pre-edge peaks but also leads to the simple speciation method of chromium compounds using XRF.