X-Ray Absorption Near Edge Structure Spectra as a basis for the speciation of lead

For this study several inorganic lead (II) compounds were measured at the Pb-L₃-(13035 eV), L₁- (15860 eV) and M₅- (2484 eV) edge using X-Ray Absorption Near Edge Structure Spectroscopy (XANES) to determine experimentally which edge is most sensitive to the coordination environment. Each edge probes a different electronic configuration because of the selection rules and has a different resolution because of life-time broadening. Pb-L₁-XANES spectra are only sensitive to the first coordination shell. Pb-M₅-XANES spectra show a better energy resolution which is due to decreased lifetime broadening, but the pure lead spectra are also sensitive only to the first coordination shell. Spectra at the Pb-L₃-edge show the highest sensitivity: differences in coordination out to the third shell could be distinguished. Therefore, even though Pb-L₁- and M₅-edges have some advantages, because of physical conditions compared to the L₃-edge, these advantages do not result in increased sensitivity.