A XANES investigation of the bonding of divalent lead in solids

Abstract

XANES (X-ray absorption near-edge structure) spectra of divalent lead compounds have been studied at both the Pb LIII and LI edges using synchrotron x rays from CHESS (Cornell High Energy Synchrotron Source). The combined LIII and LI near-edge spectral features strongly support a sp3d2 hybridization scheme in covalently bonded yellow PbO. The absorption features associated with the spectra of ionic halides (PbF2, PbCl2, and PbI2) and the oxysalts [Pb(NO3)2, PbSO4, and PbCrO4] have been shown to be consistent with crystal field splittings of the final states using group theoretical arguments. The XANES spectra of a series of PbO–PbCl2 glasses have also been studied to elucidate the nature of bonding and confirm the local structure derived from x-ray diffraction experiments. Shape resonance features associated with LIII and LI edge XANES have also been discussed. This investigation illustrates the novel use of XANES spectroscopy in studying the bonding of nontransition metal ions.