Grazing-incidence XAFS studies of aqueous Zn(II) on sapphire single crystals

Abstract

Grazing-incidence XAFS was applied to study the sorption of Zn(II) on two crystallographically distinct surfaces of highly polished sapphire single crystals as a simplified analog for metal ion sorption on natural aluminum-(hydr)oxides. Experiments were performed both in-situ (in contact with bulk solution) and ex-situ in a humidified N 2 atmosphere. The identification of an Al shell at roughly 3Å in all samples indicates that Zn(II) binds as an inner sphere complex on both the (0001) and (1-102) surfaces. Polarization dependence of the XAFS spectra is used to propose possible sorption species.