Calcium L-edge XANES study of some calcium compounds

The Ca L_3,2-edge XANES spectra of six calcium salts have been measured in both total electron and fluorescence yields using a high-resolution spherical grating monochromator. The compounds investigated were; CaF₂, CaCO₃, CaCl₂ 2H₂O, calcium phosphate, calcium glycerophosphate and calcium gluconate. We find that the fine structure of the Ca L_3,2-edges for each compound is unique and relates to the local structure of the Ca atom. The implications of these results to the study of the structure of calcium binding sites in systems of biologically interest will be discussed.