On the origin of the differences in the Cu K-edge XANES of isostructural and isoelectronic compounds

Cu K-edge x-ray absorption near-edge structure (XANES) spectra of trigonal (3R) CuScO2 and CuLaO2 and of hexagonal (2H) CuScO2 were investigated experimentally and theoretically, in order to study differences between spectra of isostructural and isoelectronic compounds. Significant differences were found in the Cu K-edge XANES of 3R CuScO2 and 3R CuLaO2; these differences can be understood by considering the calculated polarization dependence of the XANES spectra and the differences between the phaseshifts of Sc and La. Spectra of the 3R and 2H polytypes of CuScO2 differ only weakly and the difference originates from the long-range order. The pre-edge peak around 8980 eV is generated by the same mechanism as the pre-edge peak in Cu2O, i.e. involving scattering by the Cu atoms in the plane which is perpendicular to the O-Cu-O axis