Cu k-edge xanes and electronic structure of trivalent, divalent, and monovalent cu oxides

Abstract

To elucidate the electronic structure of copper oxides with formally trivalent, divalent and monovalent Cu, x-ray absorption spectra were measured for NaCu02, CuO and Cu20 by using synchrotron radiation. These XANES spectra were investigated by performing ab initio quantum chemical calculations based on the cluster-CI theory. The ground state of NaCu02 demonstrates strong covalent bonds between the Cu 3d and O 2p orbitals, resulting in small contribution of Cu(d8) configuration and large contribution of Cu(d9) configuration.The final-state effect in the Cu K-shell excited states of NaCu02 is similar to that of CuO, which explains that the overall structure in the spectrum of NaCu02 resembles that of CuO. On the other hand, the ground state of Ci^O demonstrates covalent bonds between the Cu3d, Cu4s and O2p orbitals, resulting in a contribution of the Cu d94s configuration. This configuration causes another type of final-state effect in the Cu K-shell excited states of Cu20. © 1993 The Japan Society of Applied Physics.