Interpretation of Oxygen K pre-edge peak in complex oxides

A controversial pre-edge peak has often been observed at the O K-edge in absorption spectra from complex oxides. We study this feature in both K2O–SiO2 glass and MgAl2O4 spinel crystals. Our time-resolved energy-loss spectroscopy (EELS) results indicate that the pre-edge peak is due to radiation damage, rather than from any intrinsic feature of the material. It is assigned to the π* peak due to the O–O interaction.