Photoluminescence and molecular orbital theory in anodic oxide films formed on aluminium

Abstract

We use molecular orbital theory (MOT) to explain the existence of one or two excitation maxima in photoluminescence excitation spectra of Al2O3 formed on Al in different aqueous electrolytes (H2SO4, H3PO4, H2CrO4, Na2CO3, H2C2O4 and HCOOH). All oxides were formed at the same temperature and current density. Comparing experimental and calculated values of the maximum of the excitation wavelength λmax we concluded: (a) that structural change in the formed oxides occurred; (b) that differences in λmax are in connection with different types of incorporated anions or anion fragments.