Nature of galvanoluminescence of oxide films formed by aluminum anodization in inorganic electrolytes

Abstract

The presented results of our galvanoluminescence (GL) measurements of oxide films formed by anodization of high purity aluminum samples annealed at 550°C in inorganic electrolytes show that the sudden rise in the formation of y alumina crystalline regions is strongly related to the appearance of GL. We have recorded GL spectra and observed six intensive and broad emission band peaks around 430, 483, 544, 575, 601, and 648 nm. A semiquantitative analysis based on literature data on simple molecular species involving the Al atom, as well as those atoms whose presence is possible under given experimental conditions (hydrogen, oxygen, etc.) showed that GL could be caused by transitions in molecules AlH, AlO, Al2, and AlH2, possibly contained in the pores of the γ alumina crystal islands. © 2007 American Chemical Society.