Investigation of anodic alumina by a photoluminescence method: II

Photoluminescence emission spectra of anodic oxide films on aluminium were measured under the conditions where an interference of the Lummer-Gehrke type takes place (the emission angle was approximately equal to the total reflection angle). Both barrier (obtained in 0.1 M ammonium tartrate) and porous (obtained in 0.1 M oxalic acid) oxide films were investigated. From the positions of sharp interference maxima and minima in the emission spectra, a very precise determination of film thickness d and anodization rate ? is possible. The ? values obtained (?₁ = 1.33 nm V^-1 in ammonium tartrate; ?₂ = 0.317 nm min^-1 in oxalic acid) are in excellent agreement with the results of other workers and with our previous results obtained by other luminescence methods. This procedure is more precise than the photoluminescence method described previously and it does not need any assumption about the spatial distribution of photoluminescence centres.