Pressure effects on aluminium oxidation kinetics using X-ray photoelectronspectroscopy and parallel factor analysis

The effects of water vapour pressure on oxidation kinetics of aluminium hav e been studied using X-ray photoelectron spectroscopy (XPS) and three-way p arallel factor analysis (PARAFAC). While the first technique is a powerful experimental tool for surface oxidation studies, the PARAFAC technique is a sophisticated analytical tool for analysing XPS data. The XPS Al(2p) and O (1s) core level have been used to follow the oxide film growth on clean sur faces at room temperature as a function of oxidation time (ranging from 1 t o 60 min) and pressure of water vapour (ranging from 2.0 x 10(-6) to 6.5 x 10(-4) Pa). The growth of thin oxide films on aluminium surfaces has been f ound to follow the Cabrera-Mott inverse logarithmic law in all pressure ran ges studied. The pressure effects have shown that the defect formation reac tion at the oxide film/gas interface is the rate determining process in the aluminium oxidation. The pressure dependence of oxidation kinetics can be explained on the basis of metal vacancies in the defect structure of thin a luminium oxide films. (C) 1999 Published by Elsevier Science B.V. All right s reserved.