Application of parallel factor analysis and X-ray photoelectron spectroscopy to the initial stages in oxidation of aluminium - II. The O 1s photoelectron line

Three-way parallel factor analysis (PARAFAC) has been used to decompose sev eral series of XPS O 1s spectra obtained in the study of oxidation of alumi nium by water vapour. Reaction time, reactant pressure and binding energy i n the XPS spectrum are the independent variables. Four factors have been ex tracted that characterize the oxidation process of aluminium by the interac tion of water vapour. Two of these factors are associated with the formatio n of a lattice oxide, either on a metal surface or on a hydrided metal surf ace. The other two factors result from attachment of OH groups either to a metal surface or to the oxide. All factors extracted have a dual functional ity: the oxide (or hydroxide) component and a water component, the latter a rising from water produced in each reaction. The PARAFAC analysis was essen tial in isolating the separate effects of pressure and time on the oxidatio n process. Copyright (C) 1999 John Wiley & Sons, Ltd.