THE NATURE OF THE SURFACE-ACIDITY OF ANODIZED TITANIUM - AN XPS STUDYUSING 1,2-DIAMINOETHANE

The nature of the surface acidity of freshly anodised and thermally an nealed anodised titanium was investigated using X-ray photoelectron sp ectroscopy. 1,2-Diaminoethane (ethylenediamine) was used as a basic ni trogenous probe capable of producing both Lewis and Bronsted interacti ons with acidic surface sites. Comparison with wet polished copper ind icated that both Lewis and Bronsted acid sites were present within the anodised titanium surface region. Thermal annealing under vacuum appe ared to have little effect on the number of available Lewis sites, but substantially reduced the number of Bronsted sites. This was related to dehydroxylation of the surfaces: and indicated that strongly Bronst ed acidic hydroxyl groups are present on anodised titanium surfaces.