| AVS 60th International Symposium and Exhibition | |
| Applied Surface Science | Tuesday Sessions |
| Session AS-TuM |
| Session: | Developments in Electron Spectroscopies for Non-Ideal Samples |
| Presenter: | A. Rossi, Università degli Studi di Cagliari and ETH Zurich, Italy |
| Correspondent: | Click to Email |
For decades it has been well known that the presence of layers of nanometer thickness can dramatically change the functional properties of a material, i.e. the corrosion resistance in aggressive environments, the wear and friction properties and more recently the leaching of minerals, the protein resistance and the biocompatibility of an implant.
Recent advances in x-ray photoelectron spectroscopy (XPS) enable examination of surface-chemical properties with far greater spatial resolution and accuracy than ever before, allowing the development of analytical strategies for understanding the mechanisms of surface-chemical reactions. These results offer unique possibilities for tailoring the surface properties of materials and for designing more sustainable and environmentally benign chemicals.
This presentation will focus on the most recent results: some of them are unpublished and others are already published within the framework of collaborations with other groups.
From XP-spectra to thickness and composition of nanostructured materials and of solutions
One of the unique characteristics of XPS is its capability of providing information on the thickness and composition of materials with layers of nanometer thickness in a non-destructive way. In this presentation, I will discuss the results of the research performed with the aim of understanding films only a few nanometers thick. Topics are the chemical-state identification of different elements and the ordering of molecules within the films. Examples from our research on multi-component alloys, including ‘real systems’ such as steels, self-assembled monolayers (SAM) and organically functionalized bio-surfaces will be presented. The mathematical algorithms will be critically evaluated for practical applications.
Very recent angular-resolved XPS results of tetraethyl-ammonium bromide (TEABr) in polyethylene glycol (PEG) 200 are shown to demonstrate the spatial distribution at the vacuum-solution interface.
Imaging XPS: the importance of visualization of chemical information
Imaging XPS is one of the most powerful tools that are available nowadays for investigating the surface of heterogeneous samples. Chemical maps recorded on steel samples after tribological testing at pressures of some GPa and up to 150°C are processed with principal component analysis, allowing the identification of polyphosphates with different chain lengths and the reconstruction of compositional and thickness maps. The relevance of these results for the development of new, more environmentally compatible and sustainable anti-wear and friction modifier additives will be discussed.