Synchrotron radiation (SR) photoemission and x-ray photoelectron spectroscopy (XPS) are used to reveal the presence of Si–OH species at the surface of aged silica. SR Si 2p spectra, recorded in the photon energy range 130 eV≤hν≤240 eV, show the coexistence of Si–O bonding states and Si–OH bonding states, the latter being marked by a component at 105.2 eV in binding energy. The intensity ratio I[Si–OH]/I[Si–O] varies monotonically from 0.24 to 0.77 with increasing photoelectron kinetic energy from 15 to 135 eV, respectively. On the contrary, no sign of silanol groups is evident in the XPS spectra, although some excess oxygen is measured in the nO/nSi atomic ratios. Combination of SR and XPS results suggest that the silanol groups lie in a region which extends approximately 16 to 21 Å from the surface, whereas the composition of the material is virtually that of silica for depths≥30 Å. Possible sources of uncertainty in the analysis of Si–OH species in silica are discussed.

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X-Ray photoelectron spectroscopy has been used to examine the surface chemical composition of chromiapillared Sn and Zr phosphates. All the materials are single-phase with Cr"' ions octahedrally coordinated in a virtually anhydrous phosphate network, independent of the chromium content and preparation conditions. Quantitative analysis of the surfaces of the materials was achieved within an accuracy of +5%. While the atomic ratios M,:M, (M,,M,=Cr, P, Sn, Zr) differ by at most 20% from the chemical composition of the starting materials, the nO:nM,(Mj) atomic ratios show a sizeable depletion (up to 50%) in oxygen content, which we interpret as being due to surface dehydration.

X-ray photoelectron spectroscopy was used to investigate how different pretreatments modify the chemical composition and bonding on silicon substrate surface and, to detect the intermediate phases present at the diamond film interface. The pretreatments were mechanical scratching with a diamond powder, ultrasonic abrasion with diamond suspension and in siru negative dc biasing. The XPS results indicated the presence of hydrocarbons and the formation of new chemical species on the Si substrates such as oxides and carbides. The very important role played by silicon carbide on diamond nucleation and growth was underlined by the phases found at the diamond films interface.

In this investigation, titanium layers with different titanium nitride phases are deposited via reactive gas plasma spraying using a statistical design-of-experiments approach to determine the effect of process parameters on coating properties. The layers are characterized by various means, showing how nitrogen concentration in the plasma gas, spraying pressure, and substrate temperature correspond with coating hardness, porosity, and nitriding levels. The values of all layer properties were found to increase with increasing nitrogen content in either the plasma gas or spraying atmosphere. Paper includes a German-language abstract.