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In photoemission, the Auger electron energy, combined with the respective photoelectron energy, provides the so-called Auger parameter α ′ which in the case of 3d transition metals, has been demonstrated to be influenced by the coordination state of the emitting atom. In the literature of electron spectroscopy for chemical analysis studies on titanosilicates, the Ti Auger parameter has typically not been reported. In this work, the X-ray photoelectron and the X-ray induced Auger electron spectra of a Ti silicalite (TS-1) and other crystalline mesoporous titanosilicates such as TiSBA-15 and TiMCM-41 have been measured. An α ′ value of 882.3 eV, ∼10 eV higher than in TiO 2 , has been found for part of the titanium in TS-1 and TiSBA-15 samples. Such a shift in the Auger parameter is attributed to tetrahedral coordination of Ti, substituting for Si atoms in the framework.

Core-level photoemission peaks taken on several insulators with spatial resolution of 30-300 mu m rigidly shift in energy from place to place, most likely because of local charging effects. Such phenomena can affect the linewidth and the general lineshape of conventional, spatially integrated spectra even when a flood gun is used, which is one of the standard remedies against charging. This may require a critical revision of photoemission linewidths and lineshapes for many past experiments on insulators.

The analysis of interfaces between silicon carbide or carbon fibres and a glassy sol-gel derived SiO 2 matrix in ceramic matrix composites (CMC) is presented. The x-ray photoelectron spectra (XPS) indicate a differential charging effect on all samples, potentially related to the adhesion strength at the interface. By Auger electron spectroscopy (AES) a silicon oxide layer is found on the surface of SiC fibres while no oxygen is detected on the C fibres. Effects of ageing in air or nitrogen at high temperature for 100 h were also studied. While no crystalline phases are present in the x-ray diffraction (XRD) patterns of sintered samples before ageing, different amounts of an SiO 2 (low cristobalite) phase appear on beating at 1200 o C in air or in N 2

The application of SAM and XPS to the study of powder mixtures composed of silicon carbide and processing additives is presented. The density of sintered SiC specimens has been shown to be related to the surface composition of the freeze-dried mixtures, measured after milling the water slurries and after heating for the removal of binding polymers (dewaxing). Effects of milling and dewaxing on the dispersion of sintering aids, on the formation of residual carbon layers and on the evolution of the surface oxide have been tested by XPS while the spatial distribution of surface carbon species has been tested by SAM. The procedure for the acquisition of Auger spectra and linescans on these powder samples is described. SAM analysis of dewaxed SiC greens, reveals the presence of graphitic carbon agglomerates with an average diameter of roughly 5 μm after 1 h of mixing in attrilion mill which decreases to less than 1 μm after 16 h. The study shows that processing parameters such as type and concentration of sintering aid, milling time and dewaxing procedure can be optimized using the information of surface spectroscopies, acquired after each step of processing, for the production of high density specimens.

Ceramic powder mixtures composed of silicon carbide and processing additives such as boron, carbon and binding agents were investigated by X-ray photoelectron spectroscopy. The novelty of this work consists in the application of a surface analysis technique to the study of ceramic green bodies. The analysis of freeze-dried powders, obtained from aqueous suspensions of the mixtures, reveals a strong C1s lineshape dependence on the carbon dispersion and the milling procedure, which are important factors in the fabrication of high-density SiC components. In fact, the deconvolution of C1s bands allows a quantification of the spectral contribution of four carbon species assigned to C-Si, C-C, C-H and C-O species, so that a relative measure of the dispersion of carbon on the surface of the SiC particles is obtained. When carbon black or graphite are used as carbon additives it appears that carbon black is more dispersed than graphite at shorter milling times. For all samples studied, a good correlation is shown to exist between the intensity of the C-C carbon component in the C1s band and the density after sintering.

The alkali metal distribution in a variety of alkali doped ZnO catalysts has been studied and is shown to affect total methane conversion and C2 selectivity. When Na 2 CO 3 precursors are used, CO 3 2− groups decompose upon calcination and sodium penetrates into the ZnO matrix, even at high loading. In the case of lithium, layers of Li 2 CO 3 , proportional to the Li concentration, segregate on the ZnO and reduce the oxide active surface available for gas reaction. In the aim of determining the best preparation and reaction parameters a correlation between XPS evidences and catalytic data collected during the initial phase of reaction was attempted.

Publisher Summary The use of fossil fuels at a global level causes a CO2 yearly emission in the atmosphere of about 25 Gt. Fossil fuels provide for 85% of the world's energy needs, and no alternative energetic sources have the potential for a notable substitute in the foreseeable future. Among the different options under examination, the one considering capture and sequestration of CO2 originated by point sources, like power plants and refineries, is gaining increasing interest. Such an approach could allow for the pursuance of fossil fuel utilization without the feared drawback of dramatic climatic changes. Key issue in this approach is the identification of a new efficient and convenient technology for the capture of CO2. Technologies available today, based on liquid amine solutions and finalized to the enhanced oil recovery (EOR), are considered far too expensive for large scale applications, such as in power plants. Solid sorbents, as compared to the liquid counterparts, have the potential advantages of a more efficient absorption capacity (high surface compounds allow for a high capture density), a lower energetic need in the desorption step (amine-CO2 reaction compounds are surface distributed, with easy reach by fluids and heat), and a reduced environmental impact (no loss of amine to the atmosphere during the stripping step). The strategy for designing new sorbents consisted in screening different porous solids impregnated with diethanolamine (DEA), followed by screening the selected support impregnated with a variety of different types of amines.

The new thermal analysis of thermovoltaic detection (TVD) is described and its application to various substances is presented. Basically, the technique consists of recording the EMF curve generated by the thermally decomposing sample in contact with two dissimilar metal electrodes (usually Al-Pt). The general shape of the curve, in reference to the temperature axis, enables it to be used for the qualitative identification of the substance. The curves are reproducible to within about ± 3–4% of each other. TVD curves of CuSO 4 · 5 H 2 O, [Co(NH 3 ) 6 ]Cl 3 , various polymers, organic acids, coal, tobacco, water, and ethanol are presented.

The thermal dissociation reactions of selected amino acids were studied by thermovoltaic detection (TVD), TG and DSC. All of the TVD curves except L-arginine contained a broad EMF output peak in the 200–300°C temperature range. The leading edges of the peak maxima were reproducible to within ± 1–2% while the trailing edges were reproducible to ± 20% or so. The latter was related to the irreproducible nature of the electrode-decomposition products interface. The TVD curves were not unique in that they yielded thermal analysis curves that were not inherently different from other TA techniques.

The chemical changes induced by 4-keV Ar/sup +/bombardment of the transition-metal oxyanion compounds N/sub 2/WO/sub 4/ (N = Li, Na, Ag, NH/sub 4/), Na/sub x/MO/sub y/ (M = V, Cr, Nb, Mo, Ta), and the corresponding transition-metal oxides have been investigated by x-ray photoelectron spectroscopy (XPS). Both the atomic concentrations and the binding energy shifts in the altered layer show that a steady-state composition is attained at a total irradiation dose of approx.10/sup 17/ ions/cm/sup 2/. Bombardment of all of the oxyanions resulted in reduction of the transition-metal atoms to lower oxidation states; reduction to the metallic state is observed in all cases except VO/sub 3//sup -/ and CrO/sub 4//sup 2 -/. In contrast, bombardment of the metal oxides produced lower oxidation states of the metal in some, but not all, cases. The mechanism of ion-induced decomposition is discussed in terms of the thermal spike model and the behavior of specific compounds is shown to correlate with decomposition pressure at elevated temperatures.

X-Ray photoelectron spectroscopic (XPS) studies of hydrated, dehydrated and, reduced Cu NaY zeolites were carried out. With sufficient analyzer resolution, both the Cu 2 p 1 2 and 2 p 3 2 transitions were resolved into two components in hydrated CuNaY. The higher-binding-energy component and the shake-up satellites decreased in intensity with dehydration. By correlation with electron spin resonance (ESR) and X-ray diffraction results the higher-binding-energy component is assigned to octahedrally coordinated Cu2+ in the large α-cages of the zeolite and the lower-binding-energy component to tetrahedrally coordinated Cu2+ in the small β-cages of the zeolite. On hydrogen reduction of dehydrated CuNaY the XPS transitions shift by 1 eV to lower binding energies which correlated with an order of magnitude decrease in the Cu2+ ESR intensity. These shifted transitions are assigned to Cu+ or possibly to Cu0.

This report presents the project for the development of a combined facility consisting of a high spatial resolution soft x-ray scanning photoelectron microscope (SPEM) and a scanning tunnelling microscope (STM) that is going to be built in an ultrahigh vacuum (UHV) station on one of the undulator beam lines at ELETTRA, Trieste. The photon microprobe for SPEM will be generated using a zone plate diffraction optic. A special design of a spherical grating monochromator will provide the source for illuminating the zone plate. The emitted photoelectrons will be detected and analysed using a high-energy resolution hemispherical analyser with a large acceptance angle. The performance of the SPEM is projected to be as follows: (1) a photon spot size on the sample of ∼50 × 50 nm2; (2) a tunable photon energy range of 200–800 eV, with an energy resolving power of 3000 at the carbon K-edge; (3) a photon flux in the spot that is > 109 photons s−1 (0.1% body wt.)−1. The projected performance of the STM instrument ensures a lateral resolution better than 2 A. The combination of SPEM and STM techniques will enable chemical and structural mapping within the same microscopic areas of the sample surface. Descriptions of the main beam line components together with some examples of possible applications of this unique tool are included in the paper.