Differentiation of tin oxides using electron energy-loss spectroscopy

We have used electron energy-loss spectroscopy to search for differences in the energy-loss near-edge structure of SnO, SnO 2, and an intermediate oxide, with a view to distinguishing them unambigously. We have found that the oxygen K edge exhibits clear differences that can be used for fingerprinting each phase. The oxygen edge appears at the same position for each phase whereas a chemical shift of the Sn M 4,5 edge of about 3.5 eV was observed between phases with Sn in 2+ and 4+ oxidation states. Both observations can be used to distinguish between the three phases, allowing their on-line identification within nanostructured materials.Fil: Moreno, Mario Sergio Jesus. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Egerton, R.F.. University of Alberta; CanadáFil: Midgley, P.A.. University of Cambridge; Reino Unid

Cytochemical techniques and energy-filtering transmission electron microscopy applied to the study of parasitic protozoa

The study of parasitic protozoa plays a major role in cell biology, biochemistry and molecular biology. Numerous cytochemical techniques have been developed in order to unequivocally identify the nature of subcellular compartments. Enzyme and immuno-cytochemistry allow the detection of, respectively, enzymatic activity products and antigens in particular sites within the cell. Energy-filtering transmission electron microscopy permits the detection of specific elements within such compartments. These approaches are particularly useful for studies employing antimicrobial agents where cellular compartments may be destroyed or remarkably altered and thus hardly identified by standard methods of observation. In this regard cytochemical and spectroscopic techniques provide valuable data allowing the determination of the mechanisms of action of such compounds

Iron Oxide Nanoparticles Employed as Seeds for the Induction of Microcrystalline Diamond Synthesis

Iron nanoparticles were employed to induce the synthesis of diamond on molybdenum, silicon, and quartz substrates. Diamond films were grown using conventional conditions for diamond synthesis by hot filament chemical vapor deposition, except that dispersed iron oxide nanoparticles replaced the seeding. X-ray diffraction, visible, and ultraviolet Raman Spectroscopy, energy-filtered transmission electron microscopy , electron energy-loss spectroscopy, and X-ray photoelectron spectroscopy (XPS) were employed to study the carbon bonding nature of the films and to analyze the carbon clustering around the seed nanoparticles leading to diamond synthesis. The results indicate that iron oxide nanoparticles lose the O atoms, becoming thus active C traps that induce the formation of a dense region of trigonally and tetrahedrally bonded carbon around them with the ensuing precipitation of diamond-type bonds that develop into microcrystalline diamond films under chemical vapor deposition conditions. This approach to diamond induction can be combined with dip pen nanolithography for the selective deposition of diamond and diamond patterning while avoiding surface damage associated to diamond-seeding methods

TRENDS IN EELS WITHIN THE FIELD OF MICROANALYSIS

On présente la technique de spectrométrie des pertes d'énergie des électrons en microscopie électronique en transmission. Puis on discute les développements récents de l'appareillage et on donne plusieurs exemples d'analyse chimique et structurale.We begin with a brief introduction to electron energy-loss spectroscopy carried out using an electron microscope. Recent developments in instrumentation are then discussed, followed by examples designed to illustrate applications of the technique to elemental analysis and structure determination