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  • 1
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Various experiments show that low-energy electron-induced X-ray spectrometry (LEEIXS), using a gas discharge tube as an efficient and stable electronic excitation source, represents a powerful new technique in many fields of research related to surface and near-surface chemical characterization of materials. The instrument is a wavelength-dispersive X-ray spectrometer capable of high qualitative or quantitative performances in the soft and ultra-soft region (λ = 0.3 - 10 nm). LEEIXS applications given in this paper demonstrate how chemical, electrochemical or physical treatments of various substrates modify the solid surface composition.
    Additional Material: 20 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 10 (1987), S. 163-167 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The effects of anodization parameters, such as current density, electrolyte concentration, electrolyte temperature, and anodization time on the thickness and composition of the oxides formed on AISI 304L stainless steel anodized in H2SO4—K2Cr2O7 were studied by low energy electron induced x-ray spectroscopy (LEEIXS), glow discharge optical spectroscopy (GDOS), and inert ion sputter profiling in conjunction with Auger electron spectroscopy. The physical and chemical properties of these films were correlated with the results of mechanical tests performed on adhesively bonded structures of the anodized pieces in order to test the feasibility of anodization as a prebond treatment for stainless steel.Anodization in H2SO4—K2Cr2O7 produces a Cr(III) enriched 100 nm thick oxide film. The novel technique of LEEIXS was used to characterize the chemical state of chromium while the hydrogen content of the anodic oxide was determined by GDOS.
    Additional Material: 10 Ill.
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  • 3
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A quantitative study by reflection-absorption infrared spectroscopy (RAIRS) on multilayer systems of Langmuir-Blodgett (LB) poly(amino acid) films has been carried out. Thickness measurements of monolayer and multilayer systems have been made and the results obtained by two well-known equations have been compared. Evolution of the α-helix conformation as a function of temperature in the case of polybenzyl aspartate (PBA) and polybenzyl glutamate LB systems has also been studied by RAIRS. Finally, a Fourier transform infrared transmission study on PBA LB multilayers as a function of temperature has allowed us to draw some conclusions on the orientation of the C=O bonds (amide I) with respect to the dipping direction.
    Additional Material: 8 Ill.
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  • 4
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Stainless-steel substrates were surface treated then coated with thin amorphous hydrogenated carbon films that were deposited by CH4 plasma polymerization. The effects of these surface treatments were studied by x-ray photoelectron spectrometry, ion scattering spectrometry and Fourier transform infrared spectrometry. A few minutes of O2 plasma treatment at a power density of 0.5 W cm-2 was shown to modify strongly the surface composition of these substrates, with chromium present at the surface being transformed gradually, from Cr2O3 to CrO3, before disappearing altogether. In contrast, NH3 plasma of similar power, but generated over a few seconds, cleaned and functionalized the surface. Both of these treatments proved to be highly efficient in promoting good carbon film adhesion to the substrate.
    Additional Material: 15 Ill.
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  • 5
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: In order to promote strong and durable steel/epoxy adhesive joints, various stainless steel surface treatments are investigated. The adherend surface characterization is achieved by both spectroscopic (low energy electron-induced x-ray spectrometry (LEEIXS), AES, XPS) and microscopic (SEM) techniques. The strength of the steel/epoxy bonds is evaluated, after bonded sample ageing under hydrothermal conditions (70°C, 95% r.h.), by means of a mechanical three-point flexure test, sensitive to the interfacial properties of the bonded systems.The stainless steel surface treatments used in this study include conventional ones, such as solvent degreasing, acid etching, and phosphating and more original ones such as anodizing in sulphuric-chromic or nitric acid electrolytes. These two last treatments lead to the formation of a ‘thick’ (in the range 10 to 90 nm) surface layer, highly chromium (as Cr(III))-enriched, as determined by LEEIXS and XPS.The anodized stainless steel/epoxy systems exhibit performances which largely outclass those allowed by conventional steel prebonding treatments. These performances are very dependent upon the electrochemical conditions (current density, treatment duration, electrolyte temperature and composition) chosen for the anodizing process.
    Additional Material: 8 Ill.
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  • 6
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: We report high-resolution XPS data on three forms of the electrochemically synthesized polyaniline films: the highly conducting emeraldine salt form and the films obtained after KOH treatment and electrochemical reduction in HCI. The deconvoluted N 1s peaks in these films show clear evidence of the existence of the existence of four states of nitrogen, which are attributed to the amine, polaron and localized bipolaron defect configurations. The trends observed after the KOH treatment and electrochemical reduction in HCI in the N 1s spectra, plus the C 1s and O 1s peak shapes, support this assignment scheme.
    Additional Material: 3 Ill.
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  • 7
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Low-energy electron-induced x-ray spectrometry (LEEIXS) is a soft and ultrasoft x-ray emission technique. The wavelength-dispersive x-ray spectrometer used is equipped with a cold cathode tube. This device acts as an excitation source by bombarding the sample surface with a quasi-monoenergetic electron beam, the energy of which is selectable over the range from 0.5-5 keV. The probed depth, depending among other parameters upon the incident electron beam energy and upon the sample nature, typically ranges from 5 to 150-200 nm, the probed area being ∼1 cm2. The capabilities of this technique in the fields of atomic and molecular surface analyses have been shown for a wide range of applications. The aim of this paper is to point out the ability of this technique to solve some problems dealing with the near-surface analysis of insulating materials and, more particularly, of some metallic oxides.
    Additional Material: 10 Ill.
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  • 8
    ISSN: 0142-2421
    Keywords: methane ; catalytic combustion ; hexa-aluminate ; manganese ; LEEIXS ; XPS ; auger parameter ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: In order to achieve a good activity with respect to methane combustion, a good route would be via catalysts incorporating transition metals. For devices operating at high temperatures, such as gas turbines, substituted hexa-aluminates present the advantage of good thermal stability when compared to impregnated Al2O3. For the purpose of this study, manganese-substituted hexa-aluminates were prepared either by the sol-gel method or by carbonate precipitation. Surfaces were analysed by soft x-ray emission, namely low-energy electron-induced x-ray spectroscopy (LEEIXS), and by photoelectron spectroscopy, namely x-ray photoelectron spectroscopy. The results on samples incorporating increasing amounts of manganese show the existence of an upper limit to the number of atoms substituted at the catalyst surface. This limit is about 2.7 manganese ions per unit cell, for samples prepared either by the sol-gel or by the carbonate precipitation technique and then calcinated at 1200°C. The interpretation of the Auger parameter variations shows that the relative amount of Mn in oxidation state III increases when the surface amount of Mn increases, as well as with the Mn substitution level. This fact can be related to an increased activity for methane conversion. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
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  • 9
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The surface of hot-dip galvanized steels is a complex system highly dependent upon the composition of the galvanization bath and upon surface treatments such as degreasing, alkaline etching and chromate conversion. In this study, industrial zinc-coated samples are subjected to degreasing, alkaline etching and chromating and then characterized by XPS and Fourier transform infrared spectroscopy (FTIR). Their surface reactivity is studied by vapourphase adsorption of probe molecules, either basic (pyridine) or acidic (phenol), and FTIR analysis. The reactivity enhancement following the alkaline etching is clearly evidenced by this technique. In order to gain information upon the reactivity of the hot-dip galvanized steel surface towards some organic components of epoxy resins, dicyandiamide adsorption was performed at 180°C on the chemically treated substrates. As suggested by the results obtained with probe molecules, alkaline etching of galvanized steels allows a dicyandiamide-zinc reaction leading to the formation of a defined complex. In addition, the study of the interaction of model substrates (pure zinc and aluminum-contaminated pure zinc) with dicyandiamide clearly shows that surface contamination of galvanized steels by aluminium is responsible for the inhibition of the dicyandiamide-zinc reaction.
    Additional Material: 12 Ill.
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