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  • Polymer and Materials Science  (6)
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  • 1
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 19 (1992), S. 139-144 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: In the smelting of aluminium, HF fumes are produced that are subsequently trapped by absorption onto alumina. The factors that affect the adsorption capacity of alumina have been studied previously and are well established, but the mechanism by which HF adsorbs onto the alumina surface is not well understood.In this study, x-ray photoelectron spectroscopy (XPS) was used to investigate the nature of the surface adsorption of HF on alumina. XPS is particularly well suited to the study of this type of gas adsorption process.Laboratory-prepared samples were studied with particular interest in evidence for Al—F bonding, or in fluoride species formed by reaction with —OH or —O. Also of interest was the role of sodium, since it is segregated to the surface of the alumina during calcination.Al—F bonding was observed on only one sample type. An Al—F interaction was identified when the alumina had been predried and dry HF was absorbed. When moisture was present no AlF3 formation was observed. This suggests that under conventional conditions (i.e. moisture present) the adsorption of HF involves a weak interaction, probably hydrogen bonding, with intermediate layers of water. After heating the samples containing weakly bound HF to 500°C, no Al—F interaction was observed. Much of the HF was desorbed at 700°C.An Na-F interaction was observed in all fluoride-adsorbed samples; however, this can only account for a small proportion of the total fluoride adsorbed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 5 (1983), S. 181-185 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A new approach to the suppression of molecular ions in secondary ion mass spectra of insulating specimens is reported. Using a Cameca IMS 3f instrument, with unconventional primary beam conditions and uncoated samples, it has been possible to almost eliminate the contribution of molecular ions to the mass spectrum. This has resulted in excellent discrimination for major and trace element detection in these materials, including complete resolution of the rare earth elements in a number of minerals.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 25 (1991), S. 1069-1084 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The tissue response to an implant may involve both physical and chemical factors. There is little reliable information on the effects of these parameters and the associated ionic release on the cell-material interaction because the majority of studies have not fully characterized the implant material. In this work surface spectroscopy using ISS, ESCA, and SIMS was carried out on Ti6A14V, Co-Cr-Mo, Al2O3, and hydroxyapatite dental implant materials that had been subjected to six commonly used preparative procedures. The results showed that each procedure generated an individualistic composition for the outermost surface of each material. These differences could be significant in cellular and tissue response. Improved understanding of these factors requires defined and reproducible surfaces.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Recent experiments have shown that secondary ion mass spectrometric (SIMS) measurements of insulator surfaces can be greatly facilitated by the use of a charged aperture located immediately above the analysis area (the ‘specimen isolation technique’). This allows the surface potential within the aperture area to be stabilized. Charging is stabilized when the potential difference between the surface and the aperture becomes large enough that excessive charge, in the form of secondary electrons, is drained away from the surface to the aperture. The potential difference generated on such insulating surfaces can be measured experimentally by varying the voltages applied to the electrostatic analyzer to measure the secondary ion intensity as a function of kinetic energy. Such measurements have been carried out on a Cameca IMS-3F instrument for a range of aperture dimensions and for different primary and secondary ions. The surface potential can be stabilized at a potential readily measurable by the electrostatic analyzer for both O- and Cs+ ion beams. The mechanism for this stabilization has been analyzed through calculations of two dimensional contours for the region around the specimen holder. For surfaces with a very high charging potential (〉600 V), potential wells which can trap ions of low kinetic energy develop near the surface. Element and oxide secondary ion kinetic energy distribution curves, taken under specimen isolation conditions, which differ from those obtained under normal non-charging SIMS conditions, are evidence for such ion trapping.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 7 (1985), S. 69-73 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Strong suppression of molecular ions in positive secondary ion mass spectra (SIMS) is achieved by electric isolation of a specimen (SI) with an electrically charged aperture situated immediately above its surface. This technique is also useful for controlling the surface charging on an insulator. The origin of this phenomenon has been explored using metals and semiconductors as models. The strong molecular suppression effect is found to result from the very high ion kinetic energies (〉400 eV) emerging from the surface under SI conditions. The charged aperture is believed to stabilize surface charging by confining it within a small region. SI methods for reducing molecular ions in silicon and mild steel specimens reduce major molecular fragments by 3-4 orders of magnitude.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 18 (1992), S. 262-268 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Specimen isolation (SI), an extreme form of kinetic energy filtration, has been shown to be an effective tool for controlling the problems of sample charging and molecular interferences often encounted in secondary ion mass spectrometry (SIMS). In this study the mechanisms involved in the charge stabilization, under both positive and negative primary beam bombardment, were examined more closely. This was facilitated by the introduction of a resistor into the SI configuration, allowing for in situ sample potential control, and the use of computer simulations. The formation of low-energy ion traps at the sample surface under extreme SI conditions was also directly recorded, showing good agreement with the computer simulations carried out.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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