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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 2 (1993), S. 313-318 
    ISSN: 1057-9257
    Keywords: MOCVD ; MAS-NMR ; CARS ; Quantum effects ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Coherent anti-Stokes Raman scattering (CARS) has been utilised to monitor the decomposition of trimethylgallium (TMGa) on the reactive internal surface of the protonated form of zeolite Y under metal organic chemical vapour deposition (MOCVD) conditions designed to produce GaP deposits that exhibit quantum-size effects. The CARS data clearly reveal the facile room temperature decomposition of TMGa in the zeolite, as evidenced by the detection of increasing levels of methane with increasing reaction time. In addition, the zeolite samples were analysed by solid state nuclear magnetic resonance with magic angle spinning (MAS NMR) before reaction, after reaction of TMGa and after subsequent reaction with phosphine at 300°C. These data reveal that TMGa reacts with acid sites in the zeolite 12-rings, resulting in species containing methyl groups. Subsequent exposure to phosphine removes these methyl group protons, leaving various, as yet not fully characterised, phosphorus species. Exposure to phosphine does not appear to regenerate the acid sites on the zeolite.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The surface composition of various ceramic substrates used for electronics applications is heterogeneous. In the case of debased alumina, this may result from the diffusion of sintering aids such as silica, added during the manufacturing process, which produce a complex bonding surface. In this study, the durability of a visible light curing resin applied to a variety of ceramic substrates of differing acidity/basicity was investigated. Butt-joints consisting of photocured resin adhered to quartz, silicon wafers and polished alumina were produced. Following immersion in water at 50°C for periods of several weeks, joints were fractured (in situ in the VG ESCALAB Mk II and just prior to loading into the Scienta ESCA300). Angle-resolved XPS analysis was carried out on both sides of the failure. Failure occurred cohesively, with 1-2 nm of polymer remaining on the ceramic side of the failure. Orientation of the oxygenated functional groups of the polymer was observed within this overlayer, with methoxy groups being aggregated immediately adjacent to the inorganic surface; subtle differences were observed between the polished alumina and other substrates. An absence of the aromatic groups from the photocured polymer was also noted on the ceramic side of the failure. These results are explained in terms of acid-base interactions, and a model for adhesion and subsequent failure of the system is proposed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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