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  • Artikel: DFG Deutsche Nationallizenzen  (8)
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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 7256-7263 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: One-dimensional reactive-flow simulations of a hot-filament chemical vapor deposition-system including surface reactions of H atoms and H2 molecules are reported. The corresponding governing equations of mass, momentum, chemical species, and energy are solved assuming a stagnation-point flow. In the model, the filament is catalytically active to dissociate H2 molecules, and the net surface reaction is the recombination of H atoms to H2 molecules. It is shown that the surface chemistry strongly influences the H and CH4 concentration profiles, whereas only a minor influence on CH3 and C2H2 concentrations—possible candidates as precursors for diamond growth—is observed. The influence of the surface temperature on gas-phase species concentration is discussed. At surface temperatures below 1000 K, the CH3-concentration dependence on the substrate temperature can be characterized by an activation energy of 14 kJ/mol which is in good agreement with experiment. The simulations show that this activation energy is a pure gas-phase effect due to recombination of methyl radicals and H atoms to methane in the cool gas layer near the substrate. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 255 (1977), S. 1024-1024 
    ISSN: 1435-1536
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 256 (1978), S. 1150-1150 
    ISSN: 1435-1536
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Catalysis letters 61 (1999), S. 15-25 
    ISSN: 1572-879X
    Schlagwort(e): oxygen‐free methane conversion ; platinum ; carbon layer ; catalysis ; hydrocarbon surface kinetics ; modeling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract In many metal‐catalyzed conversion processes of hydrocarbons at atmospheric pressure a carbonaceous overlayer quickly builds up at the catalyst covering nearly the whole surface. However, the metal still remains catalytically active. Several models have been proposed over the years to explain the crucial role of the carbonaceous overlayer during the conversion of hydrocarbons. The model presented here contemplates adsorbate effects, which means that surface carbon modifies the dehydrogenation activity of Pt. A hydrocarbon reaction mechanism on platinum, including C1 and C2 species, is established. The mechanism is based on elementary reactions offering the opportunity of using the same mechanism for a wide range of applications. It is also applied to extended simulations of higher pressures and smaller flow velocities revealing increased C2H6 yields under these conditions.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 37 (1985), S. 189-195 
    ISSN: 1432-0649
    Schlagwort(e): 82.50 ; 42.60
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract O2/O3 mixtures are ignited by absorption of laser pulses of a TEA CO2 laser along the axis of a cylindrical cell. The dependence of the radial propagation of the O3 decomposition, detected by uv absorption of the ozone, on laser fluence and on O3 concentration is investigated. Oscillations of the signals are identified to be the first radial acoustic mode of the cell. For mixtures of 0.35 bar and 0.70 bar total pressure and O3 percentages within 20–50%, the ignition limit is in the order of 0.1–0.2 J/cm3 (absorbed energy density). These values are in reasonable agreement with the results of the corresponding numerical simulations.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 255 (1977), S. 704-705 
    ISSN: 1435-1536
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 255 (1977), S. 704-704 
    ISSN: 1435-1536
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 2 (1970), S. 457-473 
    ISSN: 0538-8068
    Schlagwort(e): Chemistry ; Physics Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of nitrogen atoms with methylacetylene has been studied using a fast-flow low-pressure reactor coupled to a mass spctrometer by a nozzle-beam sampling system. Hydrogen atom concentrations were measured by ESR analysis. Experimental second-order rate constants for the consumption of N atoms, of C3H4, and for the formation of N2 were determined in the temperature range of 283° to 485°K. Product profiles of all stable species and of hydrogen atoms and methyl radicals were obtained for different initial concentrations of the reactants. Two different reaction pathways can be distinguished: one provides for recombination of N atoms, and the second leads to the formation of cyano compounds and other hydrocarbons. Only the latter process is influenced by the addition of hydrogen atoms. Mechanisms for the two pathways are discussed.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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