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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Plasma chemistry and plasma processing 8 (1988), S. 263-280 
    ISSN: 1572-8986
    Keywords: Microwave plasma ; gas-phase reactions ; mass spectrometer sampling ; discharge chemistry of SF6 with O2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Processes which occur in microwave discharges of dilute mixtures of SF6 and O2 in He have been examined using a flow reactor sampled by a mass spectrometer. Two classes of experiments were performed. In the first set of experiments, mixtures containing 6×1011 cm−3 SF6, 6×1016 cm−3 He, and O2 in the range (0–3.6)×1013 cm−3 were passed through a 20-W 2450-MHz microwave discharge. The gas mixtures arriving at a sample point downstream from the discharge were examined for SF6, SF4, SOF2, SOF4, SO2F2, SO2, F, and O. In the second class of experiments, rate coefficients were measured for the reactions of SF4 with O and O2 and for the reaction of SF with O. The rate coefficient for the reaction of SF with O was found to be (4.2±1.5)×10−11 cm−3 s−1. SF4 was found to react so slowly with both oxygen atoms and oxygen molecules that only upper limits could be placed on the rate coefficients for these reactions. These values were 2×10−14 cm3 s−1 and 5×10−15 cm3 s−1 for reactions with O and O2 respectively. The observed distribution of products from the discharged mixtures is discussed in terms of the measured rate coefficients.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Plasma chemistry and plasma processing 8 (1988), S. 281-291 
    ISSN: 1572-8986
    Keywords: Microwave discharge ; reaction rates ; mass spectrometer sampling ; discharge chemistry of SF6
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Reactions of both SF4 and SF5 with F have been studied at 295 K in a gas-flow reactor sampled by a mass spectrometer. The rate coefficient for the combination reaction of F with SF4 to produce SF5 was found to increase from (0.9 to 3.0)×10−12 cm3 s−1 when the helium bath gas number density was increased from (2 to 26)×1016 cm−3. The values obtained here are three orders of magnitude higher than a recent estimate of the high-pressure value based on the modelling of photochemical studies. The experimental results have been compared with RRKM and master equation calculations in which a simplified Gorin model has been used to determine the structure of the transition state. These calculations show that reasonable agreement can be obtained between the experimental data and the calculation if a small (∼2 KJ/mol) activation energy is assumed. The rate coefficient for the reaction between SF5 and F to produce SF6 was found to be independent of helium bath gas number density within the range given above. The value obtained for the rate coefficient was 9×10−12 cm3 s−1 with an uncertainty of a factor of 2. This value is close to that of 1×10−11 cm3 s−1 computed from the simplified Gorin model and to the value of 1.7×10−11 cm3 s−1 deduced from modelling of photochemical experiments.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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