Shinku
Online ISSN : 1880-9413
Print ISSN : 0559-8516
ISSN-L : 0559-8516
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Volume 15, Issue 8
Displaying 1-3 of 3 articles from this issue
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  • On the Applications of Vacuum Technology to the Manufacturing or Developing Superconducting Materials
    Akira KONO
    1972 Volume 15 Issue 8 Pages 276-282
    Published: August 20, 1972
    Released on J-STAGE: September 29, 2009
    DOIhttps://doi.org/10.3131/jvsj.15.276
    JOURNAL FREE ACCESS
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  • A New Method for the Measurement of Very Low Partial Pressures
    Hiroshi MIYAKE, Masami MICHIJIMA
    1972 Volume 15 Issue 8 Pages 283-291
    Published: August 20, 1972
    Released on J-STAGE: September 29, 2009
    DOIhttps://doi.org/10.3131/jvsj.15.283
    JOURNAL FREE ACCESS
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    Partial pressures below 10-15 Torr were measured with recurrent multi-channel scaling of ion current synchronized with the scanning of the analyzer magnet current. Mass spectra of residual gases at total pressures below 1×10-9 Torr were recorded for wide mass ranges with resolutions of better than 110. The method minimized the effect of the time variation of ion counting efficiency for long counting intervals of more than 100 hours and made it possible to measure an ion current below 10-20 A with high reliability. The false peaks formed by accidental bursts of noise pulses were easily discriminated in the computer-programmed calculation of partial pressures. An Allen-type secondary electron multiplier of 12 stage Cu-Be dynodes connected to a low-noise charge-sensitive preamplifier was used for detecting single ions of which energies were less than 4 keV. Pulse height distributions for various residual gas ions were studied to determine a suitable pulse height discriminating level to give optimum signal to noise ratio.
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  • Chemisorption Phenomena of Oxygen and Hydrogen on Tin Oxide Powders
    Yusuke MIZOKAWA, Shogo NAKAMURA
    1972 Volume 15 Issue 8 Pages 292-303
    Published: August 20, 1972
    Released on J-STAGE: January 28, 2010
    DOIhttps://doi.org/10.3131/jvsj.15.292
    JOURNAL FREE ACCESS
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    Tin oxide is a non-stoichiometric N-type semiconductor, and its electrical conductivity is largely influenced by the chemisorption of oxygen and hydrogen. We studied the chemisorption phenomena and its states by the variation of the electrical conductance, so that we first had to decide the conduction mechanism. The sample was composed of numerous crystallites and their surfaces were covered with the oxidized film, on which the negative oxygen ions were chemisorbed. Hence they formed the potential barriers for conduction. Oxygen chemisorption caused to not only reduce the carriers but also increase the hight of potential barrier. On the contrary, hydrogen chemisorption caused to increase the carriers, reducing the barrier height. Therefore, both the electrical conductance and the chemisorption velocity were largely influenced by the chemisorption, even if the coverage was very small. Moreover, the heat of adsorption influenced the electrical conductance, especially at high temperatures.
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