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Digitale Medien

Charged particle densities and kinetics in a radio-frequency SF6 plasma (1994)

Kono, A. ; Endo, M. ; Ohata, K. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 76 (1994), S. 7221-7230

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: Electron, negative ion, and positive ion densities in a capacitively-coupled radio-frequency (rf, 13.56 MHz) SF6 plasma have been investigated as functions of the pressure (30–700 mTorr) and rf power. The decay of the charged particle densities in the afterglow has also been studied to obtain information about their kinetics. The electron density was determined by using a microwave cavity resonance technique. Negative ions were detected by measuring the density of photodetached electrons produced by pulsed laser irradiation of the plasma. The positive ion density was obtained from Langmuir probe measurements. At a rf power of 0.13 W/cm2 and at low pressures ((approximately-less-than)100 mTorr) the positive ion density, which is virtually equal to the negative ion density, is found to be larger than the electron density by a factor of a few hundred; the ion/electron density ratio increases with increasing pressure to reach a value of a few thousand at high pressures. Wavelength-dependent photodetachment measurements indicate that the dominant contribution to the photodetachment signal at 266 nm comes from F−, but F− is a minor negative-ion species with respect to the density; that is, the photodetachment efficiency for the dominant negative ion species (supposed to be SF−5) is low. The recombination rate constant for F− (supposedly with SF+5) is suggested to be an order of magnitude larger than that for the dominant ion species, the latter being estimated to be slightly smaller than 10−7 cm3 s−1. © 1994 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.358003

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Digitale Medien

Inhibitory Action of CCK-OP on Rat Proximal Colon (1994)

KISHIMOTO, S. ; MACHINO, H. ; KOBAYASHI, H. ; [weitere]

Oxford, UK : Blackwell Publishing Ltd

Annals of the New York Academy of Sciences 713 (1994), S. 0

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ISSN: 1749-6632

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Allgemeine Naturwissenschaft

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1749-6632.1994.tb44109.x

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Digitale Medien

X-ray area detector based on CCD readout for diffraction study (abstract) : Proceedings of the 4th International conference on synchrotron radiation instrumentation (1992)

Amemiya, Y. ; Kishimoto, S. ; Suzuki, M. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Review of Scientific Instruments 63 (1992), S. 659-659

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ISSN: 1089-7623

Quelle: AIP Digital Archive

Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik

Notizen: An x-ray area detector based on charged coupled device (CCD) readout has been designed and constructed for diffraction studies. Incident x-rays are converted to visible photons by a phosphor screen [Y2O2S or CsI(Na)] which is attached via fiber optic to the input surface of the demagnifying image intensifier with a 4:1 demagnification. The intensified visible image created on the output phosphor screen of the image intensifier is viewed through a 1:1 optical lens system by the cooled CCD (Thomson:THX31156) which has 1024×1024 pixels (pixel size: 19 μm×19 μm). The detector system should have the following characteristics: active area: 100 mm in diameter, spatial resolution: 0.1 mm×0.1 mm, detective quantum efficiency (DQE): about 70% for 8 keV, dynamic range: more than 104, readout time: 4 s. Nonuniformity of response due to the image intensifier is corrected by software. The CCD is cooled to −30° to −40° to reduce the dark current. The background noise level of the detector system corresponds to less than 10 x-ray photons per pixel. Detailed hardware and software configuration and measured performance of the system will be described. The system will be applied to small-angle x-ray scattering (SAXS) and protein crystallography.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.1142682

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Digitale Medien

Effect of hydrogen on carbon deposition from carbon monoxide on nickel catalyst (1994)

Yoshida, N. ; Yamamoto, T. ; Minoguchi, F. ; [weitere]

Springer

Catalysis letters 23 (1994), S. 237-243

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ISSN: 1572-879X

Schlagwort(e): Carbon deposition ; hydrogen effect ; nickel

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Abstract The role of hydrogen in carbon deposition on Ni has been studied at H2/CO 〈 1 and 698 K by determining the respective rates of the carbon-forming reactions: (1) CO + H2 →-C + H2O and (2) 2CO → C + CO2. The steady-state rate of reaction (1) increases in proportion to H2 pressure. On the other hand, reaction (2) is facilitated by the addition of an extremely small amount of H2, so that the rate becomes about eight times that for pure CO but hardly varies as more H2 is added. Similarly, there is a great difference in catalytic activity for ethylene hydrogenation between spent catalysts obtained in the deposition with and without H2. These findings suggest that hydrogen, even in a small amount, makes free Ni surface area larger than for pure CO.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00811358

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Digitale Medien

Nuclear Resonant scattering experiments with synchrotron radiation at KEK (1992)

Kikuta, S. ; Yoda, Y. ; Hasegawa, Y. ; [weitere]

Springer

Hyperfine interactions 71 (1992), S. 1491-1494

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ISSN: 1572-9540

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: Abstract Experiments of nuclear Resonant scattering carried out at PF and TRISTAN-AR of KEK are described, which include nuclear Bragg scattering in time domain as well as energy domain, time-resolved nuclear resonant forward scattering, and interferometric studies.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02397365

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