Journal of the Mass Spectrometry Society of Japan
Online ISSN : 1880-4225
Print ISSN : 1340-8097
ISSN-L : 1340-8097
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Volume 35, Issue 4
Displaying 1-4 of 4 articles from this issue
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REGULAR PAPERS
  • Function Analyses of the Time-of-Flight Mass Spectrometer with an Electrostatic Reflector:
    Applications for SIMS and SNMS
    Makoto Kato, Akinori Mogami, Motohiro Naito
    1987 Volume 35 Issue 4 Pages 186-200
    Published: 1987
    Released on J-STAGE: May 01, 2007
    DOIhttps://doi.org/10.5702/massspec.35.186
    JOURNAL FREE ACCESS
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    The mass resolution of a time-of-flight mass spectrometer (TOFMS) with a two-stage electrostatic reflector is calculated for SIMS and SNMS (Secondary lon, and Secondary Neutral Mass Spectrometry) applications. The parameters in reflector operation are optimized to satisfy the time focusing conditions, where the flight time spread in an accerelation region is also taken into account. The calculation method used is a numerical one, as well as an analytical one for a second order time focusing.
    The main factors which limit the resolution in SIMS are (i) the time spread ΔT due to the energy spread ΔE of secondary ions and (ii) the uncertainty in the time-of-flight Δτ caused by the primary ion beam and the signal detecting system. Although the time spread ΔT can be reduced by increasing the acceleration voltage Ua, excessively high Ua reduced the total flight time and therefore the resolution. The resolution attains a maximum value of nearly 10,000 at the accerelation voltage of 100V for ΔE=10eV, Δτ=5ns and a 2m total drift length.
    In the case of SNMS, not only ΔE but also the spatial width Δs of an ionizing laser beam affects the time spread ΔT. However, the effect of Δs can be partially compensated by applying a mild accerelation voltage to the ionizing region. The maximum value of resolution is about 1,000 at the total accerelation voltage of 1,000V for ΔE=10eV, Δs=1.0mm and Δτ=10ns.
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  • Effects of Stereoisomerisms on the Electron Ionization Mass Spectra and the IKE Spectra of Cinchona Alkaloids
    Hidetoshi Fujiwara, Akira Kato, Ichizo Okabayashi
    1987 Volume 35 Issue 4 Pages 202-209
    Published: 1987
    Released on J-STAGE: May 01, 2007
    DOIhttps://doi.org/10.5702/massspec.35.202
    JOURNAL FREE ACCESS
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    The mass spectra of two sets of stereoisomers possessing a quinuclidine base skeleton (quinine, quinidine, cinchonine and cinchonidine) were compared. All of the epimers have characteristically different electron ionization spectra. Similar differences were also found in the ion kinetic energy spectra. The main effects of stereoisomers on the abundance ratio clearly indicated the occurrence of some highly stereospecific or stereoselective decomposition processes. Conclusion concerning the mechanisms of these reactions, based on the normal and metastable ion spectra for the epimers, was also drawn.
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TECHNICAL REPORT
  • High Sensitive Detector for Positive and Negative Ions Uing Post-acceleration
    Toshio Ichihara, Itsuo Katakuse
    1987 Volume 35 Issue 4 Pages 216-220
    Published: 1987
    Released on J-STAGE: May 01, 2007
    DOIhttps://doi.org/10.5702/massspec.35.216
    JOURNAL FREE ACCESS
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    A high sensitive detection system for heavy ions of low energy was described. In order to improve the conversion efficiency from positive or negative heavy ions, to electrons at the conversion dynode of the electron multiplier, the whole assembly of detection sysytem (electron multiplier, d. c. amplifier, high voltage power supply for the electron multiplier and power supply for the d. c. amplifier and A-D converter) were isolated from the ground and were kept at -10kV potential for the positive ion detection and +10kV for the negative ion detection. The d. c. signal from the d. c. amplifier was converted to 12-bits digital signal by the A-D converter and was sent to the ground side by light-emitting-diodes (LED). It was received by photo-transistors and converted back to a d. c. signal by a D-A converter. The conversion cycle of the A-D converter was 8 μsec. With this detection sysytem, the high sensitivity for negative heavy ions was obtained.
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