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 44, Issue 4
Displaying 1-4 of 4 articles from this issue
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REGULAR PAPERS
  • Enhancement of Lyman-α Emission for Detection of Diffracted Atomic Hydrogen Beams
    Kohichi KOTAKI, Tatsuo ARIKAWA
    1996 Volume 44 Issue 4 Pages 461-472
    Published: 1996
    Released on J-STAGE: July 20, 2007
    DOIhttps://doi.org/10.5702/massspec.44.461
    JOURNAL FREE ACCESS
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    An attempt was made to enhance the Lyman-α emission for the detection of low energy atomic hydrogen beams diffracted from the surface by means of (1+2) resonantly enhanced multiphoton ionization (REMPI). Employing a Kr-Ar mixing cell, the efficiency of frequency tripling to generate the vacuum ultraviolet (VUV) emission around the Lyman α line was fairly enhanced by about one order of magnitude compared to that with an ordinary pure Kr cell. An ionization chamber filled with acetone was also investigated for the detection and monitoring of the VUV light. Monochromatic atomic hydrogen (H) beams were prepared either via photodissociation of hydrogen-bromine (HBr) molecules at 243 nm with de Broglie wavelengths of 0.31Å and 0.25Å, or via photodissociation of hydrogen-iodine (HI) molecules at 266 nm with de Broglie wavelengths of 0.35Å an 0.23Å, respectively. Employing these H-beams, feasibilities for detection and visualization of diffraction patterns from the surface by the use of a fast optical imaging system were investigated by means of computer simulation experiments.
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  • Formation of [M - H]+ Ions under Fast Atom Bombardment Conditions: Trolox and α-Tocopherol
    Mitsuo TAKAYAMA, Toshiyuki KOSAKA, Takeshi KINOSHITA
    1996 Volume 44 Issue 4 Pages 473-481
    Published: 1996
    Released on J-STAGE: July 20, 2007
    DOIhttps://doi.org/10.5702/massspec.44.473
    JOURNAL FREE ACCESS
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    Formation of the [M-H]+ ions of Trolox and α-tocopherol produced under fast atom bombardment (FAB) conditions has been examined by using collision-induced dissociation (CID) technique with tandem mass spectrometry. The CID spectra of the [M-H]+ ions of these compounds have been compared with those of the M+· and [M+H]+ ions. The CID spectra of the [M-H]+, M+·, and [M+H]+ ions of Trolox showed characteristic ion peaks at m/z 163, 164, and 165, respectively, whereas the CID spectra of the [M-H]+, M+·, and [M+H]+ ions of α-tocopherol showed a common peak at m/z 165 which comes from an intramolecular hydrogen rearrangement reaction, despite a common structure unit corresponding to those fragment ions. In order to explain the results obtained, possible structures of the [M-H]+ ions of Trolox and α-tocopherol would be presented though the site(s) of a hydrogen loss from analytes could not be determined. The structure characteristics of analytes and the mechanism to form [M-H]+ ions under matrix FAB conditions have been discussed, and it has been concluded that the formation of molecular-related ions [M-H]+, M+·, and [M+H]+ occurs competitively according to the nature of analyte and matrix molecules under matrix FAB conditions.
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  • Effects of Additives to Methyl Hydroperoxyoleates on the Formation of Protonated Molecules and/or Molecular Adduct Ions in Liquid Ionization Mass Spectrometry
    Yukio YOKOYAMA, Yoshiyuki MOCHIDA, Toshinaga KAWAI, Shigeo NAKAMURA, M ...
    1996 Volume 44 Issue 4 Pages 483-491
    Published: 1996
    Released on J-STAGE: July 20, 2007
    DOIhttps://doi.org/10.5702/massspec.44.483
    JOURNAL FREE ACCESS
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    Effects of additives, introduced to a sample through vapor phase, on the formation of protonated molecules and/or molecular adduct ions were investigated in liquid ionization mass spectrometry for the analysis of methyl hydroperoxyoleates. Water and formic acid having small proton affinities were useful for increasing ion abundance of protonated molecules [M+H]+. 2-Aminoethanol and pyridine having slightly greater proton affinities were useful for forming molecular adduct ions [M+H+L]+ (L: additive molecule). The use of additives, acting as matrix for producing [M+H]+ and/or as reagent for forming [M+H+L]+ in liquid ionization mass spectrometry, provided useful mass spectral characteristics of the molecular weight and structure of unknown compounds.
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NOTE
  • Criterion for the Choice of Matrix in Fast Atom Bombardment Mass Spectrometry
    Mitsuo TAKAYAMA, Toshie TAKAHASHI
    1996 Volume 44 Issue 4 Pages 493-497
    Published: 1996
    Released on J-STAGE: July 20, 2007
    DOIhttps://doi.org/10.5702/massspec.44.493
    JOURNAL FREE ACCESS
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    A criterion for the choice of liquid matrix in fast atom bombardment mass spectrometry (FAB-MS) has been presented. The results obtained from the criterion indicated that suitable matrices for positive-ion FAB are thioglycerol (TG), dithiothreitol (DTT), and m-nitrobenzyl alcohol (NBA) and those for negative-ion FAB are triethanolamine (TEA) and diethanolamine (DEA). Further, the criterion proposed that glycerol (G) is a suitable matrix material for both positive and negative-ion modes. These indications were in good agreement with the empirical facts.
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