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 37, Issue 2
Displaying 1-4 of 4 articles from this issue
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REGULAR PAPERS
  • Positron Mass Spectrometer Design using Crossed Electric and Magnetic Fields
    Sakuo Matsui, Hikaru Inoue, Hiromitsu Nakabushi, Toshihiro Ueda, Yasuk ...
    1989 Volume 37 Issue 2 Pages 97-107
    Published: 1989
    Released on J-STAGE: May 01, 2007
    DOIhttps://doi.org/10.5702/massspec.37.97
    JOURNAL FREE ACCESS
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    Method of comparing the positron mass with the electron mass by using crossed fields is discussed on the basis of the relativistic calculation to the second order. Remodeling of a high resolution magnetic β-ray spectrometer into a positron-electron mass spectrometer is proposed. The crossed fields in the β-ray spectrometer equipped with a pair of cylindrical electrodes gives the mass dispersion of 1.3 μm/ppm at the optical circle of 0.75 m radius. Simulated peak profiles are presented for the monochromatic source of electrons or positrons and the β-ray source that emits them simultaneously in the continuous distribution.
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  • Structural Study of Intermediate Ions by Kinetic Energy Release and Thermochemical Consideration: [C7H8N]+ Ions from Toluidine Derivatives
    Susumu Tajima, Kazuo Ogino, Seiji Tobita, Ikuo Sakai
    1989 Volume 37 Issue 2 Pages 109-116
    Published: 1989
    Released on J-STAGE: May 01, 2007
    DOIhttps://doi.org/10.5702/massspec.37.109
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    The structures of the decomposing intermediate ions, [C7H8N]+ generated from a variety of toluidine and aniline derivatives were examined with the aid of kinetic energy release (KER).
    Among these ions, [C7H8N]+ ions generated from o-, m-, and p-toluidines and from 2, 3-, 3, 4-, and 2,6-xylidines are assigned to aminotropylium ion (a). The ions from o-, m-, and p-ethylanilines are interpreted as the corresponding aminobenzyl ion (b). A methyliminocy-clohexadiene ion structure (c) is postulated for the intermediate ion from N-methyl-o-, m-, and p-toluidines. The ion from N-ethylaniline is elucidated to be anilinomethene ion (d).
    These are in agreement with the results for the non-decomposing (stable) [C7H8N]+ ions, which were obtained by experimental heats of formation.
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  • Mass Spectra of Alkylsilanes. 1. Ethylmethylsilane, Methylpropylsilane, Diethylsilane, and Butylmethylsilane
    Masao Yamamoto, Masae Horiguchi, Yoshiko Yokota, Motoko Tanaka, Takae ...
    1989 Volume 37 Issue 2 Pages 117-128
    Published: 1989
    Released on J-STAGE: May 01, 2007
    DOIhttps://doi.org/10.5702/massspec.37.117
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    We have studied the fragmentation of four lower alkylsilanes (CH3SiH2C2H5, CH3SiH2-C3 H7, (C2H5)2SiH2, CH3SiH2C4H9) appeared in EIMS. The main fragment ions of m/z 45 (CH3 SiH2+) of ethylmethylsilane and methylpropylsilane were produced by the cleavage of the Si-C bond on the longer alkyl chain side, respectively, and the large fragment ion of m/z 59 (C2H5 SiH2+) of diethylsilane was also produced by the cleavage of Si-C bond. The base peak of butylmethylsilane was m/z 73 (CH3SiH2CH2CH2+). The H-loss ions [M-H]+ and the H2-loss ions [M-H2]+ of CH3SiH2C2H5 and CH3SiH2C3H7 were very abundant, especially at low ionization energies. The optimized geometries of neutral molecules and molecular cations of methylpropylsilane and butylmethylsilane were calculated by using ab initio MO method. The Si-C bond on the larger alkyl group side of molecular cation was lengthened from 1.87Å to 2.17Å and the net charge on Si-atom was positive. This showed that the Si-C bond was easy to cleavage and the fragment containing Si-atom to have a positive charge.
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  • Studies on Fast Atom Bombardment(FAB), Electron Ionization (EI) and Chemical Ionization(CI) Mass Spectra of Prenylated Flavonoids
    Mitsuo Takayama, Toshio Fukai, Taro Nomura
    1989 Volume 37 Issue 2 Pages 129-140
    Published: 1989
    Released on J-STAGE: May 01, 2007
    DOIhttps://doi.org/10.5702/massspec.37.129
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    Positive ion FAB mass spectra of prenylated flavonoids were compared with the corresponding EI and CI mass spectra, and some fragment ions similar to those in the EI mass spectra and CI-like intense protonated molecules (M+H)+ were recognized. Major fragmentations in the EI and FAB mass spectra were discussed. It was concluded that FAB ionization possesses both features, EI-like hard ionization and CI-like soft ionization.
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