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Volume 34 (1986)
- Issue 6 Pages 339-
- Issue 5 Pages 257-
- Issue 4 Pages 197-
- Issue 3 Pages 139-
- Issue 2 Pages 71-
- Issue 1 Pages 13-
Volume 34, Issue 5
Displaying 1-6 of 6 articles from this issue
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REGULAR PAPERS
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Ruben Oláh, István Cornides, Anna Gergely1986 Volume 34 Issue 5 Pages 257-266
Published: 1986
Released on J-STAGE: May 01, 2007
JOURNAL FREE ACCESSThe relative abundances of several MCn polycarbide molecular ions (with a metal atom M) formed in the vacuum spark have been measured. It has been found that the abundance distribution patterns -in the range of n = 1 to 14 or more- are similar to those of the Cn carbon molecules. In particular, this similarity is very close in the case of the LaCn+ and Cn+1+ ions on the one hand, and in the case of the SiCn+, BCn+ and Cn- ions, on the other. In view of these results the structure of the LaCn and Cn molecules may be regarded as nearly identical, while in the case of the SiCn and BCn polycarbides, M+-Cn- type polarized molecules are assumed.View full abstractDownload PDF (541K) -
Takae Takeuchi, Masao Yamamoto, Kichisuke Nishimoto1986 Volume 34 Issue 5 Pages 267-278
Published: 1986
Released on J-STAGE: May 01, 2007
JOURNAL FREE ACCESSIn order to elucidate the fragmentation mechanism of propylamine following the low energy electron bombardment, the potential energy curves have been calculated by means of ab initio MO methods (STO-3G/4-31G). The present study indicates that the fragmentation due to Cα-Cβ bond cleavage is the main process at the low energy.View full abstractDownload PDF (571K) -
Seiji Tobita, Kenichi Tonokura, Susumu Tajima1986 Volume 34 Issue 5 Pages 279-286
Published: 1986
Released on J-STAGE: May 01, 2007
JOURNAL FREE ACCESSThe eliminations of methanol (CH3OH) and formaldehyde (CH2O) molecules from the molecular ion of 1,2-dimethoxyethane have been investigated by using deuterium labelling technique and mass analyzed ion kinetic energy (MIKE) spectra. The MIKE spectra show that the structure of the resultant ion at m/z 58, [M-CH3OH]+., is identical with that of the molecular ion of methyl vinyl ether ([CH3OCH=CH2]+.), and that of the ion at m/z 60, [M-CH2O]+., is an oxonium type ion, [CH3O(H)CH2CH2.)]+. The hydrogen rearrangements associated with these reactions result in thermochemical stabilization in the product systems. The loss of CH3OH molecule is accompanied by a kinetic energy release (T0.5 = 101 meV) larger than that in the elimination of CH2O molecule (T0.5=17 meV). A significant isotope effect is observed in the methanol and formaldehyde losses from deuterated 1,2-dimethoxyethane CH3OCH2CD2OCD3 (2,5-dioxahexane-1,1,1,3,3-d5). These results are discussed along with mechanistic features of both reactions.View full abstractDownload PDF (477K) -
Mamoru Ohashi, Makoto Iijima, Kazuo Tsujimoto1986 Volume 34 Issue 5 Pages 287-292
Published: 1986
Released on J-STAGE: May 01, 2007
JOURNAL FREE ACCESSTo test the validity of Vestal's "thick sauce model" for evaporation of thermally unstable compounds under in-beam EI conditions, matrix effects on in-beam EIMS and SIMS of several quaternary ammonium salts (C+X-, 1 ~ 6) were examined. The relative abundance ratios were traced for [C+] and [C+-·R] as neat and in different matrices such as water, glycerol and triethanolamine both at 240°C and 300°C for each compound. It is expected that [C+]/[C+-·R] represents the ratio of directly evaporated intact quaternary ammonium ion to a tertiary amine ion which is mainly produced by thermal decomposition of the parent quaternary ammonium compound. The processes are thought to be competitive. A remarkable matrix effect was observed in the case of benzyldimethylphenylammonium chloride (3) measured in glycerol. It is recommended, in conclusion, to try measurements of in-beam EI spectra using a matrix such as glycerol for better spectra.View full abstractDownload PDF (256K) -
Hidetoshi Fujiwara, Keiko Ishikawa, Akira Kato1986 Volume 34 Issue 5 Pages 293-306
Published: 1986
Released on J-STAGE: May 01, 2007
JOURNAL FREE ACCESSThe mass spectra of 2-dimethylaminomethylcyclohexanols, their acetyl, their benzoyl and their cinnamoyl derivatives were measured by electron impact ionization.
The characteristic peak in the mass spectra of 2-dimethylaminomethylcyclohexanols and their ester derivatives is the fragment peak at m/z 58 which is the base peak. The structure of this fragment ion appears to be CH2=N+(CH3)2.
The fragmentation mechanisms were elucidated with the aid of deuterium labeling measurement, metastable ion measurement and high resolution mass spectral measurement.View full abstractDownload PDF (637K) -
Takemichi Nakamura, Hidemi Nagaki, Takeshi Kinoshita1986 Volume 34 Issue 5 Pages 307-319
Published: 1986
Released on J-STAGE: May 01, 2007
JOURNAL FREE ACCESSThe unambiguous amino acid sequence analysis of a cyclic decapeptide antibiotic, gramicidin S, was performed using the title method and a B2/E constant linked scanning technique. The methodolgy for the sequence analysis involves the structure determination by tandem mass spectrometry (MS/MS) of a small acylium ion containing two or three amino acid residues, and the stepwise extension of the analyzed sequence by use of a combination of MS/MS and linked scanning.View full abstractDownload PDF (531K)
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