巻号一覧
39 巻 (1991)
- 6 号 p. 301-
- 5 号 p. 213-
- 4 号 p. 183-
- 2 号 p. 49-
- 1 号 p. 1-
39 巻, 5 号
選択された号の論文の8件中1～8を表示しています
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藤原 真, 三浦 健児, 井上 雅夫1991 年 39 巻 5 号 p. 213-223
発行日: 1991年
公開日: 2007/07/20
ジャーナル フリーEffects of the three cyclotron resonance excitation waveforms on the trapping oscillation (z-motion) of ions confined in a cylindrical Fourier transform ion cyclotron resonance (FT-ICR) cell are examined by computer simulation of ion trajectories.
As to the fast frequency sweep waveform, ion signal intensity varies with the direction of the frequency sweep: by upward sweeping the amplitude of z-motion is increased at frequencies slightly higher than the cyclotron resonance frequency and by downward sweeping the z-motion is damped at slightly lower frequencies. Thus the down-sweep is suitable for ICR signal detection and for ion ejection the up-sweep is preferable.
In regard to the stored waveform inverse Fourier transform (SWIFT) waveform, the z-motion varies with the modulation of phase with frequency. In the case of the quadratic phase modulation, where ions are successively excited from low to high masses, the motion of ions in the z-direction is similar to that observed with the down-sweep excitation waveform.
Because of the extremely short duration of the impulse waveform it might be thought that the waveform hardly has time to excite the z-motion. However, the displacement of ion position by the strong electric field activates the z-motion after the impulse, and the ions are eventually ejected towards the trapping electrodes of the cell.
Influence of the DC potential applied to the trapping electrodes on z-motion is studied with the down-sweep excitation experiments. The threshold amplitude of the excitation waveform at which ions are ejected to the trapping electrodes increases with the DC trapping voltage. At a trapping voltage above a certain amplitude the ions are no longer ejected and the radii of the cyclotron orbits continually increase with excitation amplitude so that they collide with the inner surface of the cylindrical electrodes and are neutralized and lost.
A method is proposed for deterring the z-motion by applying an AC potential at a frequency twice the frequency of trapping oscillation of ions to the trapping electrodes. Effectiveness of the method is confirmed by trajectory calculation.抄録全体を表示PDF形式でダウンロード (785K) -
横田 佳子, 竹内 孝江, 山本 正夫1991 年 39 巻 5 号 p. 225-233
発行日: 1991年
公開日: 2007/07/20
ジャーナル フリーWe have studied the fragmentation of four alkylsilanes (CH3SiH2C3H7, (CH3)2SiHC3H7, (CH3)3SiC3H7, CH3SiH2C5H11) under EIMS. The characteristic ions of [M-H]+, [M-H2]+·, m/z 73 and m/z 45 appeared from methylpropylsilane and methylpentylsilane in a similar manner as the fragmentation of butylmethylsilane reported in a previous paper. From the results of deuterium labelled compounds it was confirmed that [M-H]+ is produced by eliminating an H-atom on Si-atom. It was also suggested that [M-H2]+· is produced by eliminating two H-atoms on Si-atom with the H/D scrambling. The ion of m/z 73 is stabilized by σ-π conjugation. The ion of m/z 45 is mainly formed as the secondary scission ion. By replacing an H-atom with a methyl group on Si-atom the mass spectra of the resulting alkylsilanes become similar to those of the corresponding alkanes.抄録全体を表示PDF形式でダウンロード (457K) -
Hisao NAKATA, Akemi TANAKA1991 年 39 巻 5 号 p. 235-238
発行日: 1991年
公開日: 2007/07/20
ジャーナル フリーIn order to demonstrate the validity of the protonation susceptibility of pertinent functional groups, the chemical ionization mass spectra were measured for bifunctional aromatic compounds of the type p-XCH2-C6H4-CH2Y, where X=OH and NH2, Y=OCH3 and N(CH3)2. The relative protonation susceptibilities obtained from the observed spectral data are in good agreement with those available from other pairs of compounds reported previously. The order of the susceptibilities is not even qualitatively parallel to that of the proton affinities of these functional groups, and the result therefore indicates the protonation susceptibility being a significant and useful parameter in interpreting the chemical ionization mass spectra.抄録全体を表示PDF形式でダウンロード (268K) -
Hisao WUSHIKI1991 年 39 巻 5 号 p. 239-250
発行日: 1991年
公開日: 2007/07/20
ジャーナル フリーRain waters from three regions of South Arabia were analyzed for 18O/16O and D/H. Appreciably enriched isotopic compositions were found from every region. The evaporation effect on the rain drops was not found to be major cause because the rains are plotted considerably in parallel with the Craig's meteoric water line. The parallelism prevails up to certain enriched level usually exceeding SMOW in δ18O vs. δD diagram. Instead the causes of the isotopic enrichment were ascribed to the large difference in evaporation and condensation temperature and/or to the proximity between vapor forming sea area and the high mountains, i.e., the most probable area for rain formation under the forced air lifting in arid region. The depletion of heavy isotopes in the deep-born groundwater of old age indicates a different climate system to have prevailed in the past. Should “Global Warming” proceed, the intensified south-west Indian monsoon in summer may create isotopically enriched terrestrial waters in dominance.抄録全体を表示PDF形式でダウンロード (627K) -
Naohiro YOSHIDA, Takahiro YONEGUCHI, Manabu KITANO1991 年 39 巻 5 号 p. 251-259
発行日: 1991年
公開日: 2007/07/20
ジャーナル フリーA method to determine stable isotope ratios of atmospheric water vapor and carbon dioxide is presented. Simplified sampling and careful purification allow precise determination of isotope ratios. Air sample is collected in a plastic bag. The water vapor and carbon dioxide are recovered by pumping through cryogenic traps under atmospheric pressure. Hydrogen and oxygen isotope ratios are determined for small amount of atmospheric water vapor. Carbon and oxygen isotope ratios are determined for carbon dioxide purified from nitrous oxide. The analytical errors of the present method are practically similar to those of conventional methods.抄録全体を表示PDF形式でダウンロード (631K) -
Atsuko SUGIMOTO, Xu HONG, Eitaro WADA1991 年 39 巻 5 号 p. 261-266
発行日: 1991年
公開日: 2007/07/20
ジャーナル フリーA combined gas chromatography/combustion/isotope ratio mass spectrometer (GC/C/IRMS) system was employed to develop a rapid and simple method for measuring δ13C of bubble methane collected from wetlands. In spite of incomplete combustion of methane to CO2, calibration using standard methane can provide reproducible data with accuracy of ±0.5‰. Duplicate analyses of two gaseous samples were successfully measured within 20 min.抄録全体を表示PDF形式でダウンロード (401K) -
Tadakatsu YONEYAMA, Takashi UCHIYAMA, Jinya YAZAKI1991 年 39 巻 5 号 p. 267-276
発行日: 1991年
公開日: 2007/07/20
ジャーナル フリーNitrogen accumulation and changes in natural 15N abundance (δ15N) in five pea cultivars and two faba bean cultivars were investigated in an alluvial soil in the field during winter and spring. The amounts of nitrogen accumulated in tops were 16 to 20 g m-2 in pea plants, and 17 and 24 g m-2 in faba bean at final harvest. About 67~97% of the nitrogen in pea plants and 79 and 86% in faba bean were derived from atmospheric N2 based on the difference of δ15N values between N2-fixing legumes and the reference plant (barley was used).
The nodules in most of the pea, faba bean, and vetch plants were enriched in 15N (up to +8‰). The 15N enrichment was more obvious in mature and senescent nodules, and the soluble N fraction of the nodule cytosol was most highly enriched in 15N. The δ15N values of ammonia extracted from the nodule bacteroids were higher than those of the organic N in this organelle and of ammonia in the nodule cytosol. The mechanisms of 15N enrichment in nodules were discussed.抄録全体を表示PDF形式でダウンロード (680K) -
Takahito YOSHIOKA1991 年 39 巻 5 号 p. 277-281
発行日: 1991年
公開日: 2007/07/20
ジャーナル フリーThe carbon and nitrogen isotope ratios of Hypomesus transpacificus (a pond smelt) in a eutrophic lake, Lake Suwa, were measured from April to September in 1986 and 1987. The differences in the isotope ratios between these two years were observed. The stable isotopes were transferred from phytoplankton to zooplankton and pond smelt, associated with organic matters. Therefore, the difference in the isotope ratios in two years seemed to reflect the differences of the proceeding of primary production. It ws suggested that the carbon and nitrogen isotope ratios of animal, whose trophic level is far from primary producer, can be the qualitative indicators for assessing the primary production in a lake ecosystem.抄録全体を表示PDF形式でダウンロード (401K)
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