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Volume 42 (1994)
- Issue 6 Pages 291-
- Issue 5 Pages 249-
- Issue 4 Pages 225-
- Issue 3 Pages 155-
- Issue 2 Pages 67-
- Issue 1 Pages 1-
Volume 42, Issue 2
Displaying 1-4 of 4 articles from this issue
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REVIEW
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Itsuo KATAKUSE1994 Volume 42 Issue 2 Pages 67-93
Published: 1994
Released on J-STAGE: July 20, 2007
JOURNAL FREE ACCESSThe sputtering technique is an useful method for investigating clusters. Positive and negative clusters are produced from solid samples by bombardment of energetic Xe ions. As the clusters have high internal energies, it is suitable for the study on dissociation mechanism. This article describes sputter ion source, detection system for very heavy clusters, characteristics of metallic and rock salt type clusters produced by sputtering, rare gas clusters from bubbles and transition from van der Waals to metallic clusters. In the chapter of metallic clusters, energy levels in a square well potential, electronic shell structures of Au, Ag, Cu, Zn, Cd, Hg, and Al clusters, dissociation of doubly charged silver clusters and super shell structure of Na and Hg clusters are described. The characteristics of rock salt type clusters, CsI and MgO are shown in chapter 5. Rare gas clusters were detected by bombarding on Al metals. When bubbles in the metal were destroyed by farther bombard, they are produced. Transition from van der Waals to metallic clusters was observed in (Hg)nCs+ and (Mn)n+ clusters.View full abstractDownload PDF (1626K)
REGULAR PAPERS
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Masayoshi KUBO, Kazuaki KANO, Koji HAYASHI, Masao MARUNO, Philip IRELA ...1994 Volume 42 Issue 2 Pages 95-103
Published: 1994
Released on J-STAGE: July 20, 2007
JOURNAL FREE ACCESSDespite the standard ionization techniqus. EI, CI, FAB, etc., there is still a continuing analytical utility for Field Desorption (FD) for certain classes of compounds. Therefore, the method of accurate mass measurement by FD Peak Matching was investigated. Recent advances in instrument control and data acquisition/processing (post-acquisition data processing) with the engineering workstation have enabled accurate mass measurement to become a viable option for routine analysis.
Molecular masses of thirteen standard compounds were measured by the FD Peak Matching to illustrate the applicability of this method. Generally, both sample and reference, PEG400 or PEG600, were loaded onto the same emitter. The possibility of using separate emitters for sample and reference was also explored.
The accuracy obtained was comparable to other routine methods (e.g., EI, FAB). Six important factors which enable accurate mass measurement to be done on a routine basis were elucidated by this investigation.View full abstractDownload PDF (488K) -
Hiromi YAMAZAKI, Makoto TSUNEDA, Yasusi TAKAKUWA, Yoshihisa HONDA, Ats ...1994 Volume 42 Issue 2 Pages 105-115
Published: 1994
Released on J-STAGE: July 20, 2007
JOURNAL FREE ACCESSBecause the resolution of Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometers is inversely proportional to the mass of ion, they are particularly suited to the analysis of low mass samples. For this purpose the magnetic field generated by permanent magnets is adequate. The spectrometer using a permanent magnet has the advantages of low cost, compact size and easy operation and maintenance. These features have motivated us to develope a new FT-ICR spectrometer with a permanent magnet which can determine chemical composition of samples by precise mass measurement. The magnet is made of rare-earth compound and the magnetic circuit is designed to be compact and to generate a highly homogeneous magnetic field. The spectrometer can be easily operated with a track-ball and a ten-key board. Mass resolution of 104-105 is obtained in the normal operating conditions. It is shown that the spectrometer can analyse the composition of gases having the same mass numbers such as CO/N2/C2H4, CO2/N2O and He/D2. The spectrometer will be useful for industrial applications like process and medical analyses.View full abstractDownload PDF (765K)
NOTE
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Atsushi SHIGIHARA, Mitsuo TAKAYAMA1994 Volume 42 Issue 2 Pages 117-122
Published: 1994
Released on J-STAGE: July 20, 2007
JOURNAL FREE ACCESSThe fragmentation mechanism for isobutene loss from the protonated molecules [M+H]+ of 6- and 8-prenylated chromanones as the model compounds for 6- and 8-prenylated flavonoids was examined by using the MNDO-PM3 method. Heats of formation of the [M+H]+ ions and energy barrier of the fragmentation were estimated. The calculated results rationalized the fact that 6-prenylated flavonoids always show extensive loss of the isobutene from the [M+H]+ ion more than the corresponding 8-prenylated flavonoids in their fast-atom bombardment (FAB) spectra. The point is that the proton migration occur through intramolecular hydrogen bonding with low energy barrier prior to the loss of isobutene.View full abstractDownload PDF (317K)
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