Development of Analytical Ion Microscope and Measurement of Isotopic Variations of Light Elements in Meteorites

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Mechanical set-up and arrangement of ION MICROSCOPE, which has been designed and developed for the last four years, have been completed. A high voltage power supply for the discharge of producing primary ions was also constructed. Furthermore, it was tested if main and scanning power supply for the electromagnet of mass spectrometer were clearly worked. As a result of the test mentioned above, these powers supplies were found to be effectively used for the magnetic scanning of the mass spectrometer. In addition to these, two pumping systems of turbo-molecular and oil rotary pumps were added to evacuate the ion ilicroscope chamber. 2 X 10^<-6> Pa was achieved by the pumping. Primary ion source was repaired so as to avoid the discharge between a ground potential part and a high voltage part. By this repair, unexpected discharge in the primary ion source chamber could be avoided and steady primary ions were produced. The detection current of the primary ions which was detected at the first drawing-out electrode to be about 40 muA. The construction of this ION MICROSCOPE was roughly completed.For the isotopic analysis of iron, laboratory standard of isotopic abundances of iron were determined with high accuracy. Hitachi IMA-2A ion microprobe analyzer of Osaka University was used for this analysis. The abundances were determined as listed in the following. ^<54>Fe= 5.7238<plus-minus>0.0015%, ^<56>Fe= 91.8545<plus-minus>0.0014%, ^<57>Fe= 2.1470<plus-minus>0.0005%, ^<58>Fe= 0.2746<plus-minus>0.0003%.