Microprobe chemical state analysis of light elements in earth and planetary materials.

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After the investigation for three years, the following results have been obtained.(1) Construction of the experimental system.We have installed a new X-ray fluorescence detector at BL-8B of Photon Factory, High Energy Institute of Physics. The detector has three Si (Li) sindows suitable for light element analysis. We have optimized the system so as to study the chemical speciation of light elements in earth and planetary minerals. The instrumental system is now open to public use at the Photon Factory.(2) Chemical state analysis of Ti, Cr and Fe in meteorites by XRF microprobe.Chemical speciation of transition elements in meteorites was made using focused X-ray microbeam (minimum size ca.10 mum). Chemical state mapping based on the XANES and SIXES techniques produced isolated maps of Fe^<2+> and Fe^<3+> ions in a sample of pseudomorph of goethite after pyrite. Chemical forms of Cr and Ti were dominantly trivalent and tetravalent in the chondrules of in Allende, Krymka, Semarkona, and Y … More amato-691 meteorites, respectively, shile additional Cr^<2+> and Ti^<3+> componenets appear to be present in the chondrule of Yamato-691 meteorite.(3) Two dimensional chemical state mapping of sulfur in geological samples.Two dimensional analysis of a sedimentary rock containing sulfur was carried out and compositional image of sulfate and sulfide ion was successfully obtained by changing the excitation energy. The result visualized the oxidation process of the rock sample by weathering.(4) Chemical state analysis of sulfur in sodalite group minerals.S K-edge XANES spectra of the sodalite group minerals exhibited characteristic chemical shifts, as well as unique spectral shapes. The spectra of hauyne and helvite exhibited typical peaks of sulfate ions and sulfide ions, respectively. Although the spectrum of lazurite showed the peaks of sulfide and sulfate sulfur, the ideal formula of lzaurite is reported as Na6Ca2 (AI,6Si6O24) S2. The existence of sulfate ion was first found by the present study. Less