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

经过三年的调查，得到了以下结果：(1)实验体系建设。我们在高能物理研究所光子工厂BL-8B安装了一台新的x射线荧光探测器。探测器有三个硅（锂）窗口，适合于轻元素分析。为了研究地球和行星矿物中轻元素的化学形态，我们对该系统进行了优化。该仪器系统现已在光子工厂向公众开放使用。(2)用XRF微探针分析了陨石中Ti、Cr、Fe的化学状态。利用聚焦x射线微束（最小尺寸约为10 μ m）对陨石中的过渡元素进行了化学形态分析。基于XANES和sixs技术的化学状态作图在黄铁矿后的针铁矿假形态样品中产生了Fe^<2+>和Fe^<3+>离子的分离图。在Allende、Krymka、Semarkona和Y . More amato-691陨石的球粒中，Cr和Ti的化学形态分别以三价和四价为主，而在Yamato-691陨石的球粒中，还存在Cr^<2+>和Ti^<3+>组分。(3)地质样品中硫的二维化学态填图。对含硫沉积岩进行了二维分析，通过改变激发能，成功地获得了硫酸盐和硫化物离子的组成图像。结果直观地反映了岩石试样在风化作用下的氧化过程。(4)钠石族矿物中硫的化学状态分析。钠石族矿物的S - k边XANES光谱表现出特有的化学位移和独特的光谱形状。稀土和橄榄石的光谱分别表现出典型的硫酸盐离子峰和硫化物离子峰。虽然天青石的光谱中有硫化物和硫酸盐硫峰，但天青石的理想分子式为Na6Ca2 (AI,6Si6O24) S2。本研究首次发现了硫酸盐离子的存在。少

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