Decipherment of important reoord concerning the earth and planet activity that remains in local structure of trace elements

本研究试图解读微量元素局部结构中有关地球和行星活动的重要记录。通过X射线吸收光谱和X射线衍射方法获得了关于特定种类元素周围的精确局部结构的信息。物理性质测量、电子状态测量和结构分析紧密结合，以研究极端条件下熔体、非晶和晶体材料的细节。实验采用Spring-8同步加速器等世界顶级设备进行。本研究的目的是建立将纳米结构、宏观性质与地球内部等多元素多相的结构和历史联系起来的理论，利用XAFS光谱研究K-T边界粘土中微量元素的局域结构。K-T边界粘土中As作为一种过度富集的元素占据了矿物的As 04四面体位，通过与几种砷矿物的比较，XAFS谱的特征与As（+5）矿物的值吻合较好。Al_2SiO_5蓝晶石中的客体Fe元素由于经历了高压和高氧化条件，具有较高的四价价态，Fe-0键距为1.865（7）（A）。研究了稀有气体在矿物中的局域结构和反应性。在高温高压条件下合成了几种稀有气体掺杂的矿物，并对其进行了质谱和XAFS分析。有趣的是，惰性气体和相邻原子之间的原子距离似乎比简单吸附情况下预期的距离要短。这些结果表明，稀有气体可能被束缚在样品中的相互作用强于吸附和/或存在于主机矿物的结构的内部网站。

This research is an attempt to read the important record concerning the earth and planet activity that remains in local structure of trace elements. Information on a precise local structure around a specific kind element is obtained by X-ray abscxption spectroscopy and the X-ray diffraction methods. Physical properties measurement, electronic state measurements and structure analyses are put into close contact to investigate details of the melts, amorphous and crystals materials under extreme conditions. The experiments are performed in-situ, by using world's top level equipments such as Spring-8 synchrotron facilities. The research aims the construction of the theory that links the nanometer-level structure, the macroscopic properties and the textures and history in multi element and multi phases such as the Earth's interior.Local structure of trace elements in K-T boundary clays was studied by XAFS spectroscopy. Arsenic as an excessively concentrated element occupies the As04 tetrahedral site of a mineral in K-T boundary clays and the characterization of XAFS spectra agree well with the values of As(+5)minerals according to the comparison with several types of arsenic minerals. The guest Fe elements in Al2SiO5 kyanite have higher-valence states of tetravalent and the Fe-0 bond distance is of 1.865(7)(A)because kyanite had been experienced the high pressure and high oxidized conditions. The local structure and reactivity of noble gas in minerals has been investigated. Several kinds of noble gas-doped minerals were synthesized under high pressures and temperatures and were subjected to mass spectroscopy and XAFS. Interestingly, the atomic distances between noble gas and neighboring atoms appeared to be shorter than the distances expected for the case of simple adsorption. These results suggest that noble gas might be bound in the samples with interaction stronger than the adsorption and/or exist in the internal sites of the structure of the host minerals.