Development of high-energy X-ray fluorescence analysis and application to the study of origin of earth and planetary materials

传统上，重元素的x射线荧光（XRF）分析是基于它们的l系列谱线。这是因为这些元素的k线很难被市售的XRF光谱仪激发。典型的多组分材料的能量色散x射线荧光光谱在小于20kev的能量区通常挤满了各组分元素的K， L和M发射线的重叠。相比之下，20keV以上的XRF光谱只有K线，光谱变得简单。因此，k谱线是分析原子序数Z≧45 （=Rh Kα_1=20.12 KeV）的重元素的理想方法。我们首次利用来自Spring-8同步辐射源的116keV x射线开发了高能XRF分析，并发现该技术使我们能够以足够的灵敏度确定所有重元素。最低检出限为亚ppm水平。该技术已成功应用于石榴石中重元素分区的二维分析、汽车涂料的法医鉴定、久谷和有田古瓷的物源分析，并阐明了该技术的潜在优势。高能XRF分析将成为分析环境样品、考古样品、法医样品、地球化学样品以及含有稀土元素等重元素的高科技材料的强大工具。预计高能x射线的利用将为x射线荧光分析开辟新的应用领域

Traditionally, the X-ray fluorescence (XRF) analysis of heavy elements is based on their L-series spectral lines. This is because the K-lines of these elements are difficult to excite by commercially available XRF spectrometers. A typical energy dispersive X-ray fluorescence spectrum of a multi-component material in energy regions of less than 20 keV is usually crowded with an overlap of the K, L, and M emission lines of the component elements. In contrast, the XRF spectrum above 20keV contains only K lines, and the spectrum becomes simple. Therefore, the use of the K-lines is ideal for the analysis of heavy elements of atomic number Z ≧45 (=Rh Kα_1=20.12 KeV). We have developed for the first time high energy XRF analysis utilizing 116keV X-rays from synchrotron radiation source of Spring-8 and found that this technique enables us to determine all heavy elements with sufficient sensitivity. The minimum detection limit was at a sub-ppm level. This technique has been successfully applied to two-dimensional analysis of zoning of heavy elements in garnet, forensic identification of automobile paints, provenance analysis of old-china wares from Kutani and Arita and the potential advantages of this technique have been elucidated. High-energy XRF analyses will become a powerful tool for analyzing environmental samples, archaeological samples, forensic samples, geochemical samples, and high-tech materials containing heavy elements such as rare earth elements. It is expected that the utilization of high-energy X-rays will open new application fields for X-ray fluorescence analyses