Mizusawa Mari, Sakurai Kenji
National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan.
J Synchrotron Radiat. 2004 Mar 1;11(Pt 2):209-13. doi: 10.1107/S0909049503028024. Epub 2004 Feb 12.
Gabbroic rocks were collected at Mount Tsukuba in Japan, and their XAFS images were studied using a projection-type X-ray fluorescence (XRF) microscope, which is a powerful new tool recently developed for extremely rapid imaging. The instrument employs a grazing-incidence arrangement in order that primary X-rays illuminate the whole sample surface, as well as parallel-beam optics and an extremely close geometry in order to detect XRF by a high-performance X-ray CCD system with 1024 x 1024 pixels. The XRF image indicated that black amphibole and white feldspar, both of which are typical mineral textures of the rock, contain iron. The origin has been suggested to be several small yellowish-brown minerals contained there. The XAFS imaging has been carried out by repeating the exposure of XRF images during the energy scan of the primary X-rays. It has been found that the structure is qualitatively close to that of olivine, and the main differences found in both areas can be explained as a difference in iron and magnesium concentration, i.e. the mixed ratio of forsterite (Mg(2)SiO(4)) and fayalite (Fe(2)SiO(4)). The feasibility of the present XAFS imaging method has been demonstrated for realistic inhomogeneous minerals.
在日本筑波山采集了辉长岩岩石，并使用投影型X射线荧光（XRF）显微镜研究了它们的XAFS图像，该显微镜是最近开发的用于极快速成像的强大新工具。该仪器采用掠入射装置，以便初级X射线照亮整个样品表面，同时采用平行光束光学系统和极其紧密的几何结构，以便通过具有1024×1024像素的高性能X射线电荷耦合器件（CCD）系统检测XRF。XRF图像表明，黑色角闪石和白色长石这两种岩石的典型矿物纹理都含铁。有人认为其来源是其中所含的几种黄褐色小矿物。通过在初级X射线的能量扫描过程中重复曝光XRF图像来进行XAFS成像。已经发现该结构在定性上与橄榄石的结构相近，并且在两个区域发现的主要差异可以解释为铁和镁浓度的差异，即镁橄榄石（Mg₂SiO₄）和铁橄榄石（Fe₂SiO₄）的混合比例。本XAFS成像方法对于实际的非均匀矿物已证明其可行性。
