Development of X-ray polarization microscopy

本研究的目的是开发一个X射线偏振显微镜，使我们能够观察到X射线光谱范围内的偏振对比图像，使之与线性流变（LD）和循环流变（CD）相对应。这一方法可应用于对X射线能量范围内的材料的不同观察。本研究的内容包括：（1）开发高分辨率CCD x射线探测器;（2）观察x射线图像的偏振对比度与x射线线性流变学（XLD）;（3）观察x射线图像的偏振对比度与x射线磁性循环流变学（XMCD）;（1）高分辨率CCD x射线探测器的关键内容是磷酸机屏幕将x射线转换为可见光。磷酸盐的响应和空间分辨率的转换有效性、非统一性、通过选择磷酸盐材料、厚度、沉积方法和基础材料进行了优化。As a result， Gd-D22-D2O-D22-D2S：Tb（P-43） with a 10 micron thickness has been chosen。当CCD x射线探测器与这个磷酸盐结合在一起时，用Si 111不对称晶体的x射线放大器，这个成像系统显示出1.2微米的空间分辨率。（2）极化对比度与X射线线性流变（XLD）的图像在K边缘（7709 eV）上成功地观察到钴单晶体。现在是极化-对比图像到XLD的拳头时间，可以在硬X射线范围内观察到。（3）与X射线磁循环失调的极化对比图像（XMCD）在K边缘成功地观察到钴多晶体（7709 eV）。

The purpose of this study is to develop an x-ray polarization microscopy which enables us to observe images of polarization contrast due to linear dichroism (LD) and circular dichroism (CD) in x-ray spectral range. This method can be applied to the observation of anisotropy of materials in x-ray energy range. This study consists of (1) Development of high resolution CCD x-ray detector, (2) Observation of x-ray images of polarization contrast due to x-ray linear dichroism (XLD), and (3) Observation of x-ray images of polarization contrast due to x-ray magnetic circular dichroism (XMCD)(1) The critical element of the high resolution CCD x-ray detector is a phosphor screen to convert x-rays to visible light. The conversion efficiency, non-uniformity of response and spatial resolution of the phosphor have been optimized by choosing phosphor materials, thicknesses, deposition methods, substrate materials. As a result, GdィイD22ィエD2OィイD22ィエD2S:Tb(P-43) with a 10 micron thickness has been chosen. When the CCD x-ray detector with this phosphor is combined with an x-ray magnifier made of Si 111 asymmetric crystal, this imaging system has shown a spatial resolution of 1.2 micron.(2) Images of polarization contrast due to x-ray linear dichroism (XLD) has been successfully observed with cobalt single crystal at K-edge (7709 eV). It is the fist time that the polarization-contrast image due to XLD is observed in hard x-ray range.(3) Images of polarization contrast due to x-ray magnetic circular dichroism (XMCD) has been successfully observed with cobalt poly-crystals at K-edge (7709 eV).