Development of precise morphological analysis methods with electron holography

本项目旨在通过使用电子全息术开发新的形态分析方法。电子全息研究的硬件是在我们的场致发射透射电子显微镜上安装一根直径为0.6μm的铂丝作为双棱镜和一台电视摄像机。利用该装置，我们可以利用场致发射体的明亮照明观察各种材料的电子全息图，并对全息图进行定量记录，这是进行精确形态分析所必需的，我们还开发了一个计算程序，可以高精度地计算全息图的相移。如果使用上述系统记录全息图，则获得作为二维数字数据的全息图。通过数字化全息图的傅里叶变换可以知道相移。该程序可用于复杂形状试件的评价，也可用于分析 ...更多信息 利用本项目开发的方法，对形状可控的SiO_2颗粒等进行了精确的形貌分析。作为厚度测量的一种方法，电子能量损失谱（EELS）由于测量和分析简单而被广泛接受。然而，这种方法不能应用于极薄的样本。结果表明，电子能量损失谱可应用的最小厚度约为30nm，而电子全息可测量小于10nm的厚度。作为另一个应用，我们已经准确地确定了充电的大小，这是一个麻烦的现象，在观察绝缘体。通过计算模拟全息图与观测结果之间的剩余折射率，确定了SiO_2粒子中带电的大小。本工作建立了基于电子全息的形貌分析方法，可应用于许多先进材料。少

This project aimed to develop new methods of morphological analysis by using electron holography. The results are summarized as follows.The hardware of electron holography studies was constructed by installing a platinum wire of 0.6μm φ, as a biprism, and a TV camera into our transmission electron microscope with a field emitter. This equipment has enabled us to observe electron holograms of various materials owing to the bright illumination from the field emitter, and to record the holograms quantitatively, which is necessary to carry out a precise morphological analysis.We also developed a computer program that could evaluate the phase shift of holograms with high precision. The holograms are obtained as two-dimensional digital data if they are recorded by using the system as described above. It is possible to know the phase shift by Fourier transformations of the digitized holograms. This program can be applied to evaluations of specimens with complicated shapes, as well as analyzes … More of magnetic domain structures of various materials.By using the methods developed in this project, some precise morphological analyzes were carried out with shape controlled SiO_2 particles etc. As a way of thickness measurement, electron energy-loss spectroscopy (EELS) has been widely accepted because of the simplicity of measurements and analyzes. However, this method cannot be applied to extremely thin specimens. It was shown in the present work that the minimum thickness, to which EELS could be applied, was about 30nm, while the electron holography can evaluate the thickness less than 10 nm. As another application, we have accurately determined the magnitude of charging, which is a troublesome phenomenon in observations of insulators. The magnitude of charging in SiO_2 particles was determined by evaluating the residual index between the simulated hologram and the observation.The electron holography has been used to discuss some peculiar phenomena of physics to date. The present work has established useful methods of morphological analyzes based on the electron holography, which can be applied to many advanced materials. Less