ELECTRON SPECTROSCOPIC MICROSCOPY IN MATERIALS SCIENCE

研究了九州大学新近安装的新型能量过滤透射电子显微镜的性能和适用性，并与美国马克斯-普朗克研究所和美国亚利桑那州立大学的显微镜进行了比较。KU新型显微镜具有肖特基型场发射枪和欧米茄型成像滤光片。成像能谱仪使我们能够利用包含在非弹性散射电子中的信息，并改善放大图像的对比度以及衍射图案。(1)电子能谱成像：通过改变选能狭缝的位置和宽度，可以选择用于成像的电子的能量。在多光束分辨率图像以及明场和暗场图像中，尽管物镜孔径的大小和位置不同，但滤波后的零损耗图像的对比度有所提高。在滤波后的零损耗图像中，金属和合金中的相干析出物、层错和位错的图像是清晰的。在较厚的试样和较低的加速电压下，能量滤波效果明显。滤过的核损耗（内壳电离）图像包括材料中特定元素的组成信息（元素映射）。在过滤后的k损失氧图像中，硅水中的薄氧化层以二维尺度可见。(2)电子能谱衍射：通过改变衍射模式中的能量狭缝，得到能量滤过的衍射图样。非弹性散射电子是衍射图样的背景。在零损耗滤光衍射图中，背景被很好地消除，对比度大大提高。在选定区域的衍射图中可以观察到弱衍射斑点或弥散极大值，在会聚电子衍射图中可以观察到高阶劳区弱衍射线。

We investigated performance and applicability of the new energy filtering transmission electron microscope which was recently installed in Kyushu University (KU), and compared with those of microscopes in Max-Planck Institute and Arizona State University. The new microscope in KU has a field emission gun of Shottcky type and an imaging filter of omega-type. The imaging energy spectrometer enables us to use the information included in the inelastically scattered electrons and to improve the contrasts of magnified images as well as diffraction patterns.(1) Electron spectroscopic imaging : By changing a position and a width of energy selecting slit, we can select the energy of electrons to be used for imaging. The contrasts of filtered zero-loss images are improved in the multi-beam resolution images as well as bright-field or dark-field images, although the size and position of an objective apertureare are different in these imaging modes. Images of coherent precipitates, stacking faults and dislocations in metals and alloys are sharp in filtered zero-loss images. The effect of energy filtering is pronounced in thicker spsecimen and lower accelerating voltage. A filtered core-loss (inner-shell ionization) image includes information on composition of a particular element in material (element mapping). Thin oxide layer in Si water is visualized in a two-dimensional scale in the filtered K-loss oxygen image.(2) Electron spectroscopic diffraction : Energy filtered diffraction patterns are obtained by changing the energy slit in the diffraction mode. Inelastically scattered electrons are responsible for the background in diffraction patterns. The background is well eliminated and contrast is much improved in the zero-loss filtered diffraction patterns. We can observe weak diffraction spots or diffuse maxima in the selected-area diffraction patters, and weak diffraction lines of a higher order Laue zone in convergent electron diffraction patters.