Development of Electron Emission Microscope Using Metastable Atoms as Probe and Its Application to Studies of Solid Surfaces

以亚稳态原子、低能电子和光子为探针的电子发射显微镜(EEM)已被开发出来，并应用于各种固体表面(金属、半导体、有机薄膜等的表面)的观察。与广泛使用的电子显微镜(如透射电子显微镜和扫描电子显微镜)相比，电子显微镜(1)提供与表面的电子结构直接相关的信息，(2)对表面选择性敏感，(3)几乎不破坏表面。与其他电子显微镜相比，我们新的电子显微镜具有以下特点：(1)电子光学系统保持在超高真空下进行表面观察。(2)成像系统中包括一个能量分析仪，使我们能够测量表面微区的能谱，还可以观察能量选择的图像。(3)电子显微镜可以用作亚稳态电子发射显微镜(MEEM)，低能电子e…。更多的是任务显微镜(LEEM)和光电子发射显微镜(PEEM)对应的三种探头。MEEM提供关于表面最外层的信息，而LEEM和PEEM提供关于顶部几层的信息。此外，使用电子探针的镜面电子显微镜(MEM)提供了反映表面电势的图像。本研究的中心目的是发展镜面电子显微镜并最终实现这一点：首次获得了表面的MEEM图像和表面微区的亚稳态原子电子能谱(MAES)。结果表明，MEEM可以灵敏地观察到表面微区最外层的电子态和分子取向，适合于其他显微镜难以观察到的表面(吸附表面、有机材料表面和生物体系表面)，因为亚稳原子通过热扩散引入，速度很小，几乎不会破坏样品表面。较少

An electron emission microscope (EEM) using metastable atoms, low energy electrons, and photons as probes, has been developed and applied to the observation of various solid surfaces (surfaces of metals, semiconductors, thin organic films, etc.). Compared with the widely used microscopes such as the transmission electron microscope (TEM) and the scanning electron microscope (SEM), the EEM (1) provides information directly related to the electronic structure of the surface, (2) is selectively sensitive to the surface, and (3) scarcely destroys the surface.In contrast to other EEM, our new EEM has the following characteristics :(1) The electron optical system is kept under ultra-high vacuum for the purpose of the surface observation.(2) An energy analyzer included in the imaging system allows us to measure energy spectra in the surface micro-region and also to observe energy-selected images.(3) The EEM can be used as a metastable electron emission microscope (MEEM), low-energy electron e … More mission microscope (LEEM), and photoelectron emission microscope (PEEM) corresponding to three kinds of probes. The MEEM provides information on the outermost layr of the surface and the LEEM and PEEM give information on the top several layrs. Furthermore, the mirror electron microscope (MEM) using the electron probe, provides images reflecting the electrical potential of the surface.The central purpose of this study has been the development of the MEEM and this has been finally achieved : The MEEM images of the surface and the metastable atom electron spectrum (MAES) of the surface micro-region have been obtained for the first time. It has been shown that the MEEM enables us to observe sensitively the electronic state and the molecular orientation of the outermost layr in the micro-region of the surface.The MEEM is suitable for surfaces that are difficult to be observed by other microscopes (adsorbed surfaces, and surfaces of organic materials and biological systems), because, being introduced by thermal diffusion, metastable atoms have small velocity and scarcely destroy sample surfaces. Less