Transmission electron microscopy at 20 kV for imaging and spectroscopy
Transmission electron microscopy at 20 kV for imaging and spectroscopy
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DOI：
10.1016/j.ultramic.2011.03.012
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发表时间：
2011-07-01
期刊：
影响因子：
2.2
通讯作者：
Benner, G.
中科院分区：
文献类型：
--
作者：
Kaiser, U.;Biskupek, J.;Benner, G.
透射电子显微镜（TEM）的电子光学性能的特点是直接空间成像和光谱使用电子能量低至20键。这款高度稳定的仪器配备了静电单色仪和C-S校正器。在20 kV下，即使对于具有213 μ m晶格转移的单层石墨烯，也显示出高图像对比度（倾斜照明）。对于4 nm厚的Si，200次反射（271.5 μ m）被直接转移（轴向照射）。我们表明，在20 kV下，碳纳米管容器内的辐射敏感富勒烯（C-60）能够承受比80 kV下高出约两个数量级的电子剂量。在光谱模式下，单色低能电子束能够以极低的背景噪声采集高达非常高的能量损失的EELS光谱。使用Si和Ge，我们表明，20 kV TEM可以确定介电性能和窄带隙，这是迄今为止TEM无法访问的。这些最初的结果表明，低kV TEM是一个令人兴奋的新工具，用于确定不同类型的纳米材料的结构和电子特性。(C)2011 Elsevier B. V.保留所有权利。
The electron optical performance of a transmission electron microscope (TEM) is characterized for direct spatial imaging and spectroscopy using electrons with energies as low as 20 key. The highly stable instrument is equipped with an electrostatic monochromator and a C-S-corrector. At 20 kV it shows high image contrast even for single-layer graphene with a lattice transfer of 213 pm (tilted illumination). For 4 nm thick Si, the 200 reflections (271.5 pm) were directly transferred (axial illumination). We show at 20 kV that radiation-sensitive fullerenes (C-60) within a carbon nanotube container withstand an about two orders of magnitude higher electron dose than at 80 kV. In spectroscopy mode, the monochromated low-energy electron beam enables the acquisition of EELS spectra up to very high energy losses with exceptionally low background noise. Using Si and Ge, we show that 20 kV TEM allows the determination of dielectric properties and narrow band gaps, which were not accessible by TEM so far. These very first results demonstrate that low kV TEM is an exciting new tool for determination of structural and electronic properties of different types of nano-materials. (C) 2011 Elsevier B.V. All rights reserved.