Zuo J M, Gao M, Tao J, Li B Q, Twesten R, Petrov I
Department of Material Science and Engineering and F. Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Microsc Res Tech. 2004 Aug;64(5-6):347-55. doi: 10.1002/jemt.20096.
We describe the new coherent nano-area electron diffraction (NED) and its application for structure determination of individual nanostructures. The study is motivated by the challenge and the general lack of analytical techniques for characterizing nanometer-sized, heterogeneous phases. We show that by focusing electrons on the focal plane of the pre-objective lens using a 3rd condenser lens and a small condense aperture, it is possible to achieve a nanometer-sized highly parallel illumination or probe. The high angular resolution of diffraction pattern from the parallel illumination allows over-sampling and consequently the solution of phase problem based on the recently developed ab initio phase retrieval technique. From this, a high-contrast and high-resolution image can be reconstructed at resolution beyond the performance limit of the image-forming objective lens. The significance of NED for nanostructure characterization will be exemplified by single-wall carbon nanotubes and small metallic clusters. Imaging from diffraction patterns, or diffractive imaging, will be demonstrated using double-wall carbon nanotubes.
我们描述了一种新型的相干纳米区域电子衍射（NED）及其在单个纳米结构结构测定中的应用。这项研究的动机是表征纳米尺寸异质相的分析技术面临的挑战以及普遍缺乏此类技术的现状。我们表明，通过使用第三聚光镜和小聚光孔径将电子聚焦在物镜前焦平面上，可以实现纳米尺寸的高度平行照明或探针。来自平行照明的衍射图案的高角分辨率允许过采样，从而基于最近开发的从头算相位恢复技术解决相位问题。由此，可以在超过成像物镜性能极限的分辨率下重建高对比度和高分辨率图像。NED对纳米结构表征的重要性将以单壁碳纳米管和小金属簇为例进行说明。将使用双壁碳纳米管展示从衍射图案进行成像，即衍射成像。
