Volcano structure in atomic resolution core-loss images

被引:33
作者
D'Alfonso, A. J. [1 ]
Findlay, S. D. [1 ]
Oxley, M. P. [2 ]
Allen, L. J. [1 ]
机构
[1] Univ Melbourne, Sch Phys, Melbourne, Vic 3010, Australia
[2] Oak Ridge Natl Lab, Div Mat Sci & Technol, Oak Ridge, TN 37831 USA
基金
澳大利亚研究理事会;
关键词
dipole approximation; nonlocality; STEM; electron energy loss spectroscopy; aberration correction;
D O I
10.1016/j.ultramic.2007.10.011
中图分类号
TH742 [显微镜];
学科分类号
摘要
A feature commonly present in simulations of atomic resolution electron energy loss spectroscopy images in the scanning transmission electron microscope is the volcano or donut structure. In the past this has been understood in terms of a geometrical perspective using a dipole approximation. It is shown that the dipole approximation for core-loss spectroscopy begins to break down as the probe forming aperture semi-angle increases, necessitating the inclusion of higher order terms for a quantitative understanding of volcano formation. Using such simulations we further investigate the mechanisms behind the formation of such structures in the single atom case and extend this to the case of crystals. The cubic SrTiO3 crystal is used as a test case to show the effects of nonlocality, probe channelling and absorption in producing the volcano structure in crystal images. (C) 2007 Elsevier B.V. All rights reserved.
引用
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页码:677 / 687
页数:11
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