扫描透射电子显微镜
暗场显微术
分辨率(逻辑)
电子
原子序数
光学
高分辨率透射电子显微镜
计算物理学
材料科学
原子物理学
透射电子显微镜
物理
显微镜
人工智能
计算机科学
量子力学
作者
Sandra Van Aert,Johan Verbeeck,Rolf Erni,Sara Bals,M. Luysberg,D. Van Dyck,Gustaaf Van Tendeloo
出处
期刊:Ultramicroscopy
[Elsevier]
日期:2009-09-01
卷期号:109 (10): 1236-1244
被引量:198
标识
DOI:10.1016/j.ultramic.2009.05.010
摘要
A model-based method is proposed to relatively quantify the chemical composition of atomic columns using high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) images. The method is based on a quantification of the total intensity of the scattered electrons for the individual atomic columns using statistical parameter estimation theory. In order to apply this theory, a model is required describing the image contrast of the HAADF STEM images. Therefore, a simple, effective incoherent model has been assumed which takes the probe intensity profile into account. The scattered intensities can then be estimated by fitting this model to an experimental HAADF STEM image. These estimates are used as a performance measure to distinguish between different atomic column types and to identify the nature of unknown columns with good accuracy and precision using statistical hypothesis testing. The reliability of the method is supported by means of simulated HAADF STEM images as well as a combination of experimental images and electron energy-loss spectra. It is experimentally shown that statistically meaningful information on the composition of individual columns can be obtained even if the difference in averaged atomic number Z is only 3. Using this method, quantitative mapping at atomic resolution using HAADF STEM images only has become possible without the need of simultaneously recorded electron energy loss spectra.
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