波动电子显微镜的定量校正。

IF 1.9 4区 工程技术 Q3 MICROSCOPY
J M Gibson, M M J Treacy
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引用次数: 0

摘要

波动电子显微镜(FEM)中异常低的归一化方差经常被报道。我们提出了三个实验修正的定量解释,显著修改传统的方法。有限元法依赖于相干纳米衍射模式的强度统计测量。我们证明了用像素化检测器对纳米衍射图进行采样可以去除高频信号并减少统计方差。最显著的影响是背景归一化方差,它来自随机原子排列,不同于与中范围顺序相关排列相关的归一化方差峰。事实上,我们表明,如果峰是背景减去,它们的高度受探测器效应的影响要小得多,只要实验条件是优化的。我们表明,镜头噪声校正也必须调整,以说明相机调制传递函数(MTF)的影响。此外,我们通过实验证明了传统的a-Si厚度校正方法是不够的,并提出了一种替代方法来解决厚度变化。我们从辐射下样品“飘动”引起的位移退相干的角度推测了异常厚度效应的起源。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Quantitative corrections for fluctuation electron microscopy.

Anomalously low values of the normalised variance in fluctuation electron microscopy (FEM) have been frequently reported. We present three experimental corrections for quantitative interpretation that significantly modify conventional approaches. FEM relies on measurements of intensity statistics in coherent nanodiffraction patterns. We demonstrate that sampling the nanodiffraction patterns with a pixelated detector removes high-frequency signals and reduces statistical variance. The most significant impact is on the background normalised variance, which arises from random atomic alignments and is distinct from the normalised variance peaks associated with the correlated alignments of medium-range order. Indeed, we show that if the peaks are background-subtracted, their height is much less affected by the detector effect, provided the experimental conditions are optimised. We show that shot noise correction must also be adjusted to account for the camera Modulation Transfer Function (MTF) effects. Additionally, we demonstrate through experiment that the traditional method of thickness correction for a-Si is inadequate and propose an alternative approach to address thickness variations. We speculate on the origin of the anomalous thickness effect in terms of displacement decoherence due to sample 'fluttering' under irradiation.

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来源期刊
Journal of microscopy
Journal of microscopy 工程技术-显微镜技术
CiteScore
4.30
自引率
5.00%
发文量
83
审稿时长
1 months
期刊介绍: The Journal of Microscopy is the oldest journal dedicated to the science of microscopy and the only peer-reviewed publication of the Royal Microscopical Society. It publishes papers that report on the very latest developments in microscopy such as advances in microscopy techniques or novel areas of application. The Journal does not seek to publish routine applications of microscopy or specimen preparation even though the submission may otherwise have a high scientific merit. The scope covers research in the physical and biological sciences and covers imaging methods using light, electrons, X-rays and other radiations as well as atomic force and near field techniques. Interdisciplinary research is welcome. Papers pertaining to microscopy are also welcomed on optical theory, spectroscopy, novel specimen preparation and manipulation methods and image recording, processing and analysis including dynamic analysis of living specimens. Publication types include full papers, hot topic fast tracked communications and review articles. Authors considering submitting a review article should contact the editorial office first.
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