In electron microscopy, the maximum a posteriori (MAP) probability rule has been introduced as a tool to determine the most probable atomic structure from high-resolution annular dark-field (ADF) scanning transmission electron microscopy (STEM) images exhibiting low contrast-to-noise ratio (CNR). Besides ADF imaging, STEM can also be applied in the annular bright-field (ABF) regime. The ABF STEM mode allows to directly visualize light-element atomic columns in the presence of heavy columns. Typically, light-element nanomaterials are sensitive to the electron beam, limiting the incoming electron dose in order to avoid beam damage and leading to images exhibiting low CNR. Therefore, it is of interest to apply the MAP probability rule not only to ADF STEM images, but to ABF STEM images as well. In this work, the methodology of the MAP rule, which combines statistical parameter estimation theory and model-order selection, is extended to be applied to simultaneously acquired ABF and ADF STEM images. For this, an extension of the commonly used parametric models in STEM is proposed. Hereby, the effect of specimen tilt has been taken into account, since small tilts from the crystal zone axis affect, especially, ABF STEM intensities. Using simulations as well as experimental data, it is shown that the proposed methodology can be successfully used to detect light elements in the presence of heavy elements.

中文翻译：

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从同时采集的 ABF 和 ADF STEM 图像中检测原子柱

在电子显微镜中，引入了最大后验 (MAP) 概率规则作为从高分辨率环形暗场 (ADF) 扫描透射电子显微镜 (STEM) 图像中确定最可能的原子结构的工具- 噪声比（CNR）。除了 ADF 成像，STEM 还可以应用于环形明场 (ABF) 区域。ABF STEM 模式允许在存在重柱的情况下直接可视化轻元素原子柱。通常，轻元素纳米材料对电子束很敏感，限制了进入的电子剂量以避免电子束损坏并导致图像表现出低 CNR。因此，不仅将 MAP 概率规则应用于 ADF STEM 图像，而且还应用于 ABF STEM 图像，这很有趣。在这项工作中，MAP 规则的方法论，它结合了统计参数估计理论和模型阶数选择，扩展到应用于同时获取的 ABF 和 ADF STEM 图像。为此，建议对 STEM 中常用的参数模型进行扩展。因此，试样倾斜的影响已被考虑在内，因为与晶区轴的小倾斜尤其会影响 ABF STEM 强度。使用模拟和实验数据表明，所提出的方法可以成功地用于在重元素存在的情况下检测轻元素。试样倾斜的影响已被考虑在内，因为与晶区轴的小倾斜尤其会影响 ABF STEM 强度。使用模拟和实验数据表明，所提出的方法可以成功地用于在重元素存在的情况下检测轻元素。试样倾斜的影响已被考虑在内，因为与晶区轴的小倾斜尤其会影响 ABF STEM 强度。使用模拟和实验数据表明，所提出的方法可以成功地用于在重元素存在的情况下检测轻元素。