It is well known that dynamical diffraction varies with changes in sample thickness and local crystal orientation (due to sample bending). In differential phase contrast scanning transmission electron microscopy (DPC-STEM), this can produce contrast comparable to that arising from the long-range electromagnetic fields probed by this technique. Through simulation we explore the scale of these dynamical diffraction artefacts and introduce a metric for the magnitude of their contribution to the contrast. We show that precession over an angular range of a few milliradian can suppress this contribution to the contrast by one-to-two orders of magnitude. Our exploration centres around a case study of GaAs near the [011] zone-axis orientation using a probe-forming aperture semiangle on the order of 0.1 mrad at 300 keV, but the trends found and methodology used are expected to apply more generally.

中文翻译：

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通过进动抑制长程电磁场微分相差扫描透射电子显微镜中的动态衍射伪影

众所周知，动态衍射随样品厚度和局部晶体取向（由于样品弯曲）的变化而变化。在微分相差扫描透射电子显微镜 (DPC-STEM) 中，这可以产生与该技术探测的远程电磁场产生的对比度相当的对比度。通过模拟，我们探索了这些动态衍射人工制品的规模，并引入了衡量它们对对比度贡献的大小的度量。我们表明，在几毫弧度的角度范围内的进动可以将这种对对比度的贡献抑制一到两个数量级。我们的探索围绕 [011] 区轴方向附近的 GaAs 案例研究，使用 300 keV 下 0.1 mrad 数量级的探针形成孔径半角，