Laboratorium für Elektronenmikroskopie and Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), Germany.
J Microsc. 2011 Jul;243(1):31-9. doi: 10.1111/j.1365-2818.2010.03475.x. Epub 2010 Dec 13.
High-angle annular dark-field scanning transmission electron microscopy (HAADF STEM) at low energies (≤30 keV) was used to study quantitatively electron scattering in amorphous carbon and carbon-based materials. Experimental HAADF STEM intensities from samples with well-known composition and thickness are compared with results of Monte Carlo simulations and semiempirical equations describing multiple electron scattering. A well-defined relationship is found between the maximum HAADF STEM intensity and sample thickness which is exploited (a) to derive a quantitative description for the mean quadratic scattering angle and (b) to calculate the transmitted HAADF STEM intensity as a function of the relevant materials parameters and electron energy. The formalism can be also applied to determine TEM sample thicknesses by minimizing the contrast of the sample as a function of the electron energy.
采用低能（≤30 keV）高角环形暗场扫描透射电子显微镜（HAADF STEM）对非晶碳和碳基材料中的电子散射进行定量研究。将具有已知成分和厚度的样品的实验 HAADF STEM 强度与蒙特卡罗模拟和描述多次电子散射的半经验方程的结果进行比较。发现最大 HAADF STEM 强度与样品厚度之间存在明确的关系，该关系可用于(a)推导出平均二次散射角的定量描述，以及(b)计算作为相关材料参数和电子能量函数的透射 HAADF STEM 强度。该形式还可应用于通过最小化电子能量函数下的样品对比度来确定 TEM 样品厚度。
