Scanning transmission electron microscopy at low electron energies: basic principles, modelling and quantification

与第一个项目阶段一样，第二个项目阶段的总体目标是关于在电子能量低于30keV的扫描透射电子显微镜(STEM)中形成对比度的基础研究。这些能量对于扫描电子显微镜来说是典型的，它可以用固态STEM探测器来拟合，以研究电子透明样品。分辨率略高于1 nm，足以解决生命科学、材料科学和纳米技术中的许多问题。低能量STEM可以使(S)在高电子能量下精细的电子显微镜研究过时，这使得低能量STEM成为一种经济高效的替代方案。低电子能量的另一个优点是可以忽略不计的碰撞损伤。第二个项目阶段的具体目标将是a)轴向透射式衍射花样的研究，b)由于多次/多重散射而导致的样品中的光束展宽作为低能STEM分辨率的限制因素，c)缺陷表征和d)最终澄清低密度和低原子序数材料低于15keV的电子能量的HAADF STEM实验强度和计算强度之间的来源。低能STEM将用于量化不同纳米级材料的样品性质。

General goals of the 2nd project phase are, as in the 1st project phase, basic studies regarding contrast formation in scanning transmission electron microscopy (STEM) at electron energies below 30 keV. These energies are typical for scanning electron microscopes which can be fitted by a solid-state STEM detector for the study of electron transparent samples. The resolution is slightly better than 1 nm which is sufficient for solving numerous questions in life science, materials science and nanotechnology. Low-energy STEM can make elaborate (S)TEM studies at high electron energies obsolete which makes low-energy STEM a cost-efficient alternative. Another advantage of the low electron energies is negligible knock-on damage. Specific goals of the 2nd project phase will be a) the study of axial transmission diffraction patterns, b) beam broadening in the sample due to multiple/plural scattering as limiting factor for the resolution in low-energy STEM, c) defect characterization and d) final clarification of the origin between experimental and calculated HAADF STEM intensities for electron energies below 15 keV for low-density and low-atomic-number materials. Low-energy STEM will be applied to quantify sample properties of different nanoscaled materials.