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

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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.