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This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
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Annular dark-field transmission electron microscopy (ADF-TEM) is widely used to evaluate the mass-thickness, atomic number and imaging of TEM samples. A simple ADF-aperture setup uses an annular objective aperture that acts as a central beam stop in the back focal plane of the objective lens [1 – 5] as shown in Figure 3889. This aperture also blocks the outer electrons scattered at very high semiangles. Therefore, the central beam and all electrons scattered at very high semiangle are excluded from imaging. By optimizing the dimension of the inner and outer rings (~ 86 µm for the inner ring and ~200 µm for the outer ring in Figure 3889), many applications can be obtained. The SEM (secondary electron microscopy) image in Figure 3889 (b) shows an annular aperture fabricated using focused-ion-beam (FIB) technique.
Figure 3889. a) Schematic illustration of the column of a scanning transmission electron
microscope (STEM) system. b) An ADF aperture prepared using focused-ion-beam (FIB) technique.
[1] K. Heinemann, H. Poppa, Phys. Rev. Lett. 1972, 20, 122.
[2] Z. L. Wang, A. T. Fisher, Ultramicroscopy 1993, 43, 183.
[3] Z. L. Wang, Ultramicroscopy 1994, 53, 73.
[4] S. Bals, B. Kabius, M. Haider, V. Radmilovic, C. Kisielowski, Solid
State Commun. 2004, 130, 675.
[5] S. Bals, R. Kilaas, C. Kisielowski, Ultramicroscopy 2005, 104, 281.
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