Annular dark-field

The annular dark-field detector of the field-emission STEM (see Figure 2) provides a powerful high-resolution imaging mode that is not available in the conventional TEM or TEM/STEM. In this mode, images of individual atoms may be obtained, as shown in Figure 4 (see Isaacson, Ohtsuki, and Utlaut ). Some annular dark-field... 

S. J. Pennycook. EMSA Bulletin. 19, 67, 1989. A summary of compositional imaging using a high-angle annular dark-field detector in a field emission STEM instrument published by the Electron Microscopy Society of America, Box EMSA Woods Hole, MA 02543. 

Figure 5. Pd supported on carbon a) annular dark-field STEM image revealing particles as small 2nm, b) processed digital x-ray image showing that Pd particles 4nm and larger can be imaged using Pd x-rays alone.

S5mthetic resin-embedded alfalfa samples were oven dried at 65 °C for 24 h and cut at 40-90 nm. The slides were analyzed using a JEOL 2010-F TEM prepared with field emission gun, EDS, and a high angle annular dark field detector for the analysis of solitary nanoparticles. 

Fig. 12. Schematic of the information from HRSTEM, DF, and high-angle annular dark-field (HAADF) microscopy.

Figure 1 Diagrams showing the essential electron-optical configurations used for various imaging modes in CTEM and STEM as seen by two points A and B on the sample, (a) CTEM axial bright field, (b) CTEM tilted dark field, (c) CTEM hollow cone dark field, and (d) STEM with bright field and annular dark field detectors.

Figure 2 STEM images of a 8%wtPd/2%wtPt catalyst supported on charcoal, (a) Bright field, (b) annular dark field, (c) energy loss and (d) ratio of annular dark field/energy loss.

High-Angular Annular Dark-Field Scanning Transmission Electron Microscopy... 

O.L. Krivanek, M.F. Chisholm, V. Nicolosi, T.J. Pennycook, G.). Corbin, N. Dellby, et al., Atom-by-atom structural and chemical analysis by annular dark-field electron microscopy, Nature, 464 (2010) 571-574. 

It is sometimes argued that - by reciprocity - STEM and HRTEM can perform similar tasks since a STEM can be thought of as a HRTEM with detector and electron source being exchanged if the detector is a point detector on the optical axis . Indeed, bright field -and annular dark field imaging can be executed in either a STEM or a HRTEM as shown for the latter in Figure 4. ... 

Figure 4. Bright - and annular dark field image of a CdSe tetrapod and an adjacent gold particle recorded in a TEM. The line profiles demonstrate Z-contrast in the dark field image.

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