Dark-field detector, annular

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. 

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. 

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.

Improved annular dark field detectors for the scanning transmission electron microscopes may assist in detecting lnm crystallites. For tailoring a catalyst to a specific reaction, one must be able to relate the structure of the site to catalytic activity and selectivity. Possibly future developments in high resolution electron microscopy will address this problem. 

Such is not the case if, instead of the axial detector, we employ the annular dark-field detector for which P la 1, where P is the effective angle subtended by the detector. Under these circumstances we anticipate that phase contrast will not contribute significantly to the image. Instead, modulation of the amplitude-contrast transfer function should be noted in an image if, for example, a probe of FWHM comparable to atomic separations is scanned across a sharp edge or a periodic structure. This is observed in Figure 8, in which a probe of FWHM 3 A is scanned across... 

Figure 12 SAD channelling pattern recorded with annular dark-field detector for Au single crystal...

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