Electrons forming images with

In image mode, the post-specimen lenses are set to examine the information in the transmitted signal at the image plane of the objective lens. Here, the scattered electron waves finally recombine, forming an image with recognizable details related to the sample microstructure (or atomic structure). 

Analysis of individual catalyst particles less than IMm in size requires an analytical tool that focuses electrons to a small probe on the specimen. Analytical electron microscopy is usually performed with either a dedicated scanning transmission electron microscope (STEM) or a conventional transmission electron microscope (TEM) with a STEM attachment. These instruments produce 1 to 50nm diameter electron probes that can be scanned across a thin specimen to form an image or stopped on an image feature to perform an analysis. In most cases, an electron beam current of about 1 nanoampere is required to produce an analytical signal in a reasonable time. 

Nanotubes of tin (Scanning electron microscope image by S. Schlecht, Freie Universitat Berlin. Reprinted form Angewandte Chemie 118 (2006) 317, with permission from Wiley-VCH)... 

Fig. 18.5 Scanning electron microscope images showing cross sections of ARROWS with (a) trapezoidal geometry formed from an aluminum core, (b) rectangular geometry formed from an SU8 core, and (c) arched geometry formed from a reflowed photoresist core...

Fig. 7. (a) Crystals of E. colt 70 S ribosomes, (b) and (c) Electron micrographs of sections through three-dimensional crystals shown in (a) in two orthogonal directions (Wittmann et al., 1982). (d) and (e) Crystals and computed filtered image of a section through a crystal of Bacillus stearothermophilus 50 S ribosomal subunits (Yonath et al., 1982a,b Leonard et al., 1983). (d) and (e) are related to two different crystal forms. Reproduced with permission from Wittmann (1983). 

Fig. 14 Scanning electron microscopy images of the silica-based MIP monolith cross-section of the formed monolith magnified (a) 800x and (b) 5,000 x. Reproduced with permission from [184]...

In an electron microscope, a stream of electrons is formed by the electron source and is accelerated toward the specimen using a positive electric potential. The stream is focused into a thin, monochromatic beam by using metal apertures and magnetic lenses. The electron beam interacts with the specimen and the effects of these interactions are detected and transformed into an image. 

Figure 10.4 Electron microscope image of negatively stained amyloid fibrils formed by islet amyloid polypeptide showing long, unbranching fibrils of 100 A in diameter (reproduced with permission from [4]).

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