Visualizing the internal regularity of crystals

FIGURE 2.1. An electron micrograph of the rhombic form of tobacco necrosis virus/ showing the regular arrangement of spherical particles (molecules) in the crystal and also the formation of crystal faces. In this micrograph the viral particles each have a diameter of approximately 250 A. (Micrograph courtesy R. W. G. Wyckoff.) 

It is now also possible to view individual atoms on the surfaces of crystals. One example is by field-ion microscopy, which was developed by Erwin W. Muller. The first images of individual heavy atoms supported on films of light atoms were produced by the use of a dark-field scanning 

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