Gold crystals, diffraction patterns

FIGURE 1.21 Davisson and Germer showed that electrons produce a diffraction pattern when reflected from a crystal G. P. Thomson, working in Aberdeen, Scotland, showed that they also produce a diffraction pattern when they pass through a very thin gold foil. The latter is shown here. G. P. Thomson was the son of J. J. Thomson, who identified the electron (Section B). Both received Nobel prizes 1.1. for showing that the electron is a particle and G. P. for showing that it is a wave. 

Figure 8. Image and diffraction pattern from an (100) epitaxial. specimen of gold prepared in an unbaked UHV evaporator by depo.sition onto KOI and then transfer onto amorphous carbon. Here water vapour was the dominant residual gas (determined by mass spectrometry). The particles are square pyramidal single crystals.

FIG. 20-24 High -resolution TEM image of Si nanowires produced at 500 C and 24.1 MPa in supercritical hexane from gold seed crystals. Inset Electron diffraction pattern indexed for the <111> zone axis of Si indicates <110> growth direction. [Reprinted with permission from Lu et al. Nano Lett., 3(1), 93-99 (2003). Copyright 2003 American Chemical Society. ]... 

Fig. 4 Transmission electron micrographs of a highly facetted mostly triangular gold particles, b a hexagonal particle, c electron diffraction pattern of the triangular particle showing that it is a single crystal. Diffraction from the (111), (220), (311), (331), (422) planes are identified...

The organic matrix follows the same pattern. By means of electron diffraction analysis it can be shown that the protein matrix is and remains crystalline and that the structural order of the diffraction pattern is that of a microcrystalline film of gold (Fig. 23)224). It is remarkable that the matrix proteins in other species also produce a single crystal spot pattern. This implies that isolated pieces of organic matrix which are in the order of a few microns thick represent single crystals. Whatever the term single crystal" may mean to the various researchers43, in the context... 

F re 3.1 (a) A spot diffraction pattern from a single crystal of gold (b) A ring... 

Importantly, the calculated diffraction pattern is not affected by the typical sources of errors of experimental powder diffraction (preferential orientation, mixtures, presence of amorphous phase) that often complicate or render uncertain the interpretation of measured powder diffractograms hence the calculated powder pattern is often referred to as the gold standard pattern for a crystal form. 

---