Reciprocal lattice indexing rotation photographs

Indexing rotation photographs by reciprocal lattice methods. Orthorhombic crystals. First of all, the coordinates and for each reflection on the photograph (Fig. 86) are found in one of the ways just described these coordinates may be plotted as in Fig. 87 a to form the reciprocal lattice rotation diagram. The problem now is to decide which point of the reciprocal lattice itself corresponds to each spot on the rotation diagram. 

Indexing rotation photographs by reciprocal lattice methods. Orthorhoml jc crystals 162... 

From a comparison of various spot electron diffraction patterns of a given crystal, a three-dimensional system of axis in the reeiproeal lattice may be established. The reeiproeal unit cell may be eompletely determined, if all the photographs indexed. For this it is sufficient to have two electron diffraction patterns and to know the angle between the seetions of the reeiproeal lattice represented by them, or to have three patterns which do not all have a particular row of points in common (Fig.5). Crystals of any compound usually grow with a particular face parallel to the surface of the specimen support. Various sections of the reciprocal lattice may, in this case, be obtained by the rotation method (Fig.5). 

Fig. 7.7. The relation between cyhndrical coordinates and indices of reciprocal lattice. Points of rotation photograph (indexing of rotation photographs)...

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