Rotating and Oscillating Crystal Methods

The arrangement for taking rotating crystal photographs differs from that for powder photos in three important respects (a) only one crystal 

The processes by which indices are assigned to each of the individual spots in a rotation photo cannot be described here. However, the separation of reflections into layer lines should, at least in principle, make such an assignment far easier than identification of the lines in powder photos. If, for instance, the crystal has been rotated about its a axis, all reflections on the zero th layer line will have indices of the type (0, k, Z), whereas 

But even in a rotation photo there may be a hundred or more spots packed together in each of the layers, and indexing such spots is practically never attempted. Instead, photos are taken, one layer at a time (that is, every layer except one blocked out by a metal screen). At the same time the film is moved as the crystal is rotated and the various spots in each layer fall upon a series of arcs. Such photos (Weis-senburg pictures) are indexed with ease. 

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G,5 M. J. Buerger. X-Ray Crystallography (New York Wiley, 1942). Theory and practice of rotating and oscillating crystal methods. Space-group theory. 

G.8 N. F. M. Henry H. Lipson and W. A. Wooster. The Interpretation of X-Ray Diffraction Photographs (London Macmillan, 1951). Rotating and oscillating crystal methods, as well as powder methods, are described. Good section on analytical methods of indexing powder photographs. 

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