Wilson A.J.C. X Ray Optics

Methuen & Co. Ltd., 1949. — 127 p.The simpler observations in X-ray crystallography can be treated on the idea that X-rays are reflected from layers of atoms in the crystal, and that the beams reflected by successive parallel layers interfere with one another. This was sufficient, for example, for the interpretation of the early ionization-spectrometer measurements, and of the Laue photographs of simple substances. When more complex crystals were studied some means of exhibiting neatly the information given by the large numbers of spots on moving-crystal and moving-crystal moving-film photographs were necessary, and the device known as the reciprocal lattice was found convenient for this purpose. This device is indeed almost a necessity for the interpretation of such photographs. The reciprocal lattice is not generally familiar, and many books on crystallography stop short at the point where its use becomes desirable. This point is roughly the division between one-dimensional and three-dimensional problems in X-ray optics. Some of the latter problems are treated here : the construction and properties of the reciprocal lattice, its relation to the commoner types of X-ray diffraction photograph, the representation in reciprocal space of crystals that are small, distorted or otherwise imperfect, and the effects of the imperfections on X-ray photographs.