Structural Research / Strukturforschung (1957) (Handbuch der Physik Encyclopedia of Physics: 6 / 32)

By: Dr. André Guinier and Dr. Gérard Eller and Dr. J. Bouman and Dr. Gérard Fournet and Professor Dr. Beeman and Professor Dr. Kaesberg and Dr. J. Anderegg and Dr. M. Webb and Professor Dr. Raether and Dr. G. Ringo

Sign Up Now! Already a Member? Log In
You must be logged into UK education collection to access this title. Learn about membership options, or view our freely available titles.

Synopsis: 107 In this way the absolute values of the structure factors may be found, not the phases (6. 8). The problem to find these phases is the phase problem. The present article will treat the following topics. At first the description of the ideal crystal will be given in Chap. B. The underlying principles of this description are the concepts of reciprocal lattice, FOURIER synthesis and sym metry. The evaluation of the intensity will then follow in Chap. C and D. Chap. E is concerned with the phase problem and related topics. Though this article treats the analysis of crystal structures, the fundamental concepts for other structures will here be found too. But these topics, and the experimental methods, will l find their place elsewhere . B. Description of the crystalline state. I. Lattice theory. a) The direct lattice. 8. Introduction. In Sect. 3, a description of the ideal crystal was given: The space, occupied by a crystal, is divided into congruent parallelepipeds, each with the same orientation. This parallelepiped is defined by the three basic vectors, a, band c, drawn from an origin 0 (Fig. 2), and is called the primitive cell. This cell is filled with atoms (or ions), and the same configuration of atoms is repeated in space. It has been aptly called a three-dimensional wallpaper, as on a wallpaper the same pattern is repeated again and again.