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.

Inhalt
Inhalts verzeichnis.- Les méthodes expérimentales des déterminations de structures cristallines par rayons X.- A. Les apparails de la radiocristallographie.- B. Du diagramme au réseau réciproque.- C. Du réseau réciproque à la structure.- D. Applications des méthodes radiocristallographiques.- Bibliographie générale.- Theoretical Principles of Structural Research X-rays.- A. Fundamental concepts in structure analysis.- B. Description of the crystalline state.- C. The fundamental concepts in X-ray scattering.- D. The intensity of the diffracted X-rays.- E. Problems of structure analysis.- General references.- Etude de la structure des fluides et des substances amorphes au moyen de la diffusion des rayons X.- A. Théorie de la diffusion des rayons X par les fluides.- B. Etude expérimentale de la diffusion des rayons X par les fluides.- C. Etude des substances amorphes.- Bibliographie générale.- Size of Particles and Lattice Defects.- A. Size and shape of particles from small angle x-ray scattering.- B. Lattice defects.- Elektroneninterferenzen.- I. Aufbau von Interferenzapparaturen.- II. Die Interferenzen der Elektronenwellen.- III. Anwendung der Elektroneninterferenzmethode auf spezielle Probleme.- IV. Beugung der Elektronenwellen.- Zusammenfassende Darstellungen.- Neutron Diffraction and Interference.- I. Introduction.- II. Theory of the scattering of thermal neutrons.- III. Experimental techniques.- IV. Measurement of nuclear properties by use of neutron optics.- V. Determination of the structures of non-magnetic materials by neutron diffraction and refraction.- VI. Studies of magnetic materials by neutron diffraction and refraction.- General references.- Sachverzeichnis (Deutsch-Englisch).- Subject Index (English-German).- Table des matières (Français).