Schraubenversetzungen in zylindrischen Körpern

The stress field and the energy of straight screw dislocations lying parallel to the axis of cylindrical specimens with various cross sections are calculated. The method employs results of the theory of complex functions. An extension of the isotropic theory to dislocations in the hexagonal basal plane is given. The application of the method to dislocation configurations observed in the electron microscope is described. Finally the connection with the method of image dislocations is discussed.     

Röntgenstreuung in Körpern mit regelloser Struktur

It is shown how small angle scattering can be used to get information on the gross structure of a medium with non-crystalline matter distribution. Explicit formulae are derived for the special case of a gel with hole structure, where X-ray analysis will be appropriate. The scattering intensity is expressed in terms of a correlation functionC (r) which determines, byC′(0), the specific surface of the gel. If the hole sizes are random, the correlation function takes on the analytic form of a simple exponential, containing a correlation length a. This correlation length can be measured directly by observing the angular distribution of the scattering intensity.     

Die Sichtbarmachung der stehenden Ultraschallwellen in durchsichtigen festen Körpern

Zeitschrift für Physik A Hadrons and nuclei - Die stehenden Ultraschallwellen in festen Körpern werden zunächst in einem Piezo-Quarz optisch abgebildet. Der Streifenabstand im Quarz...     

Kontrastreiche und von Aufladungsstörungen freie Abbildung hochisolierender Oberflächen mittels Sekundärelektronen

The apparent secondary electron yield from metal surfaces (Au, W, Al, Zn, Ag, Ni and Cu) with a polymeride layer of varying thickness was measured. It was found that even with a layer thickness of as much as 40 Å and a primary energy of 25 kev there were clearly noticeable differences in emission from the various substances. This effect can be used for the electron emission microscopy of specimens consisting of insulating materials. In some cases, satisfactory images of such specimens could not be obtained in a reproducible way if other methods, e.g. Cevales' partial evaporation method were applied. If a carbon layer 30 Å in thickness was evaporated onto the insulating specimen surface byBradley's procedure, well contrasted images free from disturbances by surface charges could be obtained from specimens such as glass, thermally etched A1₂O₃ and other minerals. In these images, a resolution limit of 800 Å was attained.     

Elektrische Leitungsphänomene in anisotropen Medien. IV

Another model for the interaction between electrons and phonons, depending explicitely upon the wave vectorsk andk′, is discussed with respect to its influence on galvanomagnetic effects. From the models handled in II it differs mainly in the temperatur coefficients.