Note on the theory of solutions of strong electrolytes

Summary In the general case, assumptions of an increase in the average diameter of ions and hydration numbers with temperature contradict experiment. To explain the positive deviations of experimental heats of dilution from the Debye-Hückel theory, it is necessary to consider the existence of ionic pairs in solution and changes in the solution structure with concentration.     

The diffusion coefficient of zinc in NaCl crystals

Measurements of the temperature and concentration dependence of the diffusion coefficient of divalent zinc were made to explain the mechanism of the process and to check the current theoretical conception. The measurements were executed on pure NaCl crystals. A knee in the curve of the logarithm of the diffusion coefficient versus the inverse temperature shows the diffusion is connected to two processes of different activation energy in accordance with the theoretical conception. The theoretically expected concentration dependence, however, has not been found, nor does the knee correspond to the expectations.     

The influence of screening on Mott scattering by mercury atoms

Zeitschrift für Physik A Hadrons and nuclei - Cross sections of elastic electron scattering by mercury nuclei have been measured at energies and angles where the screening of the nuclear...     

Zum Beugungswirkungsgrad von Volumenhologrammen. Teil II. Reflexionshologramme

In this paper we give an exact solution of the coupled differential equation system as developed by Kogelnik [1] for the case of symmetrical recording without neglecting the second differentials for the reflection volume hologram. This solution is applicable to dielectric, absorption and so-called mixed volume holograms. There are some remarkable distinctions between our results and those got by Kogelnik for the case of absorption and mixed holograms. It is shown, that under special assumptions and approximations or for special combinations of the material parameters we get the same relations as Kogelnik.     

Zur Deutung der Struktur der Bremsstrahl-Isochromate des Wolframs an der kurzwelligen Grenze

Ohlin's maximum of the tungsten isochromat may well be explained on the basis of the energy bands of tungsten calculated byManning andChodorow. The photons near the threshold voltage are then assumed to arise from transitions of the primary electrons to the unoccupied levels of the 5d and 6s bands. Using this explanation one has to drop, however, a selection rule formulated byNijboer, admitting only transitions to final s states. The validity of this ?s selection rule“ is critically examined. For a strict treatment one has to calculate the matrix elements connected with the transitions, using the exact wave functions of the tungsten crystal. These, however, are not known sufficiently. ThereforeNijboer appliedNedelsky's results for free-free transitions at the isolated atom to the transitions to bound states of the solid. Yet according to calculations made recently byGuggenberer the s selection rule is put into question even for free-free transitions. — A better approximation is obtained considering electron transitions from the continuum to the 5d and 6s states of the isolated atom. A calculation of the corresponding matrix elements is carried out. It shows that both kinds of transitions are of about the same probability at energies around 1 keV which are of special concern to us. Therefore it is allowed to use the 5d band for explaining the tungsten isochromat.