Die aktivierungsanalytische Bestimmung von Verunreinigungen in Uranverbindungen nach papier-chromatographischer Abtrennung des Urans

Ohne Zusammenfassung     

Time-dependent electric quadrupole interactions in (NH4)3HfF7

Spinrotation spectra of polycrystalline (NH₄)₃HfF₇ in which radioactive¹⁸¹Hf was incorporated have been measured in the temperature range from ?196 °C to + 70 °C. The spectra were interpretated on the base of the stochastic model of M. Blume. It was assumed that reorientations of the [HfF₇]^3? polyhedra take place at random. The resulting fluctuation rates can be understood as to be caused by an activation process. The activation energy was determined to 0.324(12) eV in agreement with NMR measurements on¹⁹F in this compound.     

The Chemical Behavior of Active Nitrogen

Active nitrogen, which is formed on passage of an electric discharge through a stream of nitrogen, is detected by a characteristic yellow afterglow. It can be determined quantitatively, e.g. by gas phase “titration” with nitric oxide. Active nitrogen reacts with many chemical elements, as well as with organic and inorganic compounds. Although nitrogen atoms are responsible for many of the reactions of active nitrogen, electronically excited molecules also play a role.     

Influence of mechanical surface treatment on the hysteretic behaviour of type II superconductors in the mixed state

It is experimentally shown, that mechanical roughening of the surface of Nb-cylinders leads to a hysteretic behaviour of magnetization in an applied magnetic field. Hysteresis is caused both by trapping of flux vortices near the surface and by induced persistent surface currents.     

Generalized Brownian Motion,Point Processes and Stochastic Calculus for Random Fields

A representation of the Malliavian derivative and the Skorochod integral in terms of random point systems on Polish spaces (and thus generalizing from the unit interval) is derived. This leads to a stochastic calculus based on random point systems. The operators are given explicitely and in a simple form allowing concrete probabilistic and quantum probabilistic interpretations.     

On the Relaxation of Energetic Electrons in Plasmas

The impact of individual collision processes on the relaxation of the velocity distribution function of a group of electrons, initially localized in a narrow region at relatively high energies, has been studied. By having recourse to solutions of the non-stationary Boltzmann equation and to corresponding Monte-Carlo simulations, the temporal behaviour of electrons in CO₂ plasmas, both in the absence and the presence of an external dc field, has been investigated. A microphysical interpretation of observed relaxation phenomena, based on the data relevant to the individual collision processes, is also given.     

Strict Kinetic Treatment of the Electron Response to Spatial Field Disturbances in Nonequilibrium Plasmas

In generalization of former approaches for the simplified solution of the inhomogeneous electron Boltzmann equation a higher order solution technique has been developed. This technique is based on a multi-term expansion of the electron velocity distribution function and allows a strict study of the electron kinetics in plasmas acted upon by space-dependent electric fields. This solution technique is used to investigate the response of the plasma electrons to spatially limited disturbances of the electric field in weakly ionized plasmas of helium and mercury. By solving the kinetic equation with increasing order of the multi-term expansion the convergent solution of the kinetic problem and thus the strict spatial behaviour of the velocity distribution and of significant macroscopic properties of the electrons has been determined and analysed. Furthermore, the impact of higher order terms of the expansion has been revealed and the falsification of the velocity distribution and of related macroscopic properties has been evaluated when instead of the multi-term solution the simpler two-term solution of the kinetic equation is used.