[en] The system of relativistic equations that was considered by H.A. Buchdahl and V. Wuensch has been derived for bosonic fields with nonvanishing rest mass by the help of a variational principle. Because of the integer spin s ≥ 1 of the considered particles the underlying Lagrangian and the field equations can be represented in tensor language. The energy-momentum tensor belonging to the field is computed by variation of the metric. (author)

[en] For the precise X-ray spectroscopy with crystal diffraction spectrometers it is necessary to stabilize the temperature on the analyzer crystal. The structure, operation and first results of a discontinuous optimized controller which solves this problem are presented. At the crystal a long-time maximum temperature constancy of ± 0.04 K was obtained. (author)

[en] A simple X-band cavity for electron-nuclear-nuclear triple resonance (Double ENDOR) experiments in solids is described. Inside a rectangular H₁₀₂ cavity two flat coils are placed in the plane in which the electrical microwave field is zero. Due to the small diameter of the coils sufficient rf fields for saturating the NMR transitions are generated by rf powers of 20 W. The efficiency of this simple cavity is shown by different instances (determination of signs of the coupling constants, nuclear spin decoupling in ENDOR). (author)

[en] Starting from a general relativistic material theory developed by M.N. Polosow and the author, the influence is studied of the gravitational field on some well-known electromagnetic phenomena in GRT. Additionally, new effects occur in fluids, caused by an anisotropy which is due to a gravitational field. For example, in a Schwarzschild field a fluid has the same optic properties as a crystal with one axis. The relative difference of the indices of refraction for the ordinary and the extraordinary ray Δn/n is of the order 1.17 x 10^-10 on the earth's surface. (author)

[en] The N-fold Baecklund transformation for a class of nonlinear differential-difference equations is derived and used to construct N-soliton solutions. (author)

[en] Laser-induced diffusion of vacuum-evaporated aluminium films onto n-type Si substrates is applied to produce locally p⁺n junctions using a nitrogen pulse laser with 3 ns pulse duration (lambda = 337.1 nm). The average laser power reaching the targets is (3 - 5) x 10⁵ W. The resulting Al-Si alloy junctions are investigated by SEM (EBIC and SE voltage contrast) and I-V measurements. Irradiations are performed by single laser pulses in the range of energy densities between E/sub d/ = 1.0 J/cm² and 6.0 J/cm² in air at room temperature leading to an inhomogeneous lateral and spatial distribution of the Al doping concentration. For E/sub d/ = 4.1 J/cm² and an Al surface layer of 40 nm on low resistivity n-Si material (rho = 3 - 5 Ω cm) Al-nSi alloy diode can be produced by local melting having reverse currents of 3 x 10^-7 A at a reverse voltage of V/sub r/ = 1 V. EBIC studies on bevel faces of such laser-doped diodes reveal that the alloyed junctions penetrate into the depth of the n-type substrate between 0.8 and 4.5 μm dependent on E/sub d/. (author)

[en] By means of precise experiments and appropriate techniques of data evaluation small-angle X-ray-scattering experiments allow a determination of the second order derivative of the correlation function γ₀''(r) of the respective sample. Thus the intercept distribution density function is useful for studying how the intensity of small-angle X-ray scattering is affected by the shape of the particles (phases) as well as for studying the phases in the techniques of IUR-line analysis in a multi-phase system. The densities A(l) differ very much from each other and have various characteristic features. In this work the function A(l) of a parallelepiped is given in an analytical compact form. The result can be specialised to a cube, to a bar with rectangular cross-section or to a rectangular laminar plate and to a segment of length l. General properties of A(l) at l = 0 are given. (author)

[en] The determination of concentration dependent diffusion coefficients D(c) is possible, if two concentration profiles in a solution at short time distances are recorded by means of the Raman spectroscopic method. D(c) is elegantly obtained by application of the Boltzmann transformation in connection with Fick's second law. (author)

[en] Tomographic experiments on the basis of a 60 MHz solid state NMR spectrometer and a 8 bit home-built microcomputer are described. The projection reconstruction method was used for computing image matrices of the dimension (64,64). Results of a computer simulation and measurements of a water phantom are presented and discussed. (author)

[en] The population of water fractions (liquid phase and macromolecular bound phase) in wheat grains was investigated by separation of the NMR-signal components characterized by different spin-spin relaxation times. The state of the bound water (hydration water) was studied by analyzing the spin-spin and spin-lattice relaxation times in dependence on water content. Results are discussed in terms of a continuous distribution of the bound water correlation times. In the range of investigated water content (f approximately 6 - 18%) bound water is dominating. The signal intensity of the liquid component remains constant until f approximately 13%. At higher water content the liquid fraction increases too. One possible conclusion is that bound water changes the conformations of macromolecular structures with increasing water content. Such a way the conditions for storing of liquid water and for active biological function of biomolecular structures may be produced. (author)