The angular variation of V⁴⁺ electron paramagnetic resonance (EPR) line positions were recorded in single crystals of β-Mg₂V₂O₇ and α-Zn₂V₂O₇ at 120 K and 295 K in three mutually perpendicular planes in the temperature range from 120 to 295 K and at some intermediate temperatures. Least-squares fitting was used by diagonalization of the Spin-Hamiltonian (SH) matrix to determine the SH parameters and the orientations of the principal axes of the g- and A-matrices from the angular variations of the EPR line positions. Although the V⁴⁺ SH parameters were found to be similar in the two crystals, the orientations of the principal axes of the g- and A-matrices were not found to be coincident in the two crystals.

Molecular mobility and exchange of adsorbed fluid in porous media of silicalite-1 were studied by two-dimensional nuclear magnetic resonance (NMR) techniques in fully and partly saturated samples. Three porous volumes were determined in silicalite-1 where n-hexane and water molecules are adsorbed: intracrystallite channels, mesopores and intercrystallite space. The molecular exchange between all porous volumes was observed and typical exchange times were estimated for n-hexane and water. Using the exchange times the self-diffusion coefficients were estimated as D ~ 1.11×10⁻¹⁰ for n-hexane and D ~ 6.67×10⁻¹¹ m²/s for water in fully saturated silicalite-1 and found in a good agreement with literature data.

We report systematic detailed measurement of the superconducting properties on the layered organic superconductor κ-(BEDT-TTF)₂Cu[N(CN)₂]Br near 80 K and the effect of disorder on the superconducting transition temperature T_c. The reversible part of the magnetization (reversible magnetization) and the magnetic entropy change (ΔS) were studied. Using the London model, we determine the temperature dependence of the London penetration depth (λ) from the slope of the linear M(lnH) dependence of the isothermal magnetization. Our results show the strong dependence of ΔS and λ on the temperature. The structural transformation which occurs at the vicinity of 80 K very strongly influences the physics of vortex lattice and the associated magnetic behavior.

The detailed calculations of dependence of the frequency of oscillations on the external magnetic field and on the shape of ferromagnet sample with interacting electronic and nuclear subsystems were done. Such system possesses a discrete number of eigenfrequencies of precession of magnetization. It is shown that these magnetostatic eigenmodes can be degenerated, i.e. different modes can have the same frequency. The dependence of these degenerated modes on the sample shape is investigated. It is shown that the properties of magnetization precession and even the number of eigenmodes depend on the external magnetic field and on the shape of the sample. These effects may produce specific features on the NMR spectra of magnetic materials.

The expressions for calculating the matrix elements of the Coulomb interaction between an electron and a low-symmetry infinite crystal lattice have been obtained. One-center matrix elements are considered. The Gaussian type of orbitals (GTO) is used in calculations. All expressions are absolutely and rapidly converging series in the space of reciprocal lattice vectors.