Investigations of Sb-based chalcogenides, stephanite Ag₅SbS₄ and bournonite CuPbSbS₃, have been performed by ^121,123Sb nuclear quadrupole resonance (NQR). In stephanite a phase transition at 140 K and internal diffusion motions with an activation energy of 0.29 eV have been experimentally detected. The analysis of experimental results for bournonite revealed two crystal-chemical positions of Sb in the unit cell with distinct local symmetry. The NQR frequencies ν and line-widths Δν data indicate that Sb(A)S₃ complex has almost axial symmetry, but Sb(B)S₃ complex is substantially distorted.

A series of nanosized (20 nm and larger) samples of hydroxyapatite powders synthesized by wet preparation method and doped with Mn²⁺ and Pb²⁺ ions were studied by 94 GHz pulsed electron paramagnetic resonance (EPR). The results are compared with those obtained in the samples of aorta walls from male patients with atherosclerosis as well as in bulk hydroxyapatite materials. It is shown that in contrast to bulk materials Pb ions at least partially replace the Ca(1) site in the hydroxyapatite structure. The spectral characteristics of the Mn²⁺ ions revealed in atherosclerotic plaque and synthetic hydroxyapatite are found to be practically identical. The hypothesis about the important role of (nano)hydroxyapatite in formation and rupture of atherosclerotic plaques is supported.

High-resolution proton NMR (400 MHz) and multifrequency EPR (9 - 260 GHz) characterization of aqueous solutions of the nitroxyl radical TEMPOL in the temperature range (10 - 40) °C is performed for the liquid-state DNP. Characteristic features of the in-situ DNP observations at high frequencies are presented. Optimal conditions (concentration, temperature, position of the microwave pumping, repetition/build-up time for the DNP experiments) are extracted. The results are compared with the DNP experiments, molecular dynamic calculations, saturation models, and classical models of translational and rotational diffusion. Perspectives for using TEMPOL as polarizing agent in even higher magnetic fields are discussed.

The home-built pulse nuclear magnetic resonance spectrometer for ³He research is described. The temperature range is 1.5 - 4.2 K, the frequency range is 3 - 20 MHz, the dead time is 10 μs at 10 MHz. The spectrometer software is based on programming language LabVIEW. The advantages of digital technique are described; particularly the implementation of digital quadrature detector.