Abstract
The prevailing majority of EPR spectra in solid samples concern the randomly oriented paramagnetic particles in solids (polycrystalline samples, powders, glasses, ceramics, frozen solutions). In these cases it is necessary to provide numerical simulation or nonlinear optimization of the spin-Hamiltonian parameters to obtain the relevant physical results. The presence of various paramagnetic particles in the same sample often complicates the situation. This paper deals with the numerical solution to these problems. Illustrative examples of EPR spectroscopy of radiation-induced paramagnetic centers in glasses and EPR of Cu(II) as a spin label in the study of the thermal evolution of SiO2gel preparation are also presented.