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Amplification of a dosimetric EPR signal in mineralized biological materials available in limited quantities has been demonstrated in this paper. Powders of irradiated enamel, dentin, and bone tissue were placed into silica ampoules with the outer diameter close to 1.4 mm. To amplify the signal, the dielectric insert in the form of cylinder with the outer radius 2.85 mm, the inner radius 0.75 mm, and the height 1.85 mm made of a high-κ and low-loss ceramic material BaTi4O9 + 8.5% ZnO has been used. It has been shown that maximum signal amplification (about an order of magnitude) has been achieved when the sample is completely inserted into this dielectric. It has been found that the line shape of the dosimetric signal is not distorted, if using the dielectric insert. Decomposition of the amplified EPR spectra allowed us to determine the relative contribution of two types of CO2- radicals to the dosimetric signal, which coincides with the literature data. [ABSTRACT FROM AUTHOR]

Four ZnS nanopowders containing an uncontrolled impurity of manganese were studied using EPR technique. The powders with the average sizes (6...8 nm) were synthesized by either joint or sequential decomposition of diethyldithiocarbamate complexes of zinc and europium in high-boiling solvents at various temperatures. All samples demonstrated the EPR signal that is not typical for ZnS powders with µm-sized particles. Computer simulation showed that EPR spectra of all the samples could be fitted by two components. The first component with g = 2.0022 ± 0.0002, (63.5 0.5) 10-4 cm-1 A = - ± × , 0 4 1 4 3.5 10 cm- - b × was assigned to Mn2+ ions in the cubic surrounding, Mn(C). The parameters of the second component were g = 2.0022 ± 0.0002, (63.5 0.5) 10-4cm-1 A = - ± × , 0 () 4 1 2 36 1 10 cm- - b = - ± ×; this component was attributed to Mn2+ ions associated with a planar lattice defect (stacking fault), Mn2+(D). The ratio of centers amounts Mn2+(C)/Mn2+(D) for the samples studied was 2.1/1 (in the samples 1 and 4) and 1.7/1 (in the samples 2 and 3), respectively. EPR of Mn2+ ions was shown to be an effective method for detecting planar lattice defects in ZnS nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract. Colloidal undoped CdS and doped CdS:Mn nanoparticles were synthesized in the solution of polyvinyl alcohol polymer, and the process of nanoparticles growth was monitored by optical absorption measurements. The inclusion of Mn 2+ impurity was checked by electron paramagnetic resonance measurements. It is shown that the core of CdS:Mn nanoparticle is undoped. The results obtained demonstrated that the rate of the band gap value decrease during nanoparticles growth is slower for the Mn-doped nanoparticles as compared to the undoped ones. This effect was ascribed to the inhibition of nanoparticles growth in the solution containing manganese salt. The model of the adsorptive doping of CdS NPs with manganese was proposed. [ABSTRACT FROM AUTHOR]