Vol 57, No 2 (2023)

Long-lived delayed fluorescence of dispersions of microcrystals of naphthalene–β-cyclodextrin–cyclohexane ternary complexes has been studied. It has been established that the delayed fluorescence is due to the T–T annihilation process. The kinetics of delayed fluorescence has a nonexponential character; the average lifetime is 0.68 s. The shape of the decay rate curves of delayed fluorescence does not depend on the intensity of excitation light. The nonexponential nature of the delayed fluorescence is presumably associated with the presence in the crystals of paired naphthalene molecules with different mutual positions and pair formation energies.

A relation has been established between the decrement of the low-field magnetic spin effect (measured by the luminescence of polymer films of composites with rubrene microcrystals), caused by the addition of magnetic Cu–Ni nanoparticles with a low Curie temperature (TC = 40–60°C), and the photoinduced particle magnetic moment exceeding the dark moment. Based on the study of the temperature dependence of the decrement and its comparison with the thermal demagnetization of the dark magnetic moment, a conclusion was made about a possible mechanism for the photothermal magnetization of nanoparticles

It has been shown that for obtaining hydrophobic coatings, it is reasonable to use fluoroalkylalkoxysilanes (FASs) with a longer fluoroalkyl chain than FAS-19, so that the F/Si molar ratio exceeds 5–6. It is proposed to purposefully change not only the chain length of oligomers, but also the structure of solutions from dilute colloidal solutions to structured gels, with the F/Si ratio being controlled. In the case of polycondensation of investigated fluoroalkylalkoxysilanes on a hydroxylated surface, a strong silicone framework is formed, which is chemically bonded to the surface and to fluoroalkyl chains oriented perpendicular to it

The effect of γ-radiation doses from 100 to 3000 kGy on the toxic properties and germination of oat seeds has been + studied. A tendency has been noted for a 15–25% decrease in the germination of oat seeds under laboratory conditions in the range of presowing irradiation doses of 10–700 Gy. After irradiation with a dose higher than 1 kGy, the seeds lost their ability to germinate. Curves reflecting the dependences of the length of oat stalk on the dose of presowing irradiation of seeds exhibited two areas with a characteristic separation point at doses of 70 Gy, below which the degree of influence of the irradiation dose on the height of
seedlings and their growth ability increased noticeably. The toxicity of radiolyzed oat grains depended on the dose of γ-irradiation of grains and the mode of additional feeding of experimental mice. It was established that a γ-radiation dose lower than 100 kGy did not affect the toxicity of fodder oat grain, and radiation doses of 400 kGy or higher made irradiated grains unsuitable for feeding mice without additional feeding with compound
feed. The higher the dose of γ-irradiation of oat grain, the earlier experimental mice died en masse: after 14–15, 9, 8, and 6 days of feeding at radiation doses of 580, 1000, 1700, and 3170 kGy, respectively. The reason for the toxic manifestation of irradiated oat grains and the death of mice treated with irradiated grain,apparently, can be the formation of toxic substances in oat grains irradiated with high doses due to the occurrence of physicochemical reactions in the course and after irradiation and a decrease in the nutritional value of products associated with the destruction of vitamins and other food components. Intoxication after consumption of oat grains irradiated with a dose of 400–3170 kGy was clinically manifested by depression, lethargy of animals, and signs of dehydration and diarrhea against the background of a strong decrease in the body weight of experimental animals. It is expedient to use radiolyzed oat grains for technical purposes, especially, if they were treated with high doses of radiation

Radiolysis damages the system of conjugated bonds and thus leads to the degradation of the chromophore functions of dyes in aqueous solutions. Ten representatives of quinophthalone, indigo, triphenylmethane, and azo dyes exhibited the same type of correlations between the absorbed dose and the degree of discoloration. It was shown using the method of competing scavengers that the color of aerated solutions decreased mainly due to the addition of OH radicals to the dyes. The radiation-chemical yields of discoloration ranged from 0.03 to 0.11 μmol/J and increased depending on the length of bond conjugation in the dye molecules. For practical electron-beam discoloration of dye solutions with a concentration of 20 mg/dm3, an
absorbed dose of 1–1.5 kGy was sufficient.

The influence of the mixture composition on the electrophysical parameters and plasma emission spectra of mixtures of tetrafluoromethane and trifluoromethane with nitrogen under dc glow discharge conditions has been analyzed. It has been established that the reduced electric field strength changes nonlinearly with an increase in the proportion of the second gas in both mixtures. The reduced intensity of atomic fluorine emission in the CF4/N2 mixture is shown to pass through a maximum at a nitrogen volume fraction of 0.2, whereas a monotonic change in this dependence is observed for the CHF3/N2 mixture. The reduced emission intensities of CF2 radicals decrease monotonically with an increase in the nitrogen fraction in both mixtures.

Проведен анализ влияния состава смеси на электрофизические параметры и спектры излучения плазмы трифторметана с кислородом и аргоном в условиях тлеющего разряда постоянного тока. Установлено, что приведенная напряженность электрического поля нелинейно изменяется с увеличением доли второго газа в смеси. Показано, что при доле кислорода 0.5 в смеси приведенная интенсивность излучения атомарного фтора проходит через максимум, в смеси с аргоном – возрастает и в диапазоне 0.2–0.8 практически не изменяется. В смеси с кислородом наблюдается резкий спад приведенной интенсивности излучения CF₂ в диапазоне 0.2–0.5, а в смеси с аргоном в диапазоне 0.2–0.5 практически не изменяется.

The applicability of laser ablation of metal targets for obtaining triply charged ions of metal atoms, including low-melting metals, has been experimentally demonstrated. By analyzing the luminescence spectra of a plasma plume during laser ablation of a metal target immersed in superfluid helium, the main channel for the formation of helium ions in plasma at a laser beam power density below the breakdown threshold of the helium medium has been determined. It has been shown that the ionization of helium atoms occurs in two steps, the formation of the HeM3+ ionic complex and the dissociation of the complex via its interaction with a metal atom.

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