Studies of the properties of runaway electron preionized diffuse discharges (REP DDs) and their possible use have been carried out for more than 15 years. Three experimental setups generating a low-temperature atmospheric-pressure plasma and differing in the geometry of a discharge gap were developed. They allow the treatment of surfaces of different materials with an area of several tens of square centimeters. A diffuse discharge plasma was formed in the pulse–periodic mode by applying negative voltage pulses with an amplitude of several tens of kilovolts and a duration of 4 ns to a discharge gap with sharply non-uniform electric field strength distribution. This paper presents experimental results of the study of the surface layer microstructure of copper and steel specimens of different sizes after treatment with the REP DD plasma in nitrogen flow mode and nitrogen circulation mode in the discharge chamber. It was shown that after 10⁵ discharge pulses, the carbon concentration decreases and a disoriented surface layer with a depth of up to 200 nm is formed. Moreover, the results of X-ray phase analysis did not reveal changes in the phase composition of the surface of copper specimens. However, as a result of surface treatment with the REP DD plasma, the copper lattice becomes larger and the microstress increases.

The effect of modification of MFI zeolite 1–5 wt.% ZnO activated by plasma on acid and catalytic properties in the conversion of the propane–butane fraction into arenes was investigated. The high-silica zeolites with silicate module 45 were synthesized from alkaline alumina–silica gels in the presence of an ‘X-oil’ organic structure-forming additive. The modification of the zeolite with zinc was carried out by impregnating the zeolite granules in the H-form with an aqueous solution of Zn(NO₃)₂. The obtained zeolites were characterized by X-ray phase analysis and IR spectroscopy. It is shown that the synthesized zeolites belong to the high-silica MFI zeolites. The study of microporous zeolite-containing catalysts during the conversion of C₃-C₄ alkanes to aromatic hydrocarbons made it possible to establish that the highest yield of aromatic hydrocarbons is observed on zeolite catalysts modified with 1 and 3% ZnO and amount to 63.7 and 64.4% at 600 °C, respectively, which is 7.7–8.4% more than on the original zeolite. The preliminary activation of microporous zeolites modified with 1–5% ZnO and plasma leads to an increase in the yield of aromatic hydrocarbons from the propane–butane fraction; the maximum yield of arenes is observed in zeolite catalysts modified with 1 and 3% ZnO and activated by plasma, amounting to 64.9 and 65.5% at 600 °C, respectively, which is 8.9–9.5% more than on the initial zeolite. The activity of the zeolite catalysts modified by ZnO and activated by plasma show good agreement with their acid properties. Activation of the zeolites modified by 1 and 3% ZnO and plasma leads to an increase in the concentration of the weak acid sites of the catalyst to 707 and 764 mmol/g in comparison with plasma-inactivated 1 and 3% ZnO/ZKE-XM catalysts at 626 and 572 mmol/g, respectively.

We presented the results of a study on the spectra of photo-, cathodo-, and X-ray luminescence of diamond samples obtained by the temperature gradient method and subjected to radiation-thermal treatment. It is shown that cathodoluminescence can be used as a rapid method for determining the impurity-defect composition of crystals. Photoluminescence allows for the localized excitation of defect centers in the crystal. X-ray luminescence proved to be the least informative in terms of determining the defect composition; however, the conducted studies demonstrated that diamond samples containing NV⁰ centers can be used as visualizers of synchrotron beams.

Subject of study. Synthetic diamond samples fabricated under high-pressure and high-temperature conditions, then subjected to radiation-thermal treatment to obtain no more than 10 ppm of NV ⁰ centers are studied. Aim of study. The aim of this study is to experimentally investigate the spectral characteristics of cathodoluminescence (CL) in synthetic diamond samples at temperatures of 90–800 K. Method. The luminescence of synthetic diamonds was studied using spectroscopic methods. Main results. The CL spectra of three diamond samples at temperatures of 90–800 K were investigated by exciting CL using an electron beam with an energy of up to 300 keV. The temperature dependences of various color centers were obtained, and an anomalous temperature dependence of the 3H center luminescence was observed, which is likely associated with thermally stimulated luminescence. Practical significance. The luminescence centers identified in the synthetic diamonds evaluated in this study provide a basis for developing various optoelectronic devices, such as thermally stimulated and cathodoluminescent dosimeters.