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Наночастинки (НЧ) Ag/TiO2 було отримано простим методом хімічного осадження з використанням нітрату срібла та суспензії TiO(OH)2. Частинки срібла осаджували як на поверхні, так і в самих частинках TiO2 в залежності від концентрації Ag. Композити Ag/TiO2 були охарактеризованi рентгенівською дифракцією, просвітлючою електронною мікроскопією, скануючою електронною мікроскопією, раманівською та фотолюмінесцентною спектроскопією. Клітинна життєздатність оцінювалась за допомогою аналізу МТТ (3-(4,5-диметилтіазол-2-іл)-2,5-дифенілтетразолію бромід) після впливу НЧ. Показано оптичну активність Ag/TiO2 зі зсувом моди Еg від 143 до 150 см – 1 та FWHM від 12 до 19 см – 1 внаслідок зменшення кристалітів TiO2. Оптична активність зростає зі збільшенням концентрації Ag до 8 мас. %. У зоні контакту Ag-TiO2 утворюється бар'єр Шотткі, що покращує розподіл заряду і таким чином уповільнює рекомбінацію фотогенерованих електронів та фотогенерованих дірок. Отримані результати свідчать про меншу токсичність НЧ у суспензії гліцерин + вода, незалежно від введення молекул срібла в кількості 4 або 8 мас. %, їх значення CC50 становили 50 та 3,9-58,5 мкг/мл для клітин MDBK (нирки бика) та MDCK (нирки собаки) відповідно. Натомість НЧ TiO2, розчинені в C2H5OH+ 1,3-пропандіолі при введенні молекул срібла, були значно більш токсичними для клітин MDBK у порівнянні з чистим TiO2, їх значення CC50 становили 6,5 та 4 мкг/мл. Одержані НЧ Ag/TiO2 внаслідок їх оптичної активності будуть досліджені як протигрибковий матеріал для інгібування бактерій та вірусів у воді. Ag/TiO2 nanoparticles (NPs) were prepared by a simple chemical deposition method using silver nitrate and suspension of TiO(OH)2. Silver NPs were deposited on the surface and inside of TiO2 NPs depended on the Ag concentration. The Ag/TiO2 composites were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy. The cell viability was assessed using an MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay after NPs exposure, since only viable cells have functional mitochondrial dehydrogenase enzymes that can reduce MTT to formazan. The shift of the Eg mode from 143 to 150 cm – 1 and FWHM from 12 to 19 cm – 1 was stated due to a decrease in TiO2 crystallites. Optical activity increased after loading with Ag because metal particles offered electron traps to reduce recombination of holes and electrons, especially Ag loading of 8 wt. %. A Schottky barrier is formed in the Ag-TiO2 contact region, which improves charge separation and thus slows down the recombination of photogenerated electrons and photogenerated holes. The obtained results indicate a lower toxicity of NPs in a glycerin + water suspension, regardless of the introduction of silver molecules in an amount of 4 or 8 wt. %, their CC50 values were 50 and 3.9-58.5 µg/ml for MDBK and MDCK cells, respectively. The obtained Ag/TiO2 NPs due to their optical activity will be examined as an antifungal material for the inhibition of bacteria and viruses in water.

Nanocomposite porous films with silver nanoparticle (Ag NP) arrays were prepared by the pulsed laser deposition from the back flux of erosion torch particles in argon atmosphere on the substrate placed at the target plane. Preparation conditions of the films were set by argon pressure, energy density of laser pulses, their amount and substrate position relatively to the torch axis. The films were prepared with gradient thickness, variable Ag NP sizes and distance between them along the length of substrate as well as corresponding maxima in the spectra of local surface plasmon absorption. Plasmon effects of the Raman scattering enhance in the matter of the Ag NP shell gave the opportunity to register the spectral bands caused by an extremely small quantity of silver compounds with oxygen and carbon. The possible nature of individual bands in the Raman spectrum was analyzed. The obtained results are important for interpretation of the Raman spectra of analytes based on the prepared SERS substrates.

The effect of self-heating on the transport characteristics and electronic properties of transistor AlGaN/GaN heterostructures was investigated. The electrical, micro-Raman and photoluminescence techniques were used for temperature estimations for transistor structures under electrical load. The thermal resistance of these structures has been calculated to obtain the temperature of conducting channel heating from the current-voltage characteristics. The differences in the obtained temperature data from applied techniques have been analyzed.

The simultaneous measurement of Raman and fluorescence signals was proposed to find out the molecule-metal distance. The ratio between Raman and fluorescence intensities was used to estimate molecule-metal distance in nanometer scale. A low-value intensity of the fluorescence of the dye molecules was found using the photobleaching effect. Made was a comparison of experimental results with a theoretical model, which showed well agreement.

The effect of low-temperature annealing on light emitting properties of naSi/SiOx porous column-like nanocomposite films has been studied. Influence of type of chemically active gas or inert ambient on PL characteristics is shown. Existence of metastable defects in such structures is shown. A temperature interval for healing the metastable defects is defined. Mechanisms to reduce a non-radiative recombination channel depending on the gas ambient are proposed.

Using the method of high-resolution X-ray diffraction (HRXRD), we have studied 17-period In₀.₃Ga₀.₇As/GaAs multilayer structure with self-assembled quantum wires (QWRs) grown by the MBE and subjected to postgrowth rapid thermal annealing (RTA) at temperatures (Tann) from 550 to 850 °C for 30 s. It has been shown that the spatial arrangement of QWRs (lateral and vertical) causes the quasi-periodical strain distribution, the strains being essentially anisotropic relatively to crystallographic directions of 〈011〉 type. At Tann ≤ 750 °С, the driving mechanism of structural transformations is relaxation of residual strains due to thermally-activated and strain-enhanced processes of In/Ga atom interdiffusion at the interface QWRs-2D layer, which does not result in considerable changes of the In concentration in (In,Ga)As QWRs. The presence of two superlattice vertical periods in the samples under study and their changes during RTA we explained by an anisotropic character of elastic strain distribution and lowered structure symmetry. The revealed increase in the (In,Ga)As QWRs lateral period caused by RTA is a direct evidence of running lateral mass-transfer processes and can be explained using the model “nucleation plus strain-enhanced In/Ga atom lateral interdiffusion”. At low annealing temperatures, there takes place dissolution of intermediate QWRs as a result of interdiffusion enhanced by residual anisotropic strains. At high RTA temperatures, the interdiffusion process is mainly determined by the composition gradient existing between QWRs and 2D layer.