A smoothing method for noisy experimental photoluminescence spectra distorted by narrow spectral peaks and observed in bulk crystals and ZnS:Mn nanocrystals is proposed. The use of this method makes it possible to separate slowly varying components of the photoluminescence spectrum and narrow spectral peaks caused by the radiation of the He-Cd laser plasma or harmonics of the N₂-laser radiation that excite photoluminescence.

The well-resolved terahertz (THz) absorption spectrum of barbituric acid has been investigated using terahertz time-domain spectroscopy. Four distinct THz spectral features and two shoulder peaks were observed in the range of 10-124 cm^-1. A complete analysis was performed with density functional theory, which provided an excellent agreement between solid-state simulation and experiment. The solid-state analysis indicates that the six experimental spectral features observed at low temperature consist of nine infrared-active vibrational modes. Further simulations based on hydrogen-bond isotopologues were performed to study the involvement of hydrogen bonds in the collective modes. A feature at 118.0 cm^-1 mainly stems from the collective vibration of dimer hydrogen bonds (m) while features at 102.0 and 109.6 cm^-1 primarily come from the collective vibrations of linear hydrogen bonds (n). The results may be useful for monitoring molecular reaction in industrial production according to the state of hydrogen bonds.

The principle of operation and features of the oscillating process for a three-wave CO₂ laser with acousto-optic Q-switching are described. Optimization of the composition of the active medium and the conditions of its excitation, as well as the choice of oscillating lines, allow obtaining oscillation with an output power of up to 5 W per line in a stable multi-wave mode. An efficient Q-switching method for a three-wave CO₂ laser is demonstrated, which makes it possible to control the output radiation both in a wide spectral range and in a wide range of modulation frequencies. In order to simplify data acquisition and processing, a method for separating signals with different wavelengths by spacing signals in time has been experimentally implemented using an external selective modulator.

The morphology of two types of emulsions - milk fat in water and liquid paraffin in isopropyl alcohol of various concentrations - was studied by electron spectroscopy in the UV and visible ranges. The developed method is based on the analysis of the scattering component of electromagnetic radiation passing through the sample, which allows determining the size of the scattering particles (droplets) and their size distribution. It was found that particle sizes increase with an increase in the concentration of the dispersed phase. That conclusion was confirmed by independent research methods: dynamic light scattering and optical microscopy.

In space target recognition using spectral analysis technology, there is the problem that the composition or chemical properties of surface materials of the space target are similar. This problem leads to the high similarity of spectral curves and low accuracy of space target recognition. Similar object recognition is important in the study of actual space target observation. In this paper, an entropy weight fuzzy-rough nearest neighbor (EFRNN) algorithm is proposed to enhance the recognition accuracy of similar space targets, which is an improvement of the fuzzy-rough nearest neighbor algorithm. By introducing the feature weight determined using information entropy, the features of all the training samples are considered and quantified. Moreover, the proposed algorithm combined with fuzzy-rough set theory can overcome the fuzzy uncertainty caused by overlapping classes and the rough uncertainty caused by insufficient features, to a certain extent. The simulation results show that the proposed algorithm achieves very promising performance compared with existing algorithms. The EFRNN classifier yields an overall classification accuracy of 95.83%. The proposed algorithm is simple and efficient for similar space target recognition. Furthermore, the EFRNN algorithm does not require preset parameters and complex preprocessing.

Low-temperature photoluminescence was employed to investigate the defects of 4H-SiC crystals after high-energy electron irradiation, and the annealing characteristics and dependence of the detecting temperature and irradiation doses were investigated. Results showed that the emission, associated with carbon antisite-vacancy (V_CC_Si)⁺ defects was dominant in the electron-irradiated 4H-SiC crystal. With increase in detecting temperature, the emission decreased demonstrating red-shifted, and the full width at halfmaximum broadened, which was attributed to the increase in the concentration of carriers arising from thermal activation at high temperature. The emission intensity was the highest value at an irradiation dose of 7.9×10¹⁸ e/cm², and then began to decrease. This revealed the lattice damage caused by long-term high-energy irradiation, which reduced the intensity of the defect radiation in the spectrum.

The decomposition of the IR spectra of kaolin samples after their treatment in the temperature range of 100, 600-1000 °C was carried out by the principal components method. Three main components (PCs) have been identified according to the number of main stages of the structural-phase transformation of kaolinite depending on the processing temperature: dehydroxylation of kaolinite (PC1), transformation of metakaolinite (PC2), crystallization of a new phase (PC3). The samples of kaolin are divided into three groups, according to their factor loads for three PCs. The transformation of metakaolinite was revealed by the change in the coordinates of the frequencies of the IR spectrum for the first and third PCs, to which the bonds (=Al-O) in tetrahedral and octahedral coordination, and the (≡Si-O-Si ≡) bonds (siloxane bridge) are attributed. These bonds are characteristic for amorphous silicate phase. The stages of structural-phase transformations of kaolinite, depending on the processing temperature and the dispersion of the initial kaolin fractions, are in good agreement with the change in the chemical activity of the heat treatment products.

Spontaneous and stimulated emission (SE) of thin Cu(In,Ga)Se₂ films, deposited on sodium-containing glass substrates and irradiated by protons with an energy of 2.5 keV and doses of 10¹⁴—10¹⁷ cm^-2, were investigated upon excitation by nanosecond laser pulses with the power density from 5 to 100 kW/cm². An increase in the intensity and a decrease in the SE threshold appearance were found for the films, irradiated by protons with doses of 10¹⁴—10¹⁵ cm^-2, in comparison with non-irradiated films. An increase in the SE threshold and a decrease in the intensity of SE and spontaneous emission were observed at the irradiation dose of 10¹⁶ cm^-2. After a dose of 10¹⁷ cm^-2 the intensity of emission decreased sharply and the SE threshold was not reached. Possible reasons of the observed effects are discussed.

The spectral-luminescent properties of Er³⁺,Yb³⁺:YMgB₅O₁₀ were investigated. The spectra of the crosssection of absorption and stimulated emission in polarized light were determined. The lifetimes of the erbuim ⁴I_13/2 and ytterbium ²F_5/2 energy levels were measured. The Yb³⁺→Er³⁺ energy transfer efficiency was estimated. Within the framework of the conventional Judd-Ofelt theory the strengths of absorption and emission transitions were calculated, which gave an opportunity to determine the lifetime of the Er³⁺ excited energy levels as well as the luminescence branching ratios.

Using the methods of spectral ellipsometry and spectrophotometry in the region of intrinsic absorption bands of sol-gel barium titanate films on quartz substrates annealed at temperatures of 450, 600, and 700°C we determined the thicknesses of surface layers, films, and film-substrate transition layers. A decrease in the porosity, thickness, and band gap of the films as well as an increase in their refractive indices and absorption with an increase in the annealing temperature were established. The spectra of refractive indices and absorption are interpolated by the dispersion formulas of new amorphous materials.

In water solutions, spectral-kinetic parameters of quantum dots based on the mixture of semiconductors of I-III-VI groups, namely Ag-In-S, Ag-In-S₂ with ZnS layer (QD AIS/ZnS), show a specific dependence on pH and the local polarity caused by the interaction with polyelectrolytes (spectral shifts, hyperchromism and hypochromism in absorption and photoluminescence spectra, changes of the photoluminescence mean decay). It was argued that changes of QD AIS/ZnS upon variation of the solution pH are caused by the reversible recharging of ampholyte ion groups, which thus alters the structure of the Helmholtz binary layer at the QD surface covered by glutathione molecules. It is shown that the second derivative of QD absorption spectra both in an acid medium and upon interaction with polyelectrolytes corresponds to the Stark linear effect caused by the formation of the QD induced dipole moment. The results obtained and the corresponding conclusions on their basis may be used to develop selective markers for testing local pH and polarity in biomedicine using QD AIS/ZnS.

We calculate and analyze the fields generated by two- and three-dimensional quantum antennas from identical independent two-level emitters. It is shown that two- and three-dimensional quantum antennas permit to achieve much better localization of the distribution of the emitted biphoton and three-photon field and its correlations than one-dimensional antennas. This makes two- and three-dimensional quantum antennas promising for quantum-radar applications.

Using the method of IR-Fourier spectroscopy of attenuated total internal reflection (ATR) we studied the radiation-induced effects in thin films of diazoquinon-novoloc photoresists on the silicon substrate under the irradiation with 5 МeV electrons. It is established that electron irradiation in a dose above 3·10¹⁵ cm^-2 leads to a decrease in the integral absorption in the wave numbers range 3700-400 cm^-1. The intensity of the bands associated with -O-H oscillation and especially aliphatic -C-H bonds decreases the most. At a dose of 1·10¹⁷ cm^-2, the intensity of the bands related to methylene (-CH₂-) and methyl (~CH₃) groups is comparable to the noise level. The intensity of the band ~ 1600 cm^-1, caused by stretching oscillations of the aromatic ring, does not change in the entire dose range 3 • 10¹⁴ cm^-1 • 10¹⁷ cm^-2. The experimental data obtained indicate intense crosslinking of the polymer components ofphotoresists upon electron irradiation. It is found that the radiation-induced changes in ATR spectra depend on the type of photoresist (FP9120, S1813 G2SP15). The experimental regularities of changes in the optical characteristics of thin photoresist films irradiated with electrons are explained with respect to the peculiarities of the radiation chemistry of diazoquinon-novolac resins.

Conventional and chemometric spectrophotometric techniques were compared for their analytical performance in determining a tri-component pharmaceutical mixture containing altizide, potassium canrenoate, and rescinnamine. These components were characterized by a notable spectral overlap, thus making their quantitative determination particularly difficult. The determination of altizide and canrenoate was performed using the technique of different order-derivative spectrophotometry, while rescinnamine was determined by fluorometry with activation and fluorescence maxima respectively at 325 and 427 nm thanks to a total absence of interference from the other two components. The analysis of the mixture was carried out by applying multivariate calibration methods, including principal component (PCR) and partial least squares (PLS) regression approaches. The calibration sample set was defined by a simplex-lattice experimental design to cover the experimental domain distributed over five concentration levels. The prediction accuracy of the defined methods was evaluated through external validation on new unknown samples and commercial pharmaceuticals. Significant advantages were found in the prediction of all the analytes when using the chemometric methods, which proved to be simpler, faster, and showing better statistical results with accuracy values between 96.12 and 103.36% and relative standard errors lower than 1.7%.

The possibility of using chlorophyll fluorescence visualization in practical apple and apricot breeding is considered. A significant influence of water deficit and heat shock on the photosynthetic activity of leaves, estimated from their fluorescent images, is found. It is confirmed that the most sensitive indicator for detecting the degree of drought-induced depression of fruit plants is the effective quantum yield of photosystem II.

We demonstrate a biophysical approach for estimation of the dynamics of a labile pool of zinc ions in human erythrocytes in the range from 1 to 1000 nM using a FluoZin-3 fluorescent probe. This method can be used in biomedical research and become the basis for developing methods for diagnosing or predicting the disease course associated with failure in zinc metabolism.

For use as a standard sample, hypericin was isolated from the “Diahyperon” tincture. The chromatographic purity of the hypericin sample was confirmed by high-performance liquid chromatography/mass spectrometry. Hypericin is represented by a single chromatographic peak with a retention time of 23.10 min, which has a characteristic signal of the molecular ion [M - H⁺] ^- with m/z 504.05 in the mass spectrum. In addition to the band characteristic of hypericin at 550 and 590 nm, the electronic absorption spectra of the “Diahyperon” tincture and a methanolic extract of Hyperici herba (Hypericum perforatum) show an absorption band at 665 nm due to the presence of chlorophyll. It was shown that upon excitation of hypericin (λ_ex = 470 nm), the emission spectrum of the “Diahyperon” tincture contains bands characteristic of hypericin at 593 and 640 nm. In addition to the hypericin emission bands, the emission spectrum of the methanolic extract of Hyperici herba demonstartes a low intensity chlorophyll emission band at 670 nm. It was found that the spectrophotometric and spectrofluorimetric determination of hypericin in “Diahyperon” tincture and in Hyperici herba gives convergent results, which are consistent with the standardized values of the hypericin content in the studied samples.

The lateral resolution is one of the most important hallmarks for evaluating the imaging performance of a confocal Raman microscope (CRM). A method based on the resolution test chart for testing the lateral resolution of the CRM was proposed. The test imaging target comprised a polished silicon substrate coated with a thin metallic pattern, which provided a high contrast and negligible edge effects. By using a singlebar target instead of a conventional three-bar target, quantitative measurements of the lateral resolution of the CRM were possible. Single-bar targets with different widths were used to test a CRM with a nominal lateral resolution of approximately 1 μm. The response of the C'RM to the single-bar target was studied further with a theoretical model, and the relationship between the Michelson contrast of the response function and the lateral resolution was investigated. Finally, the method used to calculate the lateral resolution was described and tested and shown to have a relative repeatability of only 5.6%, which is ideal for resolution testing. Overall, our experimental results showed excellent agreement with simulation results and proved that the single-bar target method was capable of measuring the lateral resolution of CRMs with high accuracy, efficiency and reproducibility.

The features of formation of the range-energy profile of the visibility zone of active-pulse vision systems (AIS) at delay distances comparable to the length of the visibility zone are studied numerically and experimentally. The case of illumination pulse durations shorter than registration durations is considered. During calculations, the shape of the illumination pulse was set either close to the real one or rectangular, and the time sensitivity profile of the photodetector was chosen rectangular. The calculation results for the real pulse profile are compared with the data for the rectangular profile. Numerical studies for a real pulse show that, in contrast to the case of a rectangular pulse, the position of the maximum on the signal-distance dependence does not coincide with the delay distance. This difference decreases when the ratio of the delay distance to the spatial length of the illumination pulse increases. The results of calculations are in good agreement with the measured dependence of the recorded signal value on the distance.

A new approach to the development of an optoelectronic device for molecular orientation of functional materials is proposed. The results of the development of its main components - a collimator of led radiation and a broadband polarizer with a large angular aperture are presented. The problem of collimation of strongly divergent led radiation is considered. It is shown that the use of a modified conical lens is promising for the problem solution. The broadband polarizer with a large angular aperture, which is an important element of the optical-electronic device, has been designed and manufactured on the basis of a mutli-layered structure.

The interrelation between colorimetric (correlated color temperature) and spectral (intensity ratios of spectral emission bands) parameters of the white LED lamps for general lighting has been established based on the analysis of the test results of a set of lamps during aging. Using deconvolution of the lamp radiation spectra, it is shown that the change in color temperature is mainly due to a change in the intensity ratio of the 450 nm band origination from the diode heterostructure and the long-wavelength component of the non-elementary yellow band of the phosphor radiation with a maximum of 580 nm, while the shorter-wavelength component with a maximum of 530 nm manifests itself mainly in changing the total luminous flux. A possible cause of the change in the intensity of the spectral components of the non-elementary radiation band of the phosphor may be both thermal effects and structural changes in the phosphor material.

It is shown that as low temperature narrows the population of “hot” active in antistokes transition molecules, it results in narrowing of range, where by this method the pure electronic transition is localized. As the result, the sensibility to chromophore inhomogeneity is growing. The examples of the pure electronic transition frequency determination from experimental absorption and emission spectra at low temperature are presented.

The photovoltaic and photoconductive properties of film composites of styrene copolymere with nonylmethacrylate. poly-N-epoxypropylcarbazole doped with lanthanide complexes of the composition Ln₂L₆ • PS (Ln = Nd. Eu. Gd. Yb; HL is a ligand of the carbacylamidephosphate type. CCl₃C(O)N(H)P(O)(NEt₂)₂. N- [bis (diethylamino) phosphoryl] -2.2.2-trichloroacetamide; PS = 3.6-dipyridin-2-yl-1.2.4.5-tetrazine. C₅H₄N-C₂N₄-C₅H₄N) have been studied. It is found that in the visible range of the spectrum these composites have a hole type of photoconductivity. and the internal photoelectric effect is determined by the photogeneration of charge carriers from the molecules of the metal complex and the sensitizer. The kinetics of the formation and relaxation of photogenerated charge carriers has been studied by the EPR method. It is concluded that the molecules of the metal complex in the composition of the polymer composite enhance the efficiency of photogeneration of non-equilibrium charge carriers and thereby affect the photovoltaic properties of the composites.

Complete and consistent atomic data, including energy levels, wavelengths, lifetimes and E1, E2, M1, and M2 transition rates, are reported for the low-lying 41 levels of Ga XVII, belonging to the n=3 states (1s²2s²2p⁶)3s²3p³, 3s3p⁴, and 3s²3p²3d. High-accuracy calculations act as benchmarks for accurate treatments of relativity, electronic correlation, and quantum electrodynamic (QED) effects in multi-valenceelectron systems. The calculated energy levels are in excellent agreement with the experimental results and the experimentally compiled energy values of the National Institute for Standards and Technology wherever available. The calculated values, including core-valence correction, are found to be in good agreement with other theoretical and experimental values.

High-accuracy calculations of energy levels, wavelengths, probabilities, and oscillator strengths of transition of resonance lines for Ge-like Pd, Ag, and Cd ions have been performed. For the accurate treatment of relativity, the contributions of Breit interactions and quantum electrodynamics correction were considered. The calculated values of energy levels and wavelengths, including core-valence corrections, are found to be in excellent agreement with other theoretical and experimental values for Ge-like Pd, Ag, and Cd ions. The number of energy levels and wavelengths we considered is larger than that of any other theoretical calculations. The transition probabilities are also given where no other theoretical results and experimental values are available.

The determination of the first and second derivatives in the UV spectra of crude oil and asphaltene solutions allows the identification of signals attributed to compounds in the crude oil that cannot be seen in the normal spectrum. This processing of the crude oil UV-Vis spectrum to determine first and second derivatives allowed the identification of five maxima. The maxima observed in the first derivative spectrum can be related to different types of compounds in crude oil: ~230 nm for benzene compounds, 259 nm for naphthalene compounds and their derivatives, 295 nm for pure phenanthrene, 328 nm for aromatic chromophores with three or four aromatic rings, and 401 nm for the Soret electronic absorption band of vanadyl porphyrins. The shape of the spectra was analyzed to predict the presence of colloids or particles in the solutions.

Two types of adsorbents, zinc oxide (ZnO) and zeolite, have been used to probe the lowest detectable limit of lead (Pb) dissolved in water. To achieve the goal, water-soluble Pb complexes were produced by dissolving in water or titrating with HNO₃ acid with different concentrations of four different compounds of Pb. The dissolved Pb complexes were then allowed to be adsorbed onto ZnO or zeolite. LIBS spectra of the Pb-ZnO and Pb-zeolite composites were recorded in the 331.5-370.5, and 355-394 nm spectral windows, respectively. Calibration curves were drawn using the normalized line intensities of Pb I at wavelengths of 357.269, 363.958, and 368.319 nm versus the concentration of the added Pb. For all the adsorbates (the Pb compounds) used, the adsorption curves as a function of the adsorbate concentration in water followed the Langmuir type isotherms. The lowest limit of detection (LoD) and the slope of the linear part of the adsorption isotherm varied for various adsorbents, adsorbates, and different Pb I emission lines used. ZnO was found to be a better adsorbent than zeolite in terms of LoD and the slope of the linear part of the isotherm and hence the sensitivity of the detection. The LoD for Pb in an aqueous solution in the current LIBS experiment coupled with the adsorption technique was found to be 0.5 ppm.

Simple, sensitive, precise, and validated spectrophotometric methods have been developed for the assay of Mirabegron in bulk and pharmaceutical dosage forms. The techniques are premised on the oxidation of Mirabegron with slight excess of N-bromosuccinimide (NBS), and estimating the unconsumed oxidant by assessing the amount of unreacted NBS by amaranth dye (method A), safranin dye (method B), aniline blue (method C), and rhodamine B (method D) at λ_max = 530, 530, 610, and 560 nm, respectively. Under optimum conditions, Beer's law was obeyed in the concentration range of 5-30, 10-60, 20-45, and 1-15 pg/mL for methods A, B, C, and D, respectively. The proposed methods were validated in terms of specificity, linearity, range, precision, and accuracy. Furthermore, the limit of detection (LOD) and limit of quantification (LOQ) values were also calculated. The recommended methods were successfully applied to the determination of drug in pure as well as in dosage forms, without any interference from the common excipients present in pharmaceutical formulations.

The aim of this study is to investigate the spectroscopic characteristics of phenylalanine in the NIR spectral range as a preliminary step towards the development of an in vivo method for the determination of phenylalanine in the blood of newborn babies. The first steps in this study included in vitro experiments with mixtures of phenylalanine, saline, and whole blood. Results showed absorption bands in the NIR spectral range that are assigned to overtones of C-H, N-H, and O-H in the range of 1400 to 1700 nm, which together with the melanin absorption lines in the visible spectra range, demonstrate the potential of NIR/VIS spectroscopy as an inexpensive, non-invasive, rapid, and accurate alternative to routine methods for determining of phenylketonuria.

In energy dispersive X-ray fluorescence (EDXRF) analytical studies of samples, the absorption and enhancement of analyte X-rays, collectively called matrix effects, complicate the relation between intensity of analyte X-rays and its concentration. Earlier, the absorption and enhancement relative terms have been derived from the built-up experimental relations of analyte X-ray counts with XRF fundamental parameters and the parameters of the experimental set-up for each selective and enhanced X-rays. Now, the terms are implemented on the determined amounts of potassium and calcium nutrients in plants and pot soils from an experiment performed in the lab by growing fenugreek plants on the soils with variable contamination levels and applied fertilizers. The variation pattern of the terms with respective nutrient contents is found to be affected by the basic nature of soils. The pattern shows the high sensitivity of the terms to the plant's behaviour in soil and reflects the picture of supressed benefits of applied fertilizers to the heavy-metals contaminated soils.

We established prediction models based on the combination of spectral and different advanced image features to improve the prediction accuracy of solid-soluble content (SSC) of apple. Eight optimal wavelengths were selected using a new variable selection method called variable combination population analysis (VCPA). Image textural features of the first three principal component score images were obtained using a gray level co-occurrence matrix (GLCM) and a local binary pattern (LBP). Next, a random frog algorithm was developed to select optimal textural features for further analysis. A support vector regression (SVR) model based on spectral and different textural features was developed to predict the SSC of the apple. The model based on eight optimal wavelengths and nine optimal GLCM features of principal component images yielded the best result with the determination coefficient for prediction (R_p²) of 0.9193, root mean square error for prediction (RMSEP) of 0.2955, and the ratio of the standard deviation of the prediction set to the root mean square error of prediction (RPD) with a value of 3.50. These results revealed that the spectral combined with optimal GLCM features from principal component images coupled with the SVR model has the potential for prediction of the SSC of apple.

The effect of integration time on Raman spectral data collected from fresh milk products was investigated and analyzed. The collected spectral data were denoised by wavelet transform to remove signal interference. Two-dimensional correlation Raman spectra of the fresh milk products were then constructed using two-dimensional correlation analysis and laser integrating time as an external perturbation. Finally, feature extraction was carried out, and the Euclidean distance was calculated. Thus, the similarities between fresh milk products of the same brand and different brands were quantitatively analyzed and calculated from Raman spectroscopy, two-dimensional correlation Raman spectroscopy, and feature extraction. The results showed that the quality of fresh milk products of the same brand fluctuated but maintained a high consistency. The differences between different brands of fresh milk products under the same detection conditions were much greater than within the same brand samples.

An effective and fast vortex-assisted dispersive liquid-liquid extraction method was developed for the extraction of paraben in cosmetic samples and water samples. The paraben was determined and quantified using ultraviolet-visible (UV-Vis) spectrometry. A response surface methodology (RSM) based on the central composite design was used for the optimization of factors (composition of the extractant, volume of extractant, extraction time, centrifugation time, and centrifugation velocity) affecting the extraction efficiency of the procedure. The optimum parameters for vortex-assisted dispersive liquid-liquid extraction (VA-DLLE) are: chloroform used as the extractant solvent, 5 ml volume of extractant, 3 min extraction time, 5 min centrifugation time, and 2400 rpm centrifugation velocity. The limit of detection (LOD) and the limit of quantification (LOQ) for paraben are 0.0476 and 0.1442 42 µg/mL, respectively. Spiked cosmetic samples have the extraction recoveries in the range of 81.2-96.8%, whereas spiked water sample extraction recoveries were in the range of 88.8-100.63%. Each sample was repeated (n = 2), with a relative standard deviation of <5.74% for cosmetic samples and <9.03% for water samples. In conclusion, this extraction method is fast and inexpensive for the extraction of paraben.