Infrared spectra of alunite group minerals formed on the thermal fields of the Pauzhetsko-Kambalno-Koshelevo region (South Kamchatka) were investigated. Interpretation of the vibrational spectra was carried out using the correlation diagrams for the structure of the minerals. In the transition from [AlO₆] to [FeO₆], the ν₃, bands active in the IR spectrum shift from 600, 630 and 670 cm^–1 to 500, 530, and 630 cm^–1; bands ν₁, which are active in the Raman spectrum, shift from 530 to 470 cm^–1. The bands due to the oscillations [SO₄] are active in both spectra and practically do not change their position at the transition from M^IAl₃(SO₄)₂(OH)₆ to M^IFe₃(SO₄)₂(OH)₆.

The population distribution of the molecules on triplet level in a glassy solution of organic compounds at different intensity of the excitation light and several concentrations has been investigated by computer simulation. The dependence of the triplet level population distribution on these quantities was found. It was shown that the effect of the excitation light intensity on the concentration dependence of the luminescence intensity is a consequence of the found relationship between these quantities, when the change of the population of the ground state of molecules as a result of transition of molecules to the triplet state cannot be neglected.

Measurements of the relative fluorescence intensity and the lifetime of the excited states of the Ce³⁺ ions in an aqueous solution of cerium nitrate at various graphene oxide concentrations have shown that under the optical excitation of Ce³⁺ static quenching of fluorescence by graphene oxide takes place. The Stern-Volmer association constant of aquacomplex cerium with graphene oxide is measured to be 24.7 L/g. This value is much lower than the constants for cationic dyes of rhodamines and metal cations and is explained by the presence of negative charges on the interacting particles.

The NH-tautomerization in the lowest singlet S₁ state of the 5,10-mesityl-15-(2,6-dichloropyrimidinyl)-corrole free base was studied in temperature range 278—318 K. It was shown that the NH-tautomerization was the dominant channel for the deactivation of the electronic excitation energy of the short wavelength T2 tautomer. The NH-tautomerization was found to cause the significant changes in quantum yields of the electronic energy deactivation of this tautomer as a function of temperature. When temperature rises up to 318 K, almost 90% of the electronic excitation energy of the corrole ensemble in the solution accumulates on the singlet S₁ state of the long wavelength T1 tautomer after phototautomerization.

The spectral-kinetic characteristics of the annihilation delayed fluorescence (ADF) of 7-azaindole solution in cyclohexane were measured at room temperature. Two bands with maxima at 345 and 480 nm were observed in the ADF spectrum. The short-wavelength band is interpreted as ADF of dimers formed due to dipole-dipole interactions of molecules in excited singlet and ground states, which are populated as a result of triplet-triplet annihilation of monomers. The long-wavelength band refers to the ADF of dimertautomers, which are formed due to the double hydrogen bond and double proton transfer. Excited singlet states of dimers-tautomers are populated as a result of the mixed annihilation of the triplet states of monomers and dimers-tautomers. The decay kinetics of triplet states of monomers and dimers-tautomers is determined mainly by triplet-triplet annihilation processes.

The method of Raman spectroscopy has been used to obtain in situ information on the structure of high-temperature ion melts of YbCl₃-MCl (M = K, Cs). The force constant of the Yb–Cl bond and the orientational relaxation time of the YbCl₆^3– complex ionic group are calculated. Empirical equations describing the correlation between the dynamic characteristics of the YbCl₆^3– complex and the conductivity of the studied melts are obtained.

An algorithm is proposed for mathematical processing of Mössbauer spectra of solid solutions by the Tikhonov regularization method using the Voigt function as an elementary line. For the cases of the spectra processing of Fe_100–xGe_x solid solutions (x = 5—25 at.%) and Fe₇₅Si₁₅Al₁₀, we demonstrate that the algorithm permits to obtain a physically grounded solution, significantly improves the quality of spectra processing, and expands the possibilities of the Mössbauer spectroscopy method. It is shown that the Voigt function is a satisfactory approximation for taking into account the statistical ensemble of nonequivalent local atomic configurations of Fe atoms in disordered solid solutions.

The ZnS:Mn²⁺ nanowires (NWs)/SiO₂ nanocomposites and Au nanoparticles (NPs) were used for the first time as donors and acceptors to detect DNA hybridization basing on the mechanism of fluorescence resonance energy transfer (FRET). The ZnS:Mn²⁺ NWs/SiO₂ core/shell nanocomposites with the average diameter of 25 nm were synthesized by the Stöber method. The Au NPs with the average diameter of 19 nm were prepared by the seed-mediated growth method. The fluorescence intensity of ZnS:Mn²⁺ NWs/SiO₂-dsDNA-Au NPs conjugates decreased extremely compared with that of ZnS:Mn²⁺ NWs/SiO₂-DNA conjugates, indicating that FRET occurred between the ZnS:Mn²⁺ NWs/SiO₂ nanocomposites and Au NPs. When the target DNA sequence was added, the fluorescence intensity was restored. Thus, the selective hybridization of the probe DNA to the target DNA can be used for detecting the target DNA.

Ethamsylate was determined in the presence of its known degradation product, hydroquinone, as an impurity using spectrophotometric methods. Four spectrophotometric methods; second derivative, derivative ratio, ratio difference, and dual wavelength, were evaluated. The accuracy, precision, and linear range were determined for each method, and the methods were validated as per ICH guidelines. The specificity of each method was assessed by analyzing synthetic mixtures containing different proportions of the degradation product and drug. The developed methods were applied to the determination of ethamsylate in bulk powder and two dosage forms.

The different methods (correlation, logistic regression, median and random forest methods) for the selection of informative characteristics of the intensity distribution of fluorescent nuclei on multichannel luminescent images of cancer cells are considered. The input data are the three-channel RGB images. In total, 39 standard characteristics of distributions are studied, including 13 characteristics per each color channel. It is established that the use of 6 features permits to achieve the same classification accuracy as for using 39 features. Moreover, one can use only two features with an insignificant increase in the classification accuracy (by 0.005). It is proposed to use the data of the immunohistochemical analysis of biomarkers in breast cancer cells during the analysis of luminescent images when processing the results in oncocytology.

A method for monitoring dynamic wound changes in video sequence based on integral optical flow is proposed. The method first analyses frame by frame sequentially and then builds integral optical flow and motion maps for video sequence. Motion maps allow to determine the rate of epithelialization of wounds in critical regions that are characterized by violation of tissue growth. From motion maps, we also determine stages of tissue healing. Dynamic characteristics of wound tissue changing are introduced and calculated.

The dynamic range of charge-coupled devices (CCD), such as TCD1304АР, detector for atomic emission spectrometers is studied. For this purpose, we used the authors’ novel equipment with original methods for measuring the temperature of sensors and analyzing nonlinear distortions at different signal levels. To control the nonlinearity of the paths of accumulation and charge transfer, we used the principle of reciprocity of the brightness of spectral lines and exposure. Measurement data processing and compensation of nonlinear distortions at different signal levels were carried out by the maximum likelihood method. The conditions were revealed under which distortions occurred not only at large but also at small signals. A method of using the blooming effect to expand the dynamic range of CCD detectors is proposed.

The problem of determining the total column (TC) of R-12 freon (CCl₂F₂) from IR solar spectra is considered. The spectra were measured by the Bruker FS125HR Fourier interferometer at the NDACC St. Petersburg station. A set of optimal parameters of the inverse problem solution was obtained. The R-12 TC was retrieved above the station in 2009–2018. Estimation of the systematic and random errors were 2.7% and 2.5%, respectively. Preliminary trend estimate was –0.46 ± 0.06% per year.

To promote the use of imaging spectroscopy to assess the nutritional status of apple trees, the models to estimate the chlorophyll content of apple leaves were explored. Spectral data for apple leaves were collected with an imaging spectrometer and then preprocessed with the nine-point moving weighted average method. Correlation analyses were conducted between chlorophyll content and mathematically transformed spectral data. Wavelengths sensitive to chlorophyll content were selected on the basis of the highest correlation coefficients, and partial least squares (PLS), support vector machine (SVM), and random forest (RF) models to estimate chlorophyll content were established and tested. The wavelengths sensitive to chlorophyll content were 414, 424, 429, 439, and 577 nm. The best model was the SVM model with wavelength data subjected to a second order differential of the logarithm transformation (lgR₄₁₄)², (lgR₄₂₄)², (lgR₄₂₉)², (lgR₄₃₉)², (lgR₅₇₇)² as the independent variables. For this model, the coefficient of determination V-R² was 0.7372, the root mean square error V-RMSE was 0.4477, and the residual predictive deviation V-RPD was 1.8810. Among all the models, this SVM model had the highest V-R² and V-RPD values and the lowest V-RMSE value.

А quantitative analysis method to determine the total nitrogen content in monoammonium phosphate (MAP) fertilizer using visible-near infrared (Vis-NIR) spectroscopy and least squares support vector machine (LS-SVM) is proposed. Sample set partitioning based on the joint x-y distance (SPXY) was used to select the calibration set. Fourteen spectral pre-processing methods were then employed to deal with the spectral data including Savitzky-Golay (SG) smoothing, first derivative (D¹) and second derivative (D²) with SG smoothing, multiplicative scatter correction (MSC), standard normal variate (SNV), wavelet, and combination thereof. Next, the LS-SVM model with radial basis function kernel was established with the best pre-processing method, and its performance was compared with that of partial least squares (PLS) model. The results revealed LS-SVM calibration with the discrete wavelet transform provided the best prediction for total nitrogen content in MAP fertilizer, yielding R², root mean square error of prediction (RMSEP), and ratio of performance to deviation (RPD) values of 0.91, 0.101, and 3.34, respectively.

We suggest a method for calculating the optical properties of composites known as a transparent matrix with residual porosity and metal nanoparticles based on the solution of the transport equation of monochromatic radiation using the spherical harmonics approach under the Fresnel boundary conditions. For the method approbation we carry out the modeling of monochromatic radiation transfer in the cyclotrimethylenetrinitramine–aluminum nanoparticles composite with Rayleigh distribution of the pore radii for the cases of four practically important wavelengths. It is shown that in the case of small pores the reflectance increases when the mass fraction of nanoparticles increases too. In the case of large pores, the transmittance dependence on the nanoparticles’ fraction shows a kink for the point relative to the pores totally filled with metal. The possible applications of the results for spectroscopy inverse problems are discussed.

A novel extraction and purification method for identifying pure materials in space targets is presented in this paper. Simulation experiments are carried out using data from the United States Geological Survey and laboratory sample material. Experimental results show that the proposed method can successfully improve the unmixing of sparse spectra. This algorithm should also be suitable for other spectral analysis applications.

We study the effect of Be atoms in the corundum structure by using UV-Vis-NIR spectroscopy as well as X-ray absorption spectroscopy on synthetic ruby samples obtained by the Verneuil process. From the X-ray absorption near edge structure (XANES) spectra, the Be atoms are shown not to be related to the Cr environment. Furthermore, the UV-Vis-NIR absorption spectra are similar for the unheated, traditionally heated, and Be-heated synthetic ruby samples. However, the Be atoms are able to produce a brown-colored center, and the mixing of the red and the brown colors yields the orange in the Be-heated synthetic ruby samples. We propose that the orange color in the Be-heated synthetic ruby samples is caused by the Be²⁺ donor state at 475 nm (2.61 eV) in multiple UV-Vis-NIR wavelength excitation spectra.

The photoconductive and photovoltaic properties of film composites based on poly-N-epoxypropylcarbazole doped with the metal complex – a derivative of nickel dithiolene are studied. It has been found that these composites possess a hole type of photoconductivity and the internal photoeffect is determined by the photogeneration of charge carriers from the metal complex and the transport of holes through the donor fragments of the polymer matrix.

The implementation of logical operations on signals using stimulated echo-holography in the case when it is excited using an object laser pulse carrying information and a pulse acting as a frequency filter is considered. It is shown that the stimulated echo-hologram can be used to implement the conjunction operation.

It is shown that the method for determining the frequencies of purely electronic transitions from diffuse electronic absorption or emission spectra of molecules based on the adiabatic approximation and thermal equilibrium in the initial state of transition can be applied to color centers and F-centers of crystals and glasses. Based on experimental data it is shown that the method can be used, in particular, to monitor the homogeneity of chromophores and possibly containing them media.

Dy³⁺ doped NaSr₄(BO₃)₃ phosphors were prepared using the combustion method.The prepared phosphors were characterized by X-Ray powder diffraction analysis. The excitation and emission spectra of the synthesized phosphors were analyzed with a fluorescence spectrometry. It is established that the NaSr₄(BO₃)₃:Dy³⁺ phosphor emits blue (482 nm), yellow (575 nm), and red (666 nm) light under ultraviolet excitation of 352 nm. Finally, the photoluminescence properties of the synthesized phosphors with different Dy³⁺ doping concentrations were analyzed. The optimum concentration of the Dy³⁺ ion in NaSr₄(BO₃)₃ was found to be 0.0025 mole.

Two new luminescence systems were revealed in natural diamond crystals with signs of plastic deformation. The systems appear under 785 nm laser excitation at 77 K. The first system consists of a set of doublets 0.0162 eV, the distance between them is 0.0435 eV, the position of the head line is 1.392 eV. The second system includes lines 1.309, 1.288, 1.256, 1.214 eV. The intensity of the systems reaches 50% of the Raman scattering line.

The thermal emission spectra of the Al₂O₃/Er₃Al₅O₁₂ (EAG) eutectics used in thermophotovoltaics are interpreted by decomposing on the emission spectra of Al₂O₃ and Er₂O₃ oxides. The part of selective emission of Er³⁺ ions at EAG temperature of 1500 K is about 0.2 and is maximal in the Er₂O₃ coating.

Two μ₃-oxo carboxylate-bridged heteronuclear complexes, [Fe₂^IIINi^IIO(O₂CC₂H₅)₆(H₂O)₃]·H₂O and [Fe₂^IIINi^IIO(O₂CC₂H₅)₆(py)₃] ·py, were prepared and characterized by several spectroscopic techniques including NMR, X-ray diffraction, IR, ESR, and UV. X-ray diffraction measurements demonstrated that the Fe₂NiO clusters of the complexes were close to threefold symmetry in crystals. The ligands coordinated to different metal atoms were almost equivalent in the IR timescale but in equivalent in the NMR timescale. The NMR results showed that the largest ¹H NMR chemical shift of the complex was 95.1 ppm, implying its paramagnetic property, which was weakened by the antiferromagnetic interaction of metal ions through the μ₃-O bridge. NMR and IR studies indicated that the complexes were stable in various nonpolar and moderately polar solvents, such as CDCl₃ and d₃-MeCN, but they were decomposed into metal ions and the corresponding ligands in strong polar solvents, such as water, at room temperature. Assignments of the ¹H NMR spectra of the complexes were made on the basis of relative intensities, broadening, variable temperature experiments, spin-lattice relaxation times, and substitution by appropriate ligands. The ¹H spin-lattice relaxation time T₁ and variable-temperature NMR experiments were also applied to investigate the solution structures and dynamics of the complexes. It is worth noting that the ¹H chemical shift of the pyridine coordinated to the metals could be greater than 90 ppm

The present study aimed to propose a new method for the optimization of neural networks, known as self-constructing neural network (SCNN), to discriminate the Raman spectra of normal tissues, as well as primary and metastatic (secondary) cancers. According to the results, this novel method could significantly improve the ability of the neural network and thoroughly classify the Raman spectra relating to the pathologic states (100% accuracy).

A Mie-Rayleigh-Raman lidar system was used to invert the optical properties of aerosol and determine the lidar ratio. Subsequently, the real-time lidar ratio was used to modify the Fernald method; 1167 groups of data were used to invert the aerosol lidar ratios. We determined the average aerosol lidar ratio profile, which ranged from 30 to 45 in Nanjing, China. Because the Raman signal had a low SNR (Signal Noise Ratio) and the Raman channel was only available at night, it was not possible to make the correction using a real-time lidar ratio. Therefore, an average lidar ratio was used for the correction. The hypothetical value of the lidar ratio used in the Fernald method deviates from the actual value, which can result in errors. Furthermore, large errors can be produced when clouds are present on the lidar line. The accuracy of inversion of the aerosol optical characteristics can be significantly improved by correcting the Fernald method using the real-time lidar ratio or average lidar ratio.

This paper presents a handheld micro-fluorescence spectrometer with an integrated ultraviolet light-emitting diode. A small transmission grating was used as a dispersive element to disperse light. The spectrum was detected by a CCD array. The instrument can be connected to a PC or a smartphone through a USB cable for data processing and spectrum display. The spectrometer is 30×30×100 mm³ only. The spectrometer with a wavelength range from 380 to 750 nm had a spectral resolution of 3 nm. The fluorescence spectra from edible oil, chlorophyll, and paper were measured by the spectrometer we designed. This spectrometer has the advantages of compact structure, small size, light weight, fast detection speed, convenient use, and low cost.

UV-visible spectrophotometry with Arsenazo III is used to determine the samarium concentration. The results confirm that the concentration of Sm³⁺ in the aqueous solution from 2.7×10^{- 6} to 10.8×10^{- 6} mol/L obeys the Lambert-Beer law. The quantitative relationship between the absorbance and concentrations of Ca²⁺ and F^- in the solution with 2.7×10^{- 6} mol/L Sm³⁺ has been obtained. The absorbance of the solution with 10.8×10^{- 6} mol/L Sm³⁺ is found to be 0.58, which is not affected by the concentrations of Ca²⁺ and F^-. So, if the concentration of Ca²⁺ and F^- were known, the quantitative relationship between absorbance and Sm³⁺ concentration can be obtained, which is convenient for determining the Sm³⁺ concentration in aqueous solution with Ca²⁺ and F^- by UV-visible spectrophotometry.

We demonstrate in this paper the shape-controlled synthesis of CuInS₂ micro-/nanoparticles through a facile hydrothermal method. Samples with different morphologies, i.e., nanoparticles and porous microspheres, are hydrothermally prepared in the presence of Gemini surfactant 1,10-bis(4-methyl-4-hexadecylpiperazine)decamethylene dibromide (Pi-16-10-16) as soft template. The products were characterized by using SEM, XRD, XPS, and EDS. Furthermore, the charge-discharge capability of the as-prepared CuInS₂ samples is investigated by using the samples as the cathode in a lithium battery. The charge-discharge curves for the cells of CuInS₂ exhibit higher initial discharge capacity showing a discharge capacity of 673 mAh/g,which is important for potential applications in photovoltaic (PV) and photoelectrochemical areas.

Two exchangeable LSPR modes with different coupling field are observed in calculating magnetic field intensity in accordance with adjusting geometrical parameters. Compared with planar nanostructures, three-dimensional windmills show stronger optical activity, and the maximum value of the asymmetry g-factor was 0.6. The numerical simulation results in this paper also contain the optimal geometrical parameters to achieve the best circular dichroism effect at different resonance modes. The results give a contribution to the design of novel chiral optical nanostructures.