The paper provides analysis of parameters of prospective samples of atmospheric optical communication lines, or free space optics (FSO), based on quantum-cascade lasers (QCL) compared to existing commercial systems. The results indicate significant advantages of using QCL in FSO compared to existing systems, largely due to long-wave radiation and the feature of QCL modulation dynamics, which is limited by the picosecond lifetime of current carriers that provides a fundamental possibility of obtaining inherent bandwidth of >100 GHz. Possible applications of FSO based on IR QCL and terahertz QCL are discussed taking into account experimental data and unique properties of QCL radiation. The use of non-traditional methods to eliminate the influence of turbulence and increase the capacity of the information transmission channel is also discussed.

Time dynamics of the working characteristics degradation of longitudinally heated furnaces for spectrometers with electrothermal atomization of the sample in the presence of compounds of tungsten, zirconium and palladium used as chemical modifiers has been studied. Visual changes in the state of the investigated furnaces are discussed and the loss of their carbon material during the experiment is shown. The atomic absorption signals of silver and copper recorded at different stages of degradation for unmodified and modified furnaces are analyzed. An explanation of the reasons for accelerated damage to the pyrographite coating and subsequent destruction of the polycrystalline graphite base for furnaces subjected to modification is suggested.

The vibrational properties of ebastine have been investigated by density functional theory (DFT) calculations and Raman scattering experiments. The DFT calculation was performed with geometry optimization and harmonic vibration using the B3LYP function with the 6-31G(d) basis set. The DFT calculated spectrum of ebastine is in good agreement with Raman scattering experiments. A good linear correlation between calculated and experimental wavenumbers has been obtained in the spectral range of 500-3250 cm^-1. Also, the calculated bond lengths and bond angles of the ebastine molecule are consistent with reported X-ray diffraction results. The deviations of bond lengths and bond angles are smaller than 0.034 Å and 3.1°, respectively. In addition, the experimentally observed vibrational modes have been assigned and the characteristic modes of the three parts benzhydryloxy, piperidine-butanone, and tert-butylphenyl of the ebastine molecule have been discussed, which would be helpful for future degradation and activity studies of ebastine.

We synthesized pure and Pb²⁺ ion doped Li₆Gd(BO₃)₃ phosphors via the solid-state reaction method at 700^oC for 5 h in air. The phase analysis of the synthesized materials was determined using DTA/TGA, XRD, and FTIR. The photoluminescence characteristics of pure and Pb²⁺ doped phosphors were investigated at room temperature using a photoluminescence spectrophotometer. The emission and excitation bands of Pb²⁺ doped Li₆Gd(BO₃)₃ were observed at 313 and 242 nm, respectively. The dependence of the PL intensities on the Pb²⁺ concentration for the Li₆Gd_1-xPb_x(BO₃)₃ (0.005 £ x £ 0.025) phosphors was also studied. The highest emission intensity was obtained from 0.02 mol Pb²⁺ doped Li₆Gd(BO₃)₃.

Photoluminescence spectra of Mn²⁺ ions in ZnS single crystals were obtained in the temperature range 77-623 K at different activator concentrations and wavelengths of the exciting radiation. The spectra were decomposed into individual bands, each of which corresponds to the radiation of manganese centers with a certain type of local symmetry. The results obtained made it possible to estimate the effect of activator concentration and temperature on changes in the number of radiating manganese centers with different types of local symmetry relative to all luminescent Mn²⁺ ions in ZnS single crystals under different excitation wavelengths. The results are explained in terms of the redistribution of the direct optical and resonant mechanisms of energy transfer of the exciting light to Mn²⁺ ions, taking into account losses due to nonradiative interaction with the crystal lattice of ZnS single crystals.

The sensitive quantitative analysis of trace heavy metallic elements (Cd, Mn, Cr, and Cu) in aqueous solutions was achieved successfully through the combination of filter paper enrichment with laser induced breakdown spectroscopy. Filter paper was enriched with 0.4 mL aqueous solutions to form a homogeneous sample layer on the surface of the metallic target. Considering the limits of detection, the values deduced with calibration curves already exhibited the high performance of the proposed method at several hundred or 10 mg/L (Cd 0.165, Mn 0.035, Cr 0.012, and Cu 0.078 mg/L), lower than or comparable to those using other similar methods. The LIBS results agreed reasonably well with those from ICP-MS for real samples. All results showed that our method was suitable and accurate for rapid on-site detection of trace metals in aqueous solutions. This indicates that filter paper enrichment combined with laser induced breakdown spectroscopy is a feasible approach to wastewater quality monitoring.

This paper presents an original design of the single-shot iterative frequency-domain interferometry (IFDI) technology to measure the ultrafast phase. Unlike frequency domain holography (FDH), in which the reference pulse interferes with the phase modulated probe pulse, in IFDI two linearly chirped probe pulses co-propagate and are both phase-modulated by the measured ultrafast phase, and then the phase can be reconstructed with the iterative algorithm. Compared with two types of FDH, the IFDI technology has better accuracy and stability.

It is shown that the state of an ensemble of three-level atoms after absorption of a single photon and subsequent spontaneous decays in the presence of a weak gravitational field loses the phase matching of the emitted photons with the wave vector of the absorbed photon. This is similar to the case of an ensemble of two-level atoms. However, when averaging over the state of one of the emitted photons, the spatial distribution of the second photon coincides with the result for a space without a gravitational field.

Radiation-induced processes taking place at boron and phosphorus ions implantation in the positive FN9120 diazoquinon-novoloc photoresist films on silicon were studied by the method of IR- Fourier spectroscopy of frustrated total internal reflection. It was established, that strengthening of photoresist adhesion to monocrystalline silicon is caused by the formation of ester linkages between hydroxyl groups on the surface of oxide layer of silicon wafer and carboxylic groups of 1H-inden-3-carbohylic acid.

The resonance absorption of radio waves (with a frequency of 10 MHz) by c-band electrons in indium antimonide crystals doped with hydrogen-like donors (tellurium atoms) at room temperature in an external magnetic field has been theoretically studied. The known experimental data obtained for samples with electron concentrations in the range from 6 · 10¹⁵ to 5 · 10¹⁸ cm^-3 are analyzed and interpreted. Our calculations based on the laws of conservation of energy and the quasi-wave vector for electrons and optical phonons have shown that the resonance absorption of radio waves by n-InSb:Te crystals in the magnetic field is due to a spin-phonon resonance. The resonance arises as a result of the spin-flip interaction of the c-band electron with the optical phonon, assisted by the resonant radio wave absorption in the magnetic field. A physical picture of the phenomenon is given, analytical relations are presented, and calculations are carried out that are consistent with the experimental data that previously could not be interpreted at all.

A preparation procedure is proposed and stabilized suspensions of aluminium nanoparticles with a wide size distribution in isopropanol are obtained, their morphological, physicochemical, and optical characteristics are studied. The spectral dependences of the extinction cross-section of nanoparticle suspensions were calculated according to the Mie theory and compared with experimental data. The growth of the natural oxide shell of nanoparticles was studied.

The spectral-luminescent properties of molecules of 2,3,9,10,16,17,23,24-octacarboxyphthalocyanine and its zinc complex embedded in nanoporous silicate gel matrices were studied. It was found that at the initial stage of the silicate framework formation, H-aggregates of the studied phthalocyanines are formed. The effect of the monomeric form recovery of the zinc complex in the gel matrix during the drying of silicate material was discovered. The reasons for the destruction of aggregates in a limited volume of nanoscale matrix pores are discussed.

A system for detection of ethylene (C₂H₄) at high pressure is developed based on tunable diode laser absorption spectroscopy using a distributed feedback laser near 1620 nm. To eliminate the influence of spectral line overlap under high pressure, a differential absorption (peak minus valley) scheme is adopted. The peak and valley wavelengths used for the measurement correspond to 6174.64 and 6174.45 cm^-1, respectively. Absorption cross sections of ethylene are measured for the selected peak and valley wavelength. The measured concentration agrees with the known concentration, and the maximum of the standard deviation is 0.746% for all measurements. In addition, long-term continuous measurements indicated good stability of the system. The sensitivity of the system is ~18 ppm with an optimum averaging time of 110 s. All the experimental results validate the applicability of the system in ethylene trace detection.

In order to establish a catalyst formation for refininging Ashalcha heavy oil, the active form of the iron-containing catalyst, mixed iron (II, III) oxides, was investigated using Mössbauer spectroscopy. During the formation process, the iron oxide phase is involved in the cleavage of carbon-heteroatom bonds and provides a decrease in molecular mass of resins and asphaltene fractions of heavy oil. Thus, dispersed iron oxides are enriched in a sulfur-containing phase. As the duration of the experiment increases, the conversion degree of resins and asphaltenes increases, which indicates the multiple participation of dispersed iron compounds in the cleavage of chemical bonds. The results of Mössbauer spectroscopy indicate the reduction of maghemite to magnetite when iron oxides interact with water vapor during the catalytic aquathermolysis of crude oil at 250 °C.

A method is proposed for the complex analysis of fluctuations in the fluorescence intensity of molecular compounds, which allows determining the structural composition of protein oligomers. The idea of the method is to analyze the photon counting histograms of experimental measurements using principal component analysis to assess the presence of oligomeric compounds, and to perform hierarchical cluster analysis, to determine the data classes corresponding to various molecular compounds, followed by selecting cluster medoids to determine the oligomeric composition of protein complexes. The efficiency of the analysis algorithms developed within the framework of the proposed method was confirmed on simulated and experimental photon counting histograms of the measured fluorescence intensity fluctuations of monomeric and dimeric forms of green fluorescent protein (GFP).

We investigated the influence of drugs (dapsone, paracetamol and isoniazid) on the reactive oxygen and halogen species production by neutrophils. The standard fluorescent method based on scopoletin, as well as the recently developed fluorescent methods based on oxazine dyes, celestine blue B and gallocyanine, were used for this purpose. Celestine blue B selectively reacts with hypochlorous acid, and gallocyanine reacts mainly with the superoxide radical anion, which permits to reveal the regulatory effect of anti-inflammatory drugs on the neutrophil NADPH-oxidase and myeloperoxidase activity, responsible for the reactive oxygen and halogen species production, respectively. The obtained results indicate that gallocyanine and celestine blue B dyes are promising chemosensors to study the effect of drugs used in anti-inflammatory therapy on the neutrophils respiratory burst.

Magnetic nanoparticle-graphene oxide (Fe₃O₄/GO) nanocomposite was synthesized for two reasons: this is a good adsorbent for the adsorption of methylene blue (MB) and methyl orange (MO) from aqueous solutions; and due to its magnetic properties, it can be easily separated from aqueous solution using a magnet. This adsorbent was characterized by FTIR, SEM, and XRD techniques. Several parameters such as pH of the solution, the amount of adsorbent, adsorption time, type and volume of elution solvent, and desorption time were optimized to improve the adsorption recovery. The maximum adsorption recovery was obtained at the optimized solution pH of 6.0 using 10.0 mg adsorbent for 10.0 min. According to the Langmuir isotherm, the maximum adsorption capacity was 666.7 and 714.3 mg/g for MB and MO, respectively. The limit of detection (LOD) was also determined as 0.9 and 1.0 µg/L for MB and MO, respectively. Owing to the good repeatability and reproducibility of this adsorbent, it can be considered as a promising candidate for water treatment purposes. Consequently, this adsorbent was used for the adsorption of MB and MO from natural water samples.

We consider the realization of logical operations for images using the accumulated long-lived echo hologram. It is shown that, depending on the phase difference between the exciting pairs of laser pulses, it is possible to carry out a number of logical operations, namely, combination and symmetric difference of sets as well as their superposition.

We constructed the surface of the normal component of the inverse tensor of the dielectric permittivity of a cubic photorefractive piezoelectric Bi₁₂SiO₂₀ crystal. A volume phase holographic grating with a wave vector along the crystallographic axis was recorded in this crystal. It is established that the combined action of the photoelastic and piezoelectric effects leads to increasing the normal component of the inverse tensor of the dielectric permittivity along the direction and decreasing the normal component of the inverse tensor of the dielectric permittivity in the perpendicular direction. It is revealed that the anisotropy of the contribution of the photoelastic and piezoelectric effects causes an increase in the output energetic characteristics (optimized in the azimuth of polarization of light waves) for the transmission hologram and their decrease for the reflection hologram.

We present the results of the numerical modeling of the Al₂O₃-SiO₂ single layer composite antireflection coating for silicon solar cells, its manufacturing and investigation of the reflection integrated coefficient R_S £10 %. It is shown that when the concentrations of Al₂O₃ , SiO₂ are in the ranges 52-84 % and 16-48 % (weight %), respectively, and the thickness of layers is within the 53-97 nm area, the minimum of Rs is achieved for the Al₂O₃ = 73-77 %, SiO₂ = 27-23 % and 69-75 nm thickness. It is also shown that for layers of Al₂O₃: SiO₂ = 75:25 % with a 72 nm thickness the value of R_S is 3.53 %, which is approximately twice lower than R_S for the Si₃N₄ coating.

We theoretically and experimentally investigated the process of laser photothermoacoustic transformation in sensor semiconductor structures. We obtained the expression for a pressure pulse describing the evolution of an ultrasonic response excited by a nanosecond laser pulse with a Kummer-Gaussian intensity distribution. The possibility of effective control of the process of photothermoacoustic transformation of laser pulses in semiconductor structures used for creating highly sensitive detectors of ionizing radiation was experimentally demonstrated.

Indirect ablation laser induced breakdown spectroscopy (IA-LIBS) was applied to the analysis of the nonmetallic constituents of engine oil and considered as a feasible technique for the evaluation of the consumption and/or combustion of engine oil during routine engine operation. The evolution of CN emission and C₂ emission was investigated for different driving time intervals of the motor. The exponentially decaying curve showed that the intensity of CN emission and C₂ emission decayed at different driving time intervals. The evolution of total CN emission and C₂ emission was analyzed, and the ratio of CN to C₂ was calculated, which might be taken as an indicator to evaluate the performance of the used engine oils and/or to diagnose the conditions of the motor engine. Thus, it is shown that IA-LIBS is a potential method for analyzing the metallic and nonmetallic constituents of engine oil.

Tert-butylphenethylcarbamate (1) and 1,1-dimethyl-3-phenethylurea (2) were synthesized, and their structures were confirmed by NMR, FTIR, and mass spectrometry techniques. The experimental spectroscopic data of 1 and 2 were compared with the corresponding calculated ones obtained by density functional theory (DFT) and time-dependent DFT methods, for which the hybrid functionals B3LYP, B3P86, and PBE0 combined with the 6-311++G(d,p) basis set were tested. The solvent effect was considered using the implicit model - integral equation formalism-polarizable continuum model (IEFPCM). Relatively good correlation (R² > 90%) was obtained between the experimental and predicted spectral data. The conformational effect on the absorption maximum l_max was negligible, that is, l_max of different conformers varied by less than 0.01 nm . Hirshfeld surface analysis and electrostatic potential calculations of the closest intermolecular contacts between active atoms of 1 and 2 revealed that the closest interactions were between hydrogen atoms of 39.6 and 46.3%, respectively.

The pyrolysis of low-rank coal is considered as the optimal method of realizing clean and efficient production of blue coke, tar, and gas. The experiments of low-rank coal microwave pyrolysis under CO₂, CH₄, H₂, and circulating gas (CG) are studied in a custom-designed microwave oven to clearly clarify the effects of reaction atmospheres on pyrolysis temperature, products yields, and spectroscopic characteristics of pyrolysis products by the analysis techniques of FT-IR and GC-MS. The results show that among four pyrolysis atmospheres, the temperature-rise rate and final pyrolysis temperature under H₂ atmosphere are both highest, taking only 5.6 min to arrive at 750°C, and the final temperature is greater than 950°C. The liquid yields under CO₂, CH₄, H₂, and CG atmospheres are 21.8, 24.4, 28.2, and 26.8 wt.%, respectively. The contents of -OH, aromatic ring C=C double bond, and -C=O in the solid product under CH₄ atmosphere are highest, possibly because of the thermal polycondensation and the secondary degassing of the solid product. The hydrogenation of H free radicals dissociated from “rich hydrogen” gas results in an improvement in the alkane content and a decrease in the aromatic hydrocarbon content in tar, which is confirmed by the change in oxygen content in the solid product. The hydrogenation technique of circulating coal gas on low-rank coal microwave pyrolysis is economical, energy-efficient, and feasible, which is helpful in the development of coal processing technologies.

Eu³⁺ doped NaLaMo₂O₈ phosphors were synthesized by a conventional solid state reaction. The phase and luminescent properties of the synthesized phosphors were investigated in the current work. In NaLaMo₂O₈, Eu³⁺ ions replace La³⁺ ions and form solid compound. This substitution induces the 2θ angles of diffraction peaks to shift to larger values. Under excitation at 395 nm, NaLaMo₂O₈:Eu³⁺ phosphors exhibit emission bands in the range of 550-725 nm originating from ⁵D₀®⁷F_J transitions (J = 0, 1, 2, 3, 4) of Eu³⁺ . The strongest emission band corresponds to the ⁵D₀®⁷F₂ transition, which indicates a site of Eu³⁺ without inversion symmetry in NaLaMo₂O₈. The Eu³⁺ concentration has obvious influence on the luminescent properties of NaLaMo₂O₈:Eu³⁺ phosphors. NaLaMo₂O₈:6mol%Eu³⁺ has the strongest excitation and emission intensities.

The purpose of this work is to report an analytical procedure to prove the validity of the hypothesis of the representativeness of the mass vaporized in the plasma plume of the studied sample. To achieve that, we used the laser induced breakdown spectroscopy (LIBS) technique to analyze some minerals and trace elements in cow tail hair. First, hair samples were dissolved in nitric acid; then the solutions were analyzed by atomic absorption spectrometer. Ca, Mg, and Na mass concentrations were determined for the 25 hair samples. Finally, a small amount of hair from every strand was cut in very small pieces and mixed with potassium bromide to make 12 mm diameter pellets. The laser was focused on the pellet surfaces, and the intensities of the emission lines of the studied elements were related to their absolute mass concentrations already measured. Experimental conditions were chosen to guarantee the reproducibility of ablations and to minimize the fluctuations of the ablated mass. In addition, local thermodynamic equilibrium was verified to prove the possibility of use of the theoretical model to obtain the variation of the emission line intensity as a function of the species concentration in the plasma plume.

Using the terahertz time-domain spectroscopy system (THz-TDS), the potassium sorbate content in milk powder has been investigated. Firstly, the THz time-domain spectra of the samples were transformed into frequency spectra by Fourier transform, and then, through a set of simplified formulas of the optical parameters, the THz absorption spectra and refractive index spectra were obtained. Based on the characteristic absorption peak of potassium sorbate, a quantitative analysis model of potassium sorbate in milk powder was constructed using Ordinary Least Squares (OLS) linear regression. In the case of low content (<1%) of potassium sorbate, a special THz absorption band (0.887-1.000 THz) was selected to construct a Partial Least Squares (PLS) model that is called Sub-PLS. In addition, for qualitative analysis, we used partial least squares discrimination analysis (PLS-DA). Experimental results show that the proposed Sub-PLS model is superior to the PLS mode based on full spectrum in accuracy, and the proposed PLS-DA is superior to other nonlinear regression methods such as support vector machine and neural network.