In pure CO₂ and CO₂:O₂=1:2 and CO₂:N₂=1:2 gas mixtures, unsaturated absorption coefficients are measured, using a tunable CO₂ laser, at the central frequencies of the R(8), R(22), P(8), P(22) and P(36) СО₂ 10⁰0-00⁰1 transition lines under a pressure of 100 Torr in the 300-700 K temperature range. The collisional broadening coefficients of the CO₂ spectral lines for O₂ and N₂ molecules are obtained. The temperature dependencies of these coefficients are approximated by power functions with two different indices.

The Raman spectra of polyvinyl alcohol-potassium thiocyanate polymer films are studied. The parameters of the vibrational and orientational relaxation of thiocyanate ion in the polymer matrix are determined. At salt concentrations c > 0.3, the character and velocity of the vibrational dephasing and orientational relaxation become identical to the vibrations of SCN ion in the aqueous solution.

The dependences of single-crystal YAG:0.5 %Er³⁺ spectra in the range 200-1700 nm and the kinetics of the integrated emission on the excitation energy density W of a single CO₂ laser pulse of ~100 ns FWHM duration at l_ex = 10.6 µm were experimentally investigated. The spectra qualitatively changed when W exceeded the threshold of emergence of the laser plasma W_t near the surface of monocrystals. At W < W_t, the spectra of YAG:0.5% Er³⁺ were represented by peaks of the selective emission (SE) of Er³⁺ multiplets on the pedestal of the continuous spectrum. New emission peaks and an additional pedestal corresponding to the emission spectra in a laser-induced air plasma with intensities much higher than the SE peaks appeared due to the air ionization near the crystal surface at W > W_t. The shape of the oscillograms of the integral emission in the range 600-1700 nm was characterized by a front duration of pulses τ_f = 1.0-1.6 µs and a decay time of 2.5 µs when W changes by one order. The kinetics of the integrated emission intensity was explained by calculations of the single-crystal temperature and the population of Er³⁺ energy levels in the conversion of thermal energy into the SE during unsteady energy transfer by internal radiation and thermal conductivity.

This paper presents a system of relationships describing the powers of the Stokes components, generated separately or simultaneously by a steady-state Raman laser. Using the generation of one, two, and three components as examples, it is shown that with the obtained relationships the operation of a laser system can be relatively simply optimized.

The proposed model of an effective medium, in which the Maxwell-Garnett matrix medium is filled with the Bruggeman medium, is used in solving inverse problems of multi-angle ellipsometry to determine the composition of the transition layers surrounding the layer of thermal silicon dioxide on a silicon substrate. The volume factors of filling the layer correctly reflect possible structural transformations during the oxidation of crystalline silicon.

The structure and photochromic transformations of composite organometallic nanostructured systems consisting of Ag nanoparticles with a shell of photochromic diarylethene (DAE) molecules, obtained by deposition from various solutions to nanoparticles, were studied using vibrational spectroscopy methods (infrared (IR) absorption and surface enhanced Raman scattering (SERS)) and quantum chemistry. An analysis of the experimental data showed that the studied nanostructured systems exhibit photochromic properties manifested in the reversible photoinduced change of the relative intensities of the SERS bands related to the vibrations of the bonds participating in the reversible photoisomerization reaction. The spectral manifestations of the chemical interaction between metal nanoparticles and DAE molecules were detected.

Powders of boron-doped and phosphorous-doped detonation nanodiamond and sintered pellets made of non-doped nanodiamond powders were studied by the electron magnetic resonance and X-ray diffraction methods. The possibility of doping of the detonation nanodiamond crystal by boron and phosphorous was demonstrated. The possibility to use these methods for diagnostics of the doped diamond nanocrystals during shock-wave synthesis has been established.

The optical reflection of surface of silicon implanted with Ag⁺ ions at low energy of 30 keV in a wide dose range 5.0 · 10¹⁴-1.5 · 10¹⁷ ion/cm² was studied in parallel with electron microscopy observation of the samples. It was found that with increasing ion dose of irradiation, the reflection intensity in the UV region of the Si spectrum decreases monotonically due to amorphization and macrostructuring of Si near-surface layer. In the long-wavelength region of the reflection spectra, a selective band with a maximum near 830 nm is recorded due to the plasmon resonance of ion-synthesized Ag nanoparticles.

Surface-enhanced Raman scattering (SERS) nanotags as an ultrasensitive nanoprobe is becoming popular for the detection of biomarkers. Herein, antibody-conjugated gold nanoparticles (AuNPs) were used to target LMP2A in an LMP2A-infected CNE2 cell line. SERS maps showed that the LMP2A was distributed around the cell, which was consistent with the results of immunofluorescence staining in the previous report. This location could be due to the specific binding of the bioconjugated nanotags to the receptors on the cell surface. However, the CNE2 cell line without LMP2A-infected showed no detectable signal at 1044 cm^{- 1} . The results demonstrated the potential feasibility of AuNPs nanotags as highly sensitive probes conjugated at the subcellular level for detection and localization of cancer markers in nasopharyngeal carcinoma (NPC).

The impact of γ-radiation¹³⁷Сs (doses of 1 and 3 Gy), low-intensity laser radiation (λ = 670 nm, 5.3 or 10.6 J/cm²), as well as the influence of consecutive laser and γ-radiation on peripheral blood and blood cells (erythrocytes, leukocytes, lymphocytes, granulocytes) was studied by analyzing of the number of blood cells, blood absorption spectra and activity of antioxidant defense enzymes. Two series of experiments were performed on four groups of rats. The rats of the control group (group 1) were not exposed to γ or laser radiation. In the experimental groups, single irradiation of the whole body of rats with γ-radiation (group 2), three- or four-day over-vein irradiation of blood in the tail vein by low-intensity laser radiation (group 3), successive three- or four-day irradiation of blood by laser and then a single irradiation of the whole body with γ-radiation (group 4) were performed. It was shown that changes in the blood cell content in the experimental groups are accompanied by changes in the spectral characteristics of the blood and the activity of antioxidant defense enzymes. The radioprotective effect of low-intensity laser radiation manifested as an increase in the average number of leukocytes and lymphocytes in the group as compared with the post-radiation, as well as an increase in the activity of antioxidant protection enzymes. The possibility of using low-intensity optical radiation for correction of hematological disorders caused by ionizing radiation is discussed.

Wastewater from the dye industry is typically analyzed using a standard method for measurement of chemical oxygen demand (COD) or by a single-wavelength spectroscopic method. To overcome the disadvantages of these methods, ultraviolet-visible (UV-Vis) spectroscopy was combined with principal component regression (PCR) and partial least squares regression (PLSR) in this study. Unlike the standard method, this method does not require digestion of the samples for preparation. Experiments showed that the PLSR model offered high prediction performance for COD, with a mean relative error of about 5% for two dyes. This error is similar to that obtained with the standard method. In this study, the precision of the PLSR model decreased with the number of dye compounds present. It is likely that multiple models will be required in reality, and the complexity of a COD monitoring system would be greatly reduced if the PLSR model is used because it can include several dyes. UV-Vis spectroscopy with PLSR successfully enhanced the performance of COD prediction for dye wastewater and showed good potential for application in on-line water quality monitoring.

Different types of fireworks are analyzed using the laser-induced breakdown spectroscopy (LIBS) technique. The system employed for spectral acquisition consists of a Nd:YAG laser (532 nm, FWHM = 4 ns) and an Andor Mechelle ME 5000 echelle spectrometer. The presence of Ba, Ca, Mg, Fe, Na, Sr, Si, and Al is identified in the LIBS spectra of different fireworks. These elements can mix easily into the surroundings and thus pollute the environment. In combination with LIBS, multivariate statistical methods, such as principal component analysis and partial least square discriminant analysis, are employed for qualitative classification, regression, and prediction purposes. These methods show good applicability for the classification and prediction of a large data set.

The interaction of the functional groups of the polyurethane foam sorbent Penopurm^® with the cations of some 3d-metals in the process of their extraction from aqueous solutions have been studied by atomic emission spectrometry, UV/Vis and vibrational IR spectroscopy and quantum chemical simulations within density functional theory. It was established experimentally that in the range of pH 5-7 Penopurm^® absorbs the cations of the 3d-metals from aqueous solutions. Some spectral criteria have been revealed that allow one to draw a conclusion about the predominant interaction of Ni²⁺ ions with different fragments of the polyurethane foam structure.

We propose a tunable eight-wavelength terahertz modulator based on a structure of triple triangular lattice photonic crystals by using photonic crystals in the terahertz regime. The triple triangular lattice was formed by nesting circular, square, and triangular dielectric cylinders. Three square point defects were introduced into the perfect photonic crystal to produce eight defect modes. GaAs was used as the point defects to realize tunability. We used a structure with a reflecting barrier to achieve modulation at high transmission rate. The insertion loss and extinction ratio were 0.122 and 38.54 dB, respectively. The modulation rate was 0.788 dB. The performance of the eight-wavelength terahertz modulator showed great potential for use in future terahertz communication systems.

The wide field view (WFV) sensor on-board GF-1 satellite can acquire multi-spectral data with moderate spatial resolution, which holds great potential for monitoring the Earth’s surface. This study assesses WFV data through cross-comparison of spectral band reflectances and vegetation indices with Landsat-7 Enhanced Thematic Mapper plus (ETM+) data. The four vegetation indices considered in this study are the normalized difference vegetation index (NDVI), the enhanced vegetation index (EVI), the ratio vegetation index (RVI), and the soil adjusted vegetation index (SAVI). The R² between the WFV and ETM+ data were 0.82, 0.89, 0.92, and 0.80 for the blue, green, red, and near-infrared bands reflectance, and 0.90, 0.84, 0.83 and 0.91 for NDVI, EVI, RVI, and SAVI, respectively. The results displayed a high correlation between the spectral reflectances and vegetation indices of the two sensors’ data, which indicated the reliability of the WFV data. Furthermore, the WFV data were better than the ETM+ data with regards to spatial and temporal resolutions.

An effective spectroscopic method for estimating the degree of filling (porosity) of polymeric materials, the average size and the size distribution of the scattering particles of the filler within the polymer matrix, their anisometry and the degree of orientation is proposed. The obtained spectral data are in good agreement with the results of optical and electron microscopy methods.

The Varshni parameters of the dependence of the bandgap energy on temperature in the range of 10-313 K, as well as the temperature dependence of the spin-orbit splitting energy have been calculated on the basis of the experimental data obtained for the InAs_0.88Sb_0.12 active layer. It has been found that for LEDs based on the InAs_0.88Sb_0.12/InAsSbP heterostructures amplified luminescence is observed in the temperature range of 10-35 K. The sharp drop in the intensity of radiation of the InAsSb/InAsSbP LEDs at temperatures higher than 32 K is due to the intensive growth of the CHCC process of the Auger-recombination, while for temperatures below 35 K the CHSH process is the dominant Auger recombination process.

For active-pulse vision systems with illuminating pulses of triangular and trapezoidal forms the range-energy profiles (REP) of the signal have been obtained with a change in the time delay between the leading front of the strobe pulse and the illuminating pulse. It is established that if the duration of the illuminating pulse Δt_las is less than or equal to the duration of the image convertor strobe pulse Δt_IC, the expressions for the characteristic distances coincide with the case of pulses of a rectangular shape and they can be used to determine the distance to objects. In the case of triangular-shaped illuminating pulses at Δt_las > Δt_IC the REP acquires a bell-like shape. For pulses of a trapezoidal shape the REP has a bell-shaped shape with or without a plateau-like region. An empirical method for determining the characteristic distances to the maximum of the REP and the boundary points of the plateau-like region which are then used to calculate the distance to the object has been proposed. With the use of calibration constants a method for determining the distance to the object has been proposed, and its operability is experimentally confirmed.

The possibility of using phosphors of the coumarin series in luminescent converters for correcting spectra of LED light sources is investigated. Fine tuning of the emission spectra of phosphors in polymer matrices has been obtained by introducing nonionic surfactants into the matrix. A method for estimating the photostability of luminescent filters is proposed and the photostability parameters are determined.

The nanocrystals of rare-earth garnets, Y₃Al₅O₁₂ and Lu₃Al₅O₁₂, and perovskite GdAlO₃ highly-doped (10-20 at.%) with Eu³⁺ ions are synthesized by the solution combustion technique and subsequent annealing in air at 800 and 1300 °С. The structure, morphology and composition of obtained materials are studied. Under UV excitation, these materials exhibit intense red luminescence. For Eu:GdAlO₃, CIE 1931 color coordinates of the luminescence are (0.632, 0.368), dominant wavelength is 599.6 nm, and color purity is >99%. Judd-Ofelt parameters, luminescence branching ratios and lifetime of the⁵D₀ state of the Eu³⁺ ions are determined. For 10 at.% Eu:GdAlO₃, the luminescence quantum yield reaches 74% and the⁵D₀ lifetime is 1.4 ms. The synthesized materials are promising for red ceramic phosphors.

The features of plasmon-polaritons (PPs) exited on the boundary of dielectric and a hyperbolic metamaterial are investigated for the case when the optical axis is oriented at an angle to the interface. It is shown that the PP phase velocity in the metamaterial is directed under a certain angle towards the boundary. The possibility is established and the conditions are found for localization of the plasmon-polaritons near the boundaries of the hyperbolic metamaterials of both I and II types. It is grounded that the surface PP localized near the isotropic dielectric-hyperbolic metamaterial boundary has the transverse spin moment whose magnitude depends on the wavelength of the exiting radiation, the orientation of the optical axis of the hyperbolic metamaterial, and the dielectric properties of the boundary media.

The samples of nanoheteroepitaxial structures with Ge quantum dots in a GaP matrix on Si substrates have been grown in two structural schemes using a liquid-phase epitaxy method with pulsed cooling of the substrates. The photoluminescence spectra of the samples at temperatures of 77 and 300 K are measured under excitation by laser radiation with λ = 4880 and 5145 Å. Conclusions are made about the factors that affect the spectrum and intensity of radiation of the nanostructures with quantum dots. It is found that in order to reduce nonradiative recombination in the multilayer p-n structures, it is necessary to create arrays of quantum dots in the volume of p- and n-regions, rather than in the central part of the depletion layer of the p-n junction. It is shown that the theoretical energy values for Ge quantum dots of calculated sizes are comparable with the energy of their photoluminescence maxima.

Two simple spectrophotometric methods were developed for determination of empagliflozin and metformin by manipulating their ratio spectra with application on a recently approved pharmaceutical combination, Synjardy^® tablets. A spiking technique was used to increase the concentration of empagliflozin after extraction from the tablets to allow its simultaneous determination with metformin. Validation parameters according to ICH guidelines were acceptable over the concentration range of 2-12 μg/mL for both drugs using constant multiplication and spectrum subtraction methods. The optimized methods are suitable for QC labs.

A new thiophene derivative, 3-bromo-2-methyl-5-(4-nitrophenyl)thiophene (2), was synthesized through the Suzuki coupling reaction of 4-bromo-5-methylthiophen-2-ylboronic acid (1) and 4-iodonitrobenzene, and its structure was confirmed by nuclear magnetic resonance (NMR), low and high resolution mass spectrometry (HRMS), Fourier transform infrared spectroscopy (FT-IR), and X-ray investigations of the crystal structure. The FT-IR spectra (4000-400 cm^-1), Raman spectra (4000-100 cm^-1), and theoretical vibrational frequencies of this new substance were investigated. Its theoretically established geometric parameters and calculated vibrational frequencies are in good agreement with the reported experimental data. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies and other related parameters of the compound were calculated. The ionization potentials given by the B3LYP and HF (Hartree-Fock) methods for this new compound are -0.30456 and -0.30501 eV, respectively.

The interaction between rhodamine 6G (Rh6G) and cerium sulfate was studied by the fluorescence quenching method. In a sulfuric acid medium, the interaction of Ce(IV) with Rh6G results in Rh6G fluorescence quenching. The maximum excitation wavelength (l_ex) and the maximum emission wavelength (l_em) are 530 nm and 555 nm, respectively. A good linearity between the relative fluorescence intensity (ΔF) and Ce(IV) was observed in the range ~0.12-1.08 mg/mL. The detection limit was 1.4´10^-3mg/mL. The optimum reaction conditions, influencing factors, and effect of coexisting substances were investigated in the experiment. We found that the concentration of Rh6G was 3.2´10^-6 mol/L, and the fluorescence intensity was maximum.

We investigate two imidazolium zwitterionic salts, 1,3-dimethylimidazolium-2-carboxylate and 1-butyl-3-methylimidazolium-2-carboxylate, together with 1-butyl-3-methylimidazolium acetate using X-ray photoelectron spectroscopy. The electronic environment of each element for the two zwitterionic salts is analyzed. Due to the electron-withdrawing effect of the imidazolium cation, the binding energies of C_carboxyl 1s and O 1s for zwitterionic salts are higher than those of 1-butyl-3-methylimidazolium acetate. The impact of the alkyl chain length on the charge distribution is also illustrated. It suggests that the electron-withdrawing effect of the imidazolium cation decreases along with the increasing of the alkyl chain length.

A novel chemosensor exhibiting highly selective recognition of Cd ²⁺ over other metal ions with significant fluorescence quenching was designed and synthesized by a click reaction of dialkyne and indole azide precursors. The compound was identified by¹H NMR,¹³C NMR, MS, and UV-vis spectroscopy. The fluorescence quenching phenomenon was observed with the addition of Cd ²⁺ . The reaction conditions, including the selectivity, the amount of Cd ²⁺ , reaction time, and temperature, were optimized in the article. The product exerted highly selective fluorescence change in the presence of Cd ²⁺ over other metal ions, such as Li⁺ , Na⁺ , K⁺ , Pb²⁺ , Ni²⁺ , Zn²⁺ , Mn²⁺ , Hg²⁺ , Cr³⁺ , Cu²⁺ , and Fe³⁺ . Under the optimal conditions, a linearly proportional relationship between fluorescence intensity and the concentration of Cd²⁺was revealed in the range from 0 to 7.226×10^{- 5} M. The limit of detection was 2.69 μM. The results suggest that the substance synthesized with 2-methylindole is a novel and quick detector for Cd ²⁺ .

In the present study, Tauc-Lorentz and Urbach tail assisted Cody-Lorentz models were intuitively derived, explained, and employed to simulate the imaginary dielectric function of the atomic layer deposited (HfO₂)_x(ZrO₂)_1-x in the energy range of 0.7-9.3 eV. A fitting procedure is carried out using the Levenberg-Marquardt method for minimizing mean square errors. Both models support the experimental data derived by vacuum ultraviolet spectroscopic ellipsometry. For a zirconium content of 60 and 75%, a weak absorption profile is observed in the visible region and elaborately explained by the Lorentz oscillator model. In order to calculate the band gap of different compositions, Cody plots and Tauc plots are presented. The results show that the Cody-Lorentz model is more accuracy due to its exponential absorption below the band gap energy and modified density of states.

A number of phosphate rocks and organo-mineral P fertilizers was analyzed comparatively by laser-induced breakdown spectroscopy (LIBS) in both single- and double-pulse modes associated with two chemometric methods, i.e., principal components analysis (PCA) and partial least squares regression (PLSR). PCA was demonstrated to be a valuable method for the identification of spectral differences between similar samples with only minor compositional differences. The raw and normalized LIBS spectra were able to provide effective identification and discrimination at a 95% confidence level and an in good agreement with the reference concentrations. Results obtained confirm the promising potential of LIBS for the rapid classification of P fertilizers in situ.