Absorption, fluorescence and phosphorescence spectra of metal complexes of 4-tert-butylphenyl substituted tetra(1,4-diazepino)porphyrazine MPADz₄Ph′₈ (M = Mg, Zn; PA — porphyrazine, Dz — diazepine, Ph — phenyl, Ph′ — para-tert-butylphenyl) in DMF were recorded at 293 and 77 K. The absorption band Q(0–0) both for MgPADz₄Ph₈′ and ZnPADz₄Ph₈′ had no signs of splitting, i.e. corresponds to the monomeric form. The singlet–triplet energy interval which is 4730 and 4830 cm^–1 for Mg and Zn-complex, respectively, was determined from the fluorescence and phosphorescence spectra. The fluorescence quantum yield and duration were measured; the rate constant of the S_1,2→S₀ radiative transition and the total rate constant of non-radiative deactivation of the state S_1,2 were determined; the rate constant of internal conversion was estimated. Calculations of the geometry of the MgPADz₄Ph₈ conformers (in the 6H tautomeric form) were carried out by the use of the density functional theory (DFT method), in the PBE/TZVP version. It is found that the conformer of the S_4v (D_2d) symmetry has the lowest energy. It was shown that the non-planar structure of the diazepine ring induces small but noticeable off-plane distortions in the central, porphyrazine part of the MgPADz₄Ph₈ molecule . This feature correlates with the observed at 293 K Stokes shift of 400 cm^-1 for the Mg-complex and 350 cm^–1 for the Zn-complex, while the shift is about 50 cm^–1 in metal phthalocyanines. It follows from the INDO/Sm calculations of the excited electronic states of MgPADz₄Ph₈ that the energy of Q-state 15200 cm^–1 corresponds very well to the observed 14800 cm^–1. Intensive structureless absorption at λ = 330—450 nm, an analogue of the Soret band, with maxima at ~25000 and ~29000 cm^–1 was compared primarily with two intense electronic transitions, the calculated energies of which were 24100 and 31500 cm^–1, and the shoulder on the long-wave side of the Soret band at ~23000 cm^–1 was compared with the transition having calculated energy of 23800 cm^–1.

We studied the Raman scattering and infrared absorption spectra of polymer films of polyvinyl alcohol with additions of salts of nitrate, perchlorate, and lithium tetraftorborate. It is shown that the microstructure and character of the dynamic interactions of the particles in them largely depend on the nature, form, and charge state of the molecular anion.

The temperature dependence of the electronic absorption spectra of the 5,10,15-triarylcorrole family solutions in ethanol was studied in the temperature range 288—328 K. Corrole molecules in ethanol was found to be as a mixture of the free base and deprotonated forms, with their proportion determined by donating-accepting properties of peripheral substituents. It was established that temperature rise leads to the deprotonation of the free base molecules. Deprotonation process is governed by Van’t Hoff equation with activation energy Е_а = 2.0 kcal/mol, which was found to be the same for all the studied compounds within the experimental error. It was supposed that temperature influences deprotonation indirectly, by adjusting the dielectric constant of ethanol. Decrease in the dielectric constant with temperature rise shifts the acidbase equilibrium to the formation of the deprotonated form.

Spectral-luminescent characteristics of solid solutions GdF₃:Pr:Yb and YF₃:Pr:Yb synthesized by the crystallization from the melt are investigated. Down-conversion luminescence of the Yb³⁺ ions in the region of ²F_5/2 → ²F_7/2 transitions at 445 nm excitation was studied. Energy transfer coefficient from Pr³⁺ to Yb³⁺ ions was <80% for the ratio of Pr/Yb concentrations 0.5/10.0 and 1.0/10.0 for GdF₃, and 0.5/10.0 for YF₃. High efficiency of nonradiative energy transfer does not lead to high values of absolute quantum yield of luminescence of Pr³⁺ and Yb³⁺ ions in the region of maximum photosensitivity of crystalline silicon. The quantum yield does not exceed 1 % for the intrinsic luminescence Yb³⁺ and 4 % of the total luminescence in the range 800—1050 nm (for the ratio of Pr/Yb concentrations 0.5/1.0 in the GdF₃ matrix). The low quantum yield is a consequence of the complex pattern of energy exchange between ions Yb³⁺ and Pr³⁺, which is largely influenced by the energy proximity of the ¹G₄ state of the ion Pr³⁺ and ²F_5/2 of the ion Yb³⁺ in these matrices and by the cross-relaxation between the transitions ³P₀ → ¹G₄ of the ion Pr³⁺ and ²F_5/2 → ²F_7/2 of the ion Yb³⁺. The energy proximity results in an additional channel of non-radiative decay of the excited state of the ions Yb³⁺, and the cross-relaxation leads to an increase in the lifetime of the ³P₀ state of the ion Pr³⁺.

Methods for detecting and recovering drift of parameters in random samples are investigated. These methods were applied both for model problems and for real experimental data in which drift was present. For the experimental data, the drift was recovered and the dependence of the detector failure probability on time was obtained with and without drift.

We explore the attack of unambiguous state discrimination on the line of quantum key distribution utilizing time coding of the information on the basis of the protocols BB84 и B92. We obtain the probability of discriminating all signal states in the quantum communication channel and establish the parameters of the corresponding quantum measurement.

The 3309, 3232, and 3185 cm^{- 1} are a series of peaks defined as the 3309 cm^{- 1} -series peaks of the functional group absorptions in the mid-infrared region of gem corundum samples, in particular, the blue sapphires. In this study, the 3309 cm^{- 1} -series peaks were attributed to -Ti-OH stretching. However, the application of revealing these series peaks is still limited because the mechanism of those peaks during the heating process has yet to be clarified. This study showed that the characteristics of the peaks depend strongly on the TiO₂ content in the sapphire samples. Energy dispersive X-ray fluorescence (EDXRF) spectrometry indicated that the samples with Ti content >0.02 wt.% usually show the 3309 cm^{- 1} -series peaks with strong intensity. In addition, the X-ray absorption spectra (XAS) revealed that the oxidation state of Fe is Fe³⁺ while Ti is Ti⁴⁺ for every heating temperature. The UV-Vis-NIR optical absorption showed that the alteration of the bands at 580 and 710 nm, defined as the Fe³⁺/Ti⁴⁺ pair, was related directly to the atmospheric heating conditions. In contrast, the intensity of the 3309 cm^-1-series peaks gradually decreased with increase in heating temperatures in any given atmosphere. This is a result of the mechanism of the bonding between Ti and/or Fe atoms and -OH in blue sapphire structures caused by the heating.

We investigate the mechanism of mica dehydroxylation using IR spectroscopy, X-ray and thermodynamic analysis, as well as the kinetic, quantum-mechanical, and quantum –chemical methods. The process of degidroxylation is established as a process of the localization of a proton in a system of two atoms of oxygen and a proton between them. We offer a model in which a proton of a hydroxyl group is placed in “a double potential well”. The model allows us to reveal the main regularities of the process of dehydroxylation of minerals. As a result of heating, the proton energy increases and the transparence of the barrier grows too. The transition possibility of a particle through the barrier owing to a tunnel effect is considered. The change of this probability defines the process of dehydroxylation of a system.

The paper presents the results of a study of the transformation of the structural defects, hydrogen state, and electro-physical properties of silicon treated in a hydrogen plasma. It is established that after the treatment of plasma (150°C) the bands with their peak maxima at 2095 and 2129 cm^–1 are observed in the Raman spectra. These peaks are associated with scattering on the vibrations of Si-H bonds. The subsequent heat treatment at 275°C results in the appearance of a band at 4153 cm^–1 related to the molecular hydrogen oscillations in a gaseous state. From a comparison of the data of Raman spectroscopy and scanning probe microscopy, it is found that as a result of the hydrogenation structural defects (platelets) with an average size of 43 nm and a surface density of 6.5 · 10⁹ cm^–2 are formed. Their appearance is due to the precipitation of hydrogen with the formation of Si-H bonds. After the heat treatment, inclusions filled with molecular hydrogen with an average size of 115 nm and a surface density of 1.7 · 10⁹ cm^–2 are formed. It is shown that the concentration of free charge carriers does not change after the plasma treatment and subsequent heat treatment.

The spectrum of orange and red photoluminescence of copper iodide was divided into four components with λ_max ≈ 625–635 (O₁), 635–655 nm (O₂), 725–735 nm (K₁) and 735–755 nm (K₂). Such division may be explained by the possible association of the corresponding glow centers (GC) with donor-acceptor pairs (DAP) responsible for CuI edge luminescence. The generation-recombination scheme of red-orange luminescence based on the Auger interaction between the GC and the DAP was developed. It was found that the role of GC for red luminescence of CuI perform their own defects in the form of interstitial copper. It was shown that luminescent characteristics of copper iodide may be controlled by the crystal annealing (in the vapor of iodine, in a vacuum), or by doping with lithium or by saturation of the samples with copper in the process of electrodiffusion.

Cerium-doped ZnO nanopowders were synthesized using the simple refluxing technique. The synthesized samples were characterized by X-Ray diffraction, which confirmed their hexagonal structure. No additional peaks due to the interstitial incorporation or substitutions of Ce⁴⁺ ions into the ZnO lattice were observed. Ce 3d_3/2 and 3d_5/2 had well-separated orbits of ∆ = 18.26 eV. The observed spin-orbit splitting as well as the separation between 3d_5/2 peaks by 16.47 eV were in good agreement with those reported. The presence of 917.85 eV also confirmed the presence of Ce⁴⁺ ions. Raman studies showed that for Ce-doped ZnO the nonpolar interaction E_2H grew strong and had a dominant intensity.

The spectra and structure of the near-surface plasma formation resulting from the two-pulse laser effect on a titanium target in the air at wavelengths of 532 and 1064 nm were experimentally investigated. The specific mass removal and plasma plume luminosity were measured depending on the time interval between laser pulses and their order. The dependences of the temperature of the laser plasma and the concentration of charged particles on the parameters of paired laser pulses were established for laser radiation power densities of q_1.064 ≤ 3.1 · 10 9 W/cm², and of q_0.532 = ≤ 2.7 · 10 9 W/cm² at wavelengths of 1064 and 532 nm, respectively. It is shown that optimal conditions for recording the erosion plasma spectra are ensured at the leading effect of second harmonic radiation with a time interval between laser pulses of 4–5 μs, and for specific mass removal — with an interval of 3–6 μs. That results are important for the efficiency enhancement of the laser emission spectral analysis and laser-plasma processing of materials.

The derivative spectrophotometric method was established for simultaneous determination of dexamethasone and cytarabine (cytosine arabinoside). Measurements were made in the zero-crossing wavelengths at 268.0 nm (first derivative) and 264.0 nm (third derivative) for determining dexamethasone and cytarabine, respectively. The calibration graphs were linear in the concentration ranges 0.10 to 10 µg/mL of dexamethasone and 0.25 to 50.0 µg/mL of cytarabine. The limits of detection 0.08 and 0.10 µg/mL and relative standard deviations 3.0 and 1.0% were obtained for dexamethasone and cytarabine, respectively. The possible interfering effect of other substances was also studied to investigate selectivity of the developed method. The proposed method was applied satisfactorily for the simultaneous determination of both drugs in the pharmaceutical formulation and biological fluid samples.

A simple and sensitive spectroflourimetric method has been proposed for the determination of the antitumor agent letrozole in tablets, spiked human plasma, and rat brain tissue homogenates. Our method involves measuring the native fluorescence of letrozole at 590 nm upon excitation at 239 nm as indicated upon scanning its three-dimensional spectrum. Various experimental parameters were intensively studied and the method was validated as per ICH guidelines. The calibration curve was linear over the concentration range 5-160 ng/mL, with limit of detection 1.36 ng/mL. It was successfully applied to the analysis of letrozole in Femara® tablets with mean recovery 99.35 ± 1.49% and was further applied to study the alkaline degradation kinetics of letrozole. The pseudo first order rate constant and half-life were calculated. Moreover, Successful application of our proposed procedure was carried out on spiked human plasma and rat brain tissue samples. Linear ranges were found to be 5-30 and 10-130 ng/mL, with detection limits 1.25 and 1.71 ng/mL for plasma and brain samples, respectively. Thanks to the method's simplicity, selectivity, and high sensitivity, it can be used for routine analysis in quality control laboratories and for further clinical investigations involving letrozole.

We study the fluorescent characteristics of eosin molecules in solutions of bovine serum albumin at various pHs. It is established that the quenching of eosin fluorescence with an increase in its concentration is due to two competing processes: the binding of BSA molecules to eosin molecules and the formation of associates of dye molecules. The degree of association, the structure and thermodynamic parameters of dimers in buffer and BSA solutions at different pH values are determined. Variations in the pH of eosin buffer solutions lead to the change of all these characteristics. It is shown that the formation of eosin associates in BSA solutions leads to a decrease in the dynamic quenching constant of eosin fluorescence, which is proportional to the pH of the solution.

We considered the fundamental principles of terahertz high resolution spectroscopy, based on the effect of free damping polarization, and the spectrometer in which this effect is realized in the regime of phase switching of radiation influencing gas. This approach is characterized by high selectivity and sensitivity, quickness of analysis, and safety. We analyzed the possibility of the use of terahertz high resolution spectroscopy in such agricultural applications as the component analysis of grain at its thermal decomposition. Measurements of the subterahertz spectra of samples of oats and barley at their thermal decomposition were carried out, and the absorption lines of various organic substances were identified.

The assignment of the signals of the hydrogen and carbon atoms nuclei in the spectra of 15-substituted steroids of the androstane and pregnane series was carried out by two-dimensional NMR spectroscopy methods.

The generation of high-order harmonics and single attosecond pulses via the asymmetric polarization gating technology has been theoretically investigated. It is shown that when the two circularly polarized laser fields are asymmetric in amplitude and phase, not only can the modulations of the harmonic spectrum be decreased, but also the efficiencies of the harmonics can be enhanced. As a result, a super-continuum with the bandwidth of 85 eV, contributed by the single harmonic emission peak and the near-single short quantum path, can be obtained. Finally, through the Fourier transformation of the selected harmonics on this supercontinuum, a near single attosecond pulse with a full width at half maximum of 52 as can be obtained.

Using a method based on the spectrophotometric analysis of the liquids remaining after washing ceramic granules, the type of impurity was determined, the wavelength for measuring the impurity was established, and the type of cell (polystyrene or quartz) was analyzed. The absorbance of the samples was measured at wavelengths between 190 and 1100 nm. The results showed that both cuvette types are useful; however, the greatest absorbances were detected using quartz ones at low wavelengths around 190 nm. The comparison of absorption spectra from the samples, centrifuged and non-centrifuged, enabled us to define the impurities as small apatite particles.

The spin-lattice and spin-spin relaxation times Т_1,2 depending on viscosity and concentration of asphaltenes+resins in oils have been studied using proton magnetic resonance relaxometry, in particular, for the Bach Ho (JV “Vietsovpetro”) oil deposition, and the relating equations are deduced. The correlation ηТ_1,2 = соnst/Т has been refined. The viscosity ν = η/ρ in these oils is exponentially proportional to the concentration of asphaltenes+resins.

We have developed an approach and a design for the snapshot registration of multispectral information based on a dispersive polychromator with mirror objectives. By numerical simulation it is shown spot size for 11 spectral bands within 400—700 nm range when displaying the points in the center and on the periphery of the object field does not excess 15 µm for a camera mirror with a focal length of 100 mm. Due to the use of simple optical elements, the schematic solution can serve as the basis for the creation of low-cost devices for a wide range of imaging spectroscopy applications.

The efficiency of the LIBS signal enhancement by deposition of gold nanoparticles prepared by laser ablation in acetone on the surface of the analyzed sample has been studied. The characteristics of the laser plasma generated on the steel surface before and after deposition of the nanoparticles have been compared. It has been established that deposition of nanoparticles increases the plasma volume and lifetime, but does not affect the erosion of the material. The deposition of nanoparticles results in the enhancement of the spectral lines intensities depending on the zone of the plasma plume selected for analysis: the signal enhancement grows with the distance from the sample.

The thin films (~100 nm) based on 2-phenyloxybenzoate terbium(III) doped into a polymer matrix have been obtained. The terbium content in the mixture was varied from 0 to 11 wt.%. The films were prepared on K8 glass by spin coating from a chloroform solution. The presence of a weak antireflection effect was established using light transmission spectra of the films on the glass. According to the excitation and luminescence spectra, there is reemission of light from the spectral range of 240–330 nm to the range of 480–640 nm, where a series of narrow luminescence peaks characteristic of the Tb³⁺ ion is observed. The effect of the films on the efficiency of three-stage solar cells has been studied.

The effect of halogens in the compound of carbazolyl-containing oligomers on the information properties of recording media for the photothermoplastic method of recording holograms is studied. An increase of the photosensitivity of such media with the presence of halogens in their composition has been observed. Using the photoactivated EPR method, it is shown that in the presence of halogens, the lifetime of the photogenerated charge pairs increases. This is associated with an increase in the probability of photogeneration of the charge pairs in the triplet state for the modified oligomers compared to their counterpart. It is assumed that the modification of photoconductive polymers with halogens is one of the ways to increase their photosensitivity, which can be used for other practical applications (photovoltaics, molecular electronics).

A method for the quantitative analysis of trans fatty acids (TFAs) in cooked soybean oil using terahertz (THz) spectrum is developed. The THz spectra of three groups of soybean oil samples that were cooked at different temperatures for various times were measured using a terahertz time-domain spectrum system (THz-TDS）with frequency range of 0.2-1.5 THz. A partial least squares (PLS) regression model based on the whole THz spectrum was constructed to predict the TFAs content in the cooked soybean oil samples. To reduce noise and improve the prediction accuracy of the model, a subinterval PLS (sub-PLS) model based on a part of the THz spectrum was constructed. This sub-PLS had high accuracy in predicting the TFAs content in cooked soybean oil samples (R = 0.987 and RMSECV = 0.956).

We analyze the performance of the surface-enhanced Raman spectroscopy (SERS) substrate based on high-density gold nanostar nanoparticle (GNS) arrays assembled on the gold film and embedded in the human skin tissue as a surrounding medium. A self-assembled monolayer (SAM) of 3-aminopropyltriethoxysilane (APTES) is used for immobilizing GNSs on the Au film. The GNS-Au film and GNS-GNS coupling in the gap regions and also the GNSs interparticle coupling at their branches are observed, so the GNS arrays show more field enhancements and the sensitivity of the GNS sensor can be increased further. When the SERS substrate based on the GNS arrays is excited by a 785 nm laser line, a maximum enhancement factor (EF) of 10⁹ is observed. It is demonstrated that the normalized EF depends on the geometry of the GNSs, the thickness of the Au film, and the separation distance between the cores of the GNSs.

Irbesartan is a class II crystalline drug according to the Biopharmaceutical Classification System, the solubility of which in water is less than 0.1 mg/mL, and thus it possess a challenge for developing methods of its analysis. Hydrotrophy is one such phenomenon in which water-soluble agents enhance the solubility of hydrophobic compounds, precluding the use of toxic organic solvents. Among various hydrotropes screened, 1 M sodium acetate showed solubility enhancement of irbesartan by 33 times. After checking the effect of molarity from 0.5 to 4 M, 1 M sodium acetate showed characteristic absorption peaks and obeyed the Beer-Lambert law for 10-20 μg/mL solution of irbesartan hydrotrope mixture. Based on the plot of the concentration v/s absorbance, the calibration curve equation was found to be y = 0.040x - 0.013 with a correlation coefficient of 0.998. The LOD and LOQ values were found to be 0.3 and 1. The proposed method was validated for accuracy and precision at three suitable levels of concentration, i.e., 10, 14, and 18 μg/mL, for which the RSD was found to be 0.09, 0.07, and 0.1%, respectively. It was found that the method is robust and specific in the presence of other excipients and shows RSD values of 0.4, 0.5, and 0.6%, which are within acceptable limits.

The present work reports the quantitative analysis of chromium along with other constituents in the soil of the Jajmau industrial area, Kanpur, India using laser-induced breakdown spectroscopy (LIBS) and total reflection X-ray fluorescence (TXRF). High concentrations of chromium have also been demonstrated in wheat and mustard plants in this study.

Seven Indian copper coins of the Kushan Period (1-3^rd century C.E.) were studied by multi-analytical techniques like WD-XRF, XRD, and FESEM-EDX to understand coin composition and the metallurgical process of fabrication. Analytical results reveal a compositional gradient in the distribution of elements between the external surface and the inner core of the coins, and the coins show isolated patches of surface mineralization leading to the formation of copper oxides, magnesium silicate, and silica. The analysis also showed the probable use of sulfide ore of copper for smelting and poor workmanship for this hoard. The impurities like sulfur, iron, silica, etc. could not be removed due to low firing temperature and improper poling during smelting. Striations have formed in the coin interior, with grain boundaries showing micro-cracks due to stress like punching or hammering with the die. The coins under study are a single-phase copper with associated impurities of Si, Al, P, and Mg in all coins and black spots of copper sulfide in coin inner core.

The reaction of terephthalaldehyde, p-chloroaniline, and diethyl phosphite in ethyl alcohol solution yields a new crystal (1), CCDC:1405044. This compound is characterized by X-ray single-crystal diffraction, IR, elemental analysis, ESI-MS, and ¹H and ¹³C NMR. Compound 1 crystallizes in the triclinic system, space group P-1 with a = 11.0444(4) Å, b = 12.6468(4) Å, c = 12.7657(4) Å, V = 1627.46(9) ų, Z = 2, C₂₈H₃₆Cl₂N₂O₆P₂, M_r = 629.43, D_c = 1.284 g/cm³, μ = 0.339 mm^-1, F(000) = 660, GOOF = 1.101, final R = 0.0875 and wR = 0.1082 for 7381 observed reflections (I > 2σ(I)). The X-ray analysis reveals that the planes of p-chloroaniline and terephthalaldehyde form a dihedral angle of 87.54(0.28)°. In the crystal of compound 1, P atoms have tetrahedral geometries, made up by a double-bond O atom, one C_α atom, and two O-ethyl groups. Besides, C_α atoms are responsible for the existence of the optical activity. Five intramolecular hydrogen bonds helping to stabilize the crystal structure are observed. The interaction between compound 1 and DNA/BSA is also studied.