This review is devoted to studying the state and development tendencies of ET AAS for the last 25 years (from 1990 to 2016) in the direct determination of Cu, Zn, Pb, Cd, Mn, Se, As, Cr, Co, Ni, Al, and Hg in the body fluids: blood, urine, saliva, and breast milk.

We investigated the temperature and phase dependence of the Raman spectra (RS) and the molecular relaxation characteristics of nitrate ion oscillations in the (1 -x )RbNO₃ + xAl₂O₃ composite at different concentrations of Al₂O₃ nanopowder. It is shown that at the filler concentration x = 0.6 the vibration relaxation time n₁(А) in the high-temperature phase of RbNO₃-II does not change significantly as compared with the phase of RbNO₃-III, which indicates the stabilization of the cubic phase of RbNO₃-III. Besides, at high concentrations of the filler the salt subsystem is in a highly disordered state and it is difficult to fix any structurally distinct states at the macro level.

We studied the peculiarities of the formation of silver nanoparticles (Ag NPs) under the intramolecular redox reaction of the Ag(I) complex with 4,6-di-tert-butyl-2,3-dihydroxybenzaldehyde isonicotinoyl hydrazone in organic solvents with high donor numbers (DN > 19). The stability of organosols was shown to be significantly dependent on the nature of the dispersion medium and on the presence of oxygen and water therein. The physico-chemical and morphological characterization of Ag NPs in organosols was carried out by absorbance spectroscopy, TEM, and AFM methods. The silver sol consisted of well-dispersed spherical nanoparticles with a size of 5-20 nm. A typical plasmon absorption band at 440 nm was observed for the Ag NPs. The Ag valence tautomeric complex was found to be a promising precursor of silver nanoparticles. The research demonstrated a high antimicrobial activity of synthesized Ag NPs in comparison with some standard antibiotics and silver-containing agents (MIC=0.007 µmol/ml).

We studied the rotational depolarization of the fluorescence of molecular systems of covalently linked fluorescein and oligonucleotides. The dependence of the fluorescence anisotropy of two nucleic acids on the temperature-to-viscosity ratio was measured in buffer solutions with different glycerol concentrations. It was shown that the experimental data can be satisfactorily explained within the diffusion model of an elongated molecular top with internal rotation. It was found that the coefficient of the internal rotational diffusion in all the cases was 1.5-2 times larger than the corresponding coefficient for the rotation around the axis of the oligonucleotide.

The synthesis and spectral characteristics of a new fluorescent N-allyl-4-iminodi(N-benzylacetamide)-1,8-naphthalimide (Zabe) sensor were reported. The ability of this new compound to detect anions was evaluated by spectrophotometrically monitoring the changes in the fluoresence intensity performed on its N,N-dimethylformamide (DMF) solution. Compared to other anions examined, only picrate (Pic^-) generated a prominent fluorescence quenching at 516 nm. No significant fluorescence change was observed in the presence of other anions. The emission quenching was due to the enhanced photoinduced electron transfer (PET) from the receptor to the excited state of the fluorophore upon the recognition of picrate. The chemosensor can be applied to the quantification of picrate with a linear range from 4.97×10^-6 to 6.82×10^-5 M and a detection limit of 6.6×10^-7 M. Most importantly, this sensor can be utilized for the spectroscopic detection of picratein the presence of other competing anions. Moreover, the response time of the chemosensor is less than 1 min.

The spectral and luminescence characteristics of three laser dyes incorporated into xerogel matrices preliminarily calcined under 700 °C were studied for the spectral range 600 - 700 nm. We revealed a stabilizing effect of these matrices on the dye molecules in the S₁ exited state. This effect manifested itself in the decrease of the non-radiating losses in this state and the increase of the quantum yield of the dye luminescence in calcined xerogel as compared with methanol.

The plasma is generated by focusing a long-pulse (80 μs) Nd:YAG laser on chromium-doped soil samples. The calibration curves are drawn using the intensity ratio of the chromium spectral line at 425.435 nm with the iron spectral line (425.079 nm) as reference. The regression coefficient of the calibration curve is 0.993, and the limit of detection is 16 mg/kg, which is 19% less than that for the case of a Q-switched laser In the method of long-pulse laser-induced breakdown spectroscopy, the laser-induced plasma had a temperature of 15795.907 K and an electron density of 2.988´10¹⁷ cm^-3, which exceeded the corresponding plasma parameters of the Q-switched laser-induced breakdown spectroscopy by 75% and 24% respectively.

It is shown that for active Q-switching the shape of the multimode Stokes pulse generated by an eye-safe Nd:KGd(WO₄)₂ laser with Raman self-frequency conversion depends on the inhomogeneity of the active medium pump. At the moderate non-uniform pump characterized by a higher population inversion in the center of the active element, the laser emits a short undeformed Stokes pulse with a duration of ~2.5 ns increasing with the growth of the length of the laser cavity. Upon varying the reflectivity of the output coupler in the range 5-45% the Stokes pulse energy (~11.5 mJ) changes slightly. A significant increase in the pump inhomogeneity leads to the distortion of the Raman pulse shape. Under the condition of the fundamental TEM₀₀ mode selection the degree of inhomogeneity of the pump is negligible, and the laser generates Stokes pulses of subnanosecond duration with a peak power of 1 megawatt.

Photoexcitation and photoluminescence spectra of b-Ga₂O₃ thin films obtained by high-frequency ion-plasmous sputtering in an argon atmosphere were investigated. Luminescence spectra were factorized on ultimate constituents using Alentsev-Fock method. The nature of the two intense bands with maxima at 2.95 and 3.14 eV, as well as two low-intensity bands with maxima at 3.90 and 4.25 eV was discussed. The intense bands were attributed to the associate originating due to the interaction of oxygen and gallium vacancies, low-intensity bands were associated with the recombination of excitons in quantum wells formed by the acceptor clusters. It was found that the damping time constant for the band with a maximum of 3.14 eV is 105 μs, and for the band with a maximum of 2.95 eV - 114 μs. The proximity of the decay time constants of these bands confirms their relationship with the common associate.

Method of fractal analysis was used to investigate the pattern of Rayleigh photoinduced light scattering (PILS) in a series of single crystals LiNbO₃: Zn (0.018-0.88 wt.%) that were grown from a congruent melt and are promising nonlinear optical materials with low values of the photorefraction effect and the coercive field. A comparative analysis of the results obtained by the method of fractal analysis and Raman spectroscopy was fulfilled. The extremes of the time dependence of the fractal dimension of the various layers of the PILS speckle structure were found, indicating changes in the concentration of the laser-induced defects in a photorefractive crystal. A non-linear dependence of the rate of change of the laser-induced defects concentration on the concentration of Zn in the crystal was found. Among the congruent lithium niobate crystals doped with zinc, the form with the most ordered structure was found.

The full complex of 18 fundamental optical functions of barium selenide crystal was obtained in the range 0-40 eV. Their main features and general laws were established. The calculations were performed using a series of computer programs based on the Kramers-Kronig integral relations, the Taft-Philippe extrapolation model and experimental reflectance spectra in regions 3.0-5.5 eV at 2 K and 3-40 eV at 77 K.

Arrays of ZnO nanostructures, which are optically transparent in the visible range, were grown on the surface of porous silicon by electrochemical deposition. Photoluminescence excitation and emission spectra of the obtained hybrid structures were investigated in 220-450 and 400-800 nm regions, respectively. It is established that multicolor emission is formed by combining the luminescence bands of porous silicon and zinc oxide. The possibility of the photoluminescence spectra controlling by changing the excitation energy is demonstrated. It is revealed that thermal annealing has an effect on the luminescent properties of porous silicon/zinc oxide hybrid structures. Thermal processing at 500^оС leads to the sharp decrease of long-wavelength luminescence associated with porous silicon and to the increase of short-wavelength luminescence intensity related to zinc oxide.

Cross-sections and efficiency factors of absorption, scattering, and attenuation of the laser radiation with a wavelength λ = 532 nm and in the wavelength range 475-625 nm for the two-layer spherical gold nanoparticles, which were partially melted, were calculated and studied theoretically for the particles with the radii r₀₀ = 10, 25, 50, 75 and 100 nm assuming different ratios between shell and core in the range 0-r₀₀. It was found that the changes in the optical parameters of nanoparticles with the changing of the aggregate state (melting) influences greatly on the heating dynamics of nanoparticles above the melting point and subsequent thermal processes.

Surface enhanced Raman spectroscopy (SERS) coupled with chemometric methods, such as adaptive iteratively reweighted penalized least squares (AIR-PLS), wavelet transform, and least squares support vector machine (LSSVM), was investigated to realize the rapid detection and identification of ractopamine (RAC) and clenbuterol hydrochloride (CL) residues in pork. First-level wavelet detail signal intensities at 1168 cm^{- 1} were used to establish a standard curve of the RAC residues in pork, and the linear regression equation and the correlation coefficient were y = -4.3683x - 11.059 and -0.9726. Second-level wavelet detail signal intensities at 1258 cm^-1 were used to establish a standard curve of the CL residues in pork, and the linear regression equation and the correlation coefficient were y=33.595x+36.538 and 0.9842. The second-level wavelet detail signals of the SERS spectra were selected as the inputs of the LSSVM classification model for the identification of the RAC and CL residues in pork, with a total accuracy rate reaching 100%. The experimental results demonstrate that the proposed method based on SERS is a good detection scheme for the rapid detection and identification of RAC and CL residues in pork.

The aim of this work is a multi-component analysis of the element composition of the enamel and carious parts of teeth and the quantification of enamel demineralization using laser-induced breakdown spectroscopy (LIBS). For each tooth the P/Ca ratios of the emission line intensities in the enamel part and those in the carious regions were compared. Since zinc is a trace element, the same procedure was performed for Zn/Ca ratios in the enamel and carious parts. These comparisons showed that the mineral loss from carious lesions occurs at different rates for the studied elements. Calcium has the highest casualty rate. On the other hand, the zinc level diminishes also in the carious region but at a lower rate. The lines were obtained from plume plasma emission generated on the enamel and carious regions.

The cholesterol gallstones studies by the electron paramagnetic resonance (EPR), X-ray diffraction (XRD) and nuclear magnetic resonance (¹Н ЯМР). The results indicated the identity of cholesterol gallstones spectra. In the bile stones, ESR method revealed the particles containing open spin-orbitals, which are the centers of colloidal particles. The spectra of¹Н ЯМР and XRD data indicate the presence of cholesterol and transition desmosterol in gallstones that form a shell around the spin centers.

It is shown that the effectiveness of phototherapy for hyperbilirubinemia of newborns using narrowband LED sources depends not only on the position of the LED emission spectrum peak within the absorption band of bilirubin but also on the width of the spectrum of incident radiation. It has been established that the extension of the spectral range of radiation by adding to the blue light band with l_max » 462 nm a green component with l_max » 505 nm (provided equal integrated power density) results in a more efficient decrease of the total bilirubin level in the blood of newborns. It is assumed that the effect is due to heterogeneity of spectral characteristics of bilirubin in a different microenvironment as well as to the dependence of the optimal wavelength for the pigment photoisomerization on the depth of location of blood vessels where reactions of the bilirubin phototransformation take place. Moreover, the extension of the spectral range of the incident radiation by addition of the green component increases irradiated volumes of blood where the photoisomerization reactions with a high quantum yield of lumirubin formation underlying the therapeutic effect of light upon treatment of hyperbilirubinemia are initiated.

Laser-induced breakdown spectroscopy (LIBS) has been applied to measure spectral characteristics and to perform quantitative analysis of the concentration of manganese in soil, an issue of great concern for precision agriculture. For the analysis, soil samples were compressed into pellets and a pulsed Nd:YAG laser was employed to produce the plasma in air at atmospheric pressure. Using this approach, we analyzed the time evolution of spectral characteristics and their dependence on the laser pulse energy. A calibration curve was constructed using reference sandy soil samples collected from a farm. An internal standard curve was used to improve the accuracy of the LIBS metrology for soil analyses. The results of this analysis demonstrated the usefulness of this method for analyzing the concentration of manganese in soil.

An apparatus for remote sensing and the results of spectroscopic measurements of atmospheric NO₂ content, carried out in the central part of St. Petersburg in 2009-2016, were presented. The method to determine NO₂ content was based on the spectral data of the visible solar radiation scattered from zenith. The obtained data are in qualitative agreement with the results of simultaneous similar measurements near St. Petersburg (Petrodvorets), as well as with the data of the nearby satellite measurements.

Signal characteristics of electronic absorption spectra of commercial and reservoir crude oil solutions have been determined including dispersion, expectancy, autocovariance and autocorrelation functions. Using oil samples from South Surgut and South Balyk it is found that these characteristics for the crude oils vary according to the oil properties, chemical composition and degree of preparation. Based on the obtained parameters, a method of identification for the oils studied is proposed.

We propose a novel algorithm for monitoring of dynamic objects by using integral optical flow. The algorithm is based on construction of field of integral optical flow and its structure allows one to describe stages of motion for dynamic objects. The algorithm allows one to analyze not only the motion of an object as a whole but also the internal structure of the object. Definition of stages of dynamic object development by integral optical flow allows one to make a detailed prognosis of evolution of such objects. Application of the proposed approach to three tasks: analysis of outdoor scene, cell image and flow monitoring. It allows one to improve the quality of solutions of many tasks for monitoring complex dynamic objects and can be applied into various automatic monitoring systems for complex motion investigation.

The interaction of coumarin-6 and eosin-Y with particles of protonated potassium polytitanate (PPT) has been studied by spectroscopic and luminescent methods. It is found that the anisotropy of fluorescence of coumarin-6 and eosin-Y in ethanol solution of potassium polytitanate is higher than in ethanol. This can be explained by the binding of the dyes with PPT particles. Based on obtained absorption spectra extinction coefficients for coumarin-6 (l=460 nm) e=25000 M^-1·cm^-1 and eosin-Y (l=525 nm) e=36,000 M^-1 · cm^-1 dyes were determined. It is shown that coumarin-6 and еosin-Y can be used to sensitize the PPT.

The transmission spectra of sol-gel derived strontium titanate films on quartz substrates have been studied in the optical range from 200 to 1100 nm. The sol is prepared on the basis of strontium acetate, titanium tetraisopropoxide, acetic acid, and ethylene glycol monomethyl ether. Strontium titanate films have been fabricated by successive deposition of five layers with intermediate drying of each layer and the final heat treatment in the temperature range from 500 to 750^oC. It is concluded from the analysis of the transmission spectra that the prepared films are characterized by the band gap value decreasing from 4.46 to 3.38 eV at the transformation from amorphous to crystalline films with a refractive index reaching 1.996 (at 620 nm) and high-density packaging up to 81.5% of that for monocrystalline strontium titanate.

The results of research Nd effect of impurities on the mechanism of photoconductivity and absorption of light in a single crystal GeS are present. The structure of the spectra investigated exciton states, the energy of direct and indirect band-to- band transitions has been determined.

The temperature coefficient of refractive index dn/dT is determined for glassy alloys of the As-S system along the As_хS_100-х direction (0 < х < 40) in the spectral interval of 1-5 µm at temperatures of 77-400 K. The glasses in question are shown to take negative, zero and positive values of dn/dT depending on the composition and wavelength. The dependence of the coefficient on spectrum and temperature is studied using a single oscillator model.

A thermoluminescence (TL) analysis was carried out to study the sensitivity and dose responses of Yb-Tb-doped SiO₂ optical fiber subjected to 1.25 MeV gamma radiation. The results are compared with the commercially available standard LiF:Mg,Ti (TLD-100) chip. The Yb-Tb-doped SiO₂ optical fiber and TLD-100 chips were placed inside Perspex and irradiated with 1.25 MeV gamma photons with doses ranging from 1.0 to 10.00 Gy. The results clearly show the superiority of TLD-100 chips in terms of response and sensitivity. The sensitivity of Yb-Tb-doped optical fiber and TLD-100 chips is 45.25 and 768.85 nc/(mg × Gy) respectively.

The structure, stability,¹⁴N NQR parameters, and hyperpolarizability of Fe(CO)₄py isomers in seven different solvents were computed with the MPW1PW91 method based on the polarizable continuum model (PCM). From an energetic standpoint, the Fe(CO)₄py_axial isomer was more stable than the Fe(CO)₄py_equatorial isomer. On the other hand, the relative energies decreased in more polar solvents. Molecular orbital analysis showed that the HOMO of the Fe(CO)₄py isomer was distributed on the Fe(CO)₄ fragment, whereas the LUMO was localized on the pyridine ligand. This study suggests that the nonlinear optical (NLO) properties depend on the solvent polarity.

Two new luminescent hybrid materials were synthesized using para-aminobenzoic acid (PABA), europium nitrate, and titania. Characterization of the synthesized hybrid materials using infrared spectroscopy and CHN elemental analysis revealed the bonding sites and compositions of the two hybrid materials. The homogenous nature of the hybrid materials was confirmed by scanning electron microscopy. The optical properties of these synthesized materials were studied using UV-visible absorption spectroscopy and photoluminescence spectroscopy. Thermogravimetric analysis revealed that the hybrid materials are thermally stable.

Heavy metal oxide (PbO and Bi₂O₃) glasses doped with transition metal (TM) ions (TiO₂, V₂O₅, Cr₂O₃, and MnO₂) and having low content of common glass formers (B₂O₃, SiO₂, or P₂O₅) were prepared by the conventional melt annealing method. Ultraviolet, visible absorption, and photoluminescence properties of these glasses were measured, and the data were employed to investigate the prepared glassy samples. The optical absorption spectra of TiO₂ and V₂O₅ exhibited three bands centered at about 240, 305, and 380 nm, followed by a broad asymmetrical near-visible band centered at 425-432 nm, while Cr₂O₃ and MnO₂ exhibited an extended visible peak at 517-548 nm. Results showed that the luminescence intensity changed with different transition metal oxides. From the absorption edge data, the values of the optical band gap E_opt and Urbach energy (∆E) were calculated. The calculated values of the optical energy gap were found to be dependent on the glass composition. The changing values of optical band gap and band tail can be related to the structural changes that are taking place in the glass samples. The variations of the luminescence intensity, values of optical band gap, band tail, and refractive index gave an indication of the potential use of the prepared glasses to design novel optical functional materials with higher optical performance.

The interactions between bovine serum albumin (BSA) and two Cu(II) phenanthroline complexes were studied by fluorescence and UV-visible absorption spectroscopy. The obtained results confirm that the phen ligand (phen = 1,10-phenanthroline) is dissociated from the two complexes and moves into the hydrophobic cavity of BSA and that the M-L complexes (M = Co²⁺ , Cu²⁺ ; L = Hlact, imda; Hlact = lactic acid, H₂imda = = iminodiacetic acid) coordinate with the amino acids on the surface of the peptide in the solution. This mode of action significantly inhibits the denaturation of BSA. The calculated distance between the BSA and the two complexes suggests that the energy transfer from the excited state of BSA to a complex occurs with high efficiency.

Flavanones are the main compound of licorice, and the C¢-4 position substitution is a significant structural feature for their biological activity. The ability of three selected flavanones (liquiritigenin, liquiritin, and liquiritin apioside) bearing different substituents (hydroxyl groups, glucose, and glucose-apiose sugar moiety) at the C¢-4 position and a chalcone (isoliquiritigenin, an isomer of liquiritigenin) to bind bovine serum albumin (BSA) was studied by multi-spectroscopic and molecular docking methods under physiological conditions. The binding mechanism of flavonoids to BSA can be explained by the formation of a flavonoids-BSA complex, and the binding affinity is the strongest for isoliquiritigenin, followed by liquiritin apioside, liquiritin, and liquiritigenin. The thermodynamic analysis and the molecular docking indicated that the interaction between flavonoids and BSA was dominated by the hydrophobic force and hydrogen bonds. The competitive experiments as well as the molecular docking results suggested the most possible binding site of licorice flavonoids on BSA at subdomain IIA. These results revealed that the basic skeleton structure and the substituents at the C¢-4 position of flavanones significantly affect the structure-affinity relationships of the licorice flavonoid binding to BSA.

Laser-induced breakdown spectroscopy (LIBS) is applied at natural atmosphere to compare the quantitative analysis performances of the toxic heavy metal element lead (Pb) in Pu’er tea leaves, determined by three calibration methods: the external standard method, the internal standard method, and the multiple linear regression method. The Pb I line at 405.78 nm is chosen as the analytical spectral line to perform the calibration. The linear correlation coefficients (R²) of the predicted concentrations versus the standard reference concentrations determined by the three methods are 0.97916, 0.98462, and 0.99647, respectively. The multiple linear regression method gives the best performance with respect to average relative errors (ARE = 2.69%), maximum relative errors (MRE = 4.94%), average relative standard deviations (ARSD = 9.69%) and maximum relative standard deviations (MRSD = 24.44%) of the predicted concentrations of Pb in eight samples, compared to the other two methods. It is shown that the multiple linear regression method is more accurate and stable in predicting concentrations of Pb in Pu’er tea leaf samples.

Transparent oxyfluoride germanosilicate glass-ceramics containing Er:PbF₂ nanocrystals is synthesized on the basis of SiO₂-GeO₂-PbO-PbF₂ initial glass doped with Er₂O₃. The glass-ceramics is characterized by yellow-green luminescence, the intensity of which is ~12-times higher than that for the initial glass. The redistribution of the intensity between green and red emission bands after the glass heat-treatment is explained using data of the lifetime measurements for six excited states of Er³⁺ ions from⁴I_{11/ 2} to²H_{11/ 2} . A substantial increase of the lifetime of the⁴F_{9/ 2} state (from 0.6 to 71 μs) is detected for the glass-ceramics as compared to the initial glass. UV up-conversion luminescence is observed for the glass-ceramics. The mechanisms of the up-conversion for 11 emission lines in the UV, blue, red, and deep-red spectral regions are discussed.