The problems of application of quantum-cascade lasers (QCLs) in biomedical practice are considered. A comparative analysis of laser spectroscopy methods for non-invasive diagnostics of diseases by exhaled air has been carried out; examples of the practical implementation of this idea based on QCL are given. The use of QCL in traditional laser surgery and laser angioplasty is discussed. Particular attention is paid to the consideration of terahertz imaging of soft tissues, as well as to the issues of microspectroscopy and the creation with its help of hyperspectral images of biological tissue in the middle infrared range. A number of problems associated with the use of QCL in medicine have been formulated, and possible directions for promising research, where QCL can play a decisive role, are indicated.

The following radiative parameters are calculated: Einstein coefficients of spontaneous radiation, oscillator strengths for absorption, Frank-Condon factors, wavenumbers of electronic-vibrational transitions in the electronic bands (2)²S ⁺ -Х ²S ⁺ of molecular ions NaK⁺ (0 £ v′ £ 14, 0 £ v′′ £ 100), NaCs⁺ (0 £ v′ £ 14, 0 £ v′′ £ 69), and also radiative lifetimes of the excited electronic states. Calculations are carried out with the use of Hulburt-Hirschfelder potential curves for the basic and excited electronic states constructed by means of the literature ab initio calculation data. The vibrational energies and the wave functions necessary for the calculation of the radiative parameters are found as a result of numerically solving the Schrödinger equation.

The absorption and fluorescence spectra of positively and negatively solvatochromic merocyanine dyes with the same structural type in polymer films of different polarities (polystyrene, polyvinyl butyral, and poly-N-epoxypropylcarbazole) are studied. It is found that negatively solvatochromic merocyanines are more prone to aggregation than positively solvatochromic dyes. Based on the quantum chemical DFT calculations, this is explained by the larger dipole moments of the former. It is shown that merocyanine aggregates have a sandwich-type structure, which results in the fluorescence quenching. It is found that in more polar polymers the aggregation occurs at higher dyes concentrations. It is established that, as in liquid solutions, the studied merocyanines have noticeable solvatochromism in polymer films. Although the fluorescence intensity of merocyanines increases in going from liquid solutions to polymer matrices, the most important factor determining their fluorescence ability in polymers is the polyene-polymethine transformations in their molecules.

In engine oil, the element composition and concentration changes as the engine operates. A rapid and effective detection of these changes, therefore, is needed to prevent accidents. Indirect ablation laser-induced breakdown spectroscopy (IA-LIBS) is a new technology introduced specially for oil samples. In this paper, 5 different oils are used for the analysis. The matrix effect on the calibration curves of analytical elements (Cu, Ti, Fe, and Ni) in these oils is investigated. The results show that the matrix effect is reasonably negligible under the conditions of our experiment. A generalized calibration curve can be established for analytical metals in different types of oils. We use the generalized calibration curves established to determine the concentrations of Cu, Ti, Fe, and Ni in mixed oils. The IA-LIBS results show that good agreement is obtained between the measured and known values.

The formation features of the regime of single-frequency unidirectional monopulse lasing of Nd:YAG laser with a triple-mirror ring cavity and a side diode-pump under the condition of injection of external narrow-band optical radiation into the resonator are studied. It is experimentally shown that the asymmetrical layout of the intracavity elements relative to the laser output mirror and the depolarization effects in these elements lead to a difference in the energy and polarization of the monopulse Nd:YAG ring laser depending on the direction (clockwise or anticlockwise) of the input of the injected radiation. The difference in the output characteristics of the single-frequency unidirectional monopulse Nd:YAG ring laser is the most evident in the case of transition from the active to the passive Q-switching.

The IR Fourier reflectance spectra (50-500 cm^{- 1} ) of ZnS ceramics synthesized by the chemical vapor deposition (including those with an additional hot isostatic pressing), hot pressing, and physical vapor deposition are presented. The phase composition of raw materials and the temperature prehistory of the samples assumed their cubic crystallographic structure (sphalerite). However, a weak band at ~295 cm^{- 1} , which is characteristic of the hexagonal phase in ZnS crystals (wurtzite) manifested itself both in the reflectance spectra and in the spectra of optical constants of all samples. The recrystallization sphalerite ® wurtzite below the nominal phase transition temperature (1023 ºС) may be a consequence of the tendency of the ZnS compound to the polytypical structure formation, which is facilitated in this ceramic material by the high heterogeneity of the structure of the crystallites themselves.

It is shown that changes in the concentrations of usual radiation defects and formation of near-cluster radiation defects (color centers) occur in nanocrystals fabricated by mechanical fragmentation of irradiated LiF crystals. Concentrations of near-cluster color centers increase to a stationary value after fragmentation and remain constant at room temperature for a long time. It has been established that influence of UV radiation on fabricated nanocrystals after termination of center formation processes in them significantly increases the concentration of near-cluster defects containing three anion vacancies and two electrons. It is demonstrated that there are single-vacant color centers as well as usual and near-cluster aggregate color centers in unirradiated nanocrystals fabricated by fragmentation of unirradiated crystals.

The aim of this work is to establish the correlation between differential scanning calorimetry and Raman spectroscopy in the determination of the mechanical properties of TiO₂/epoxy resin nanocomposites. Commercial RTM6 epoxy resin with TiO₂ nanoparticles of 21 nm in diameter is used. Magnetic stirring for 5, 30, and 60 min is employed for the preparation of this epoxy. The rate of the reticulation of epoxy is reinforced by different percentages of TiO₂ nanoparticles and is strongly affected by the cure temperature. The results indicate that the 1255 cm^{- 1} peak intensity, corresponding to the C-C stretch, decreases during the cure leading to the variation of the mechanical properties (hardness) of the nanocomposites.

The Raman scattering enhancement is shown using Au/SiGe and Au/Ge substrates obtained by the method of chemical deposition of SiGe and Ge layers from the gaseous phase under reduced pressure on silicon substrates and thermal deposition of gold. AFM image analysis shows the cone-shaped nanorods formed on the surface of the substrates. These nanostructures permit to obtain the enhancement of Raman scattering of mitoxantrone (C = 10^{- 5} M) up to 2-3 orders as a minimum. Using the 785 nm excitation wavelength, an additional enhancement of the SERS signal in 1.7-4.3 times for the Au/Ge substrates and in 1.5-5.5 times for the Au/SiGe substrates is observed.

A new simple classification modeling procedure, multi-wavelength statistical discriminant analysis (MW-SDA), is proposed for the identification of Shandong green tea origins coupled with near-infrared (NIR) spectroscopy. After smoothing and first derivative preprocessing, seven characteristic wavelengths (CW) were selected by enlarging the detailed information of preprocessed spectra. Then, for each characteristic wavelength, a classification threshold is calculated according to the differences in absorbance value, which can best separate the spectra for different origins. Based on the seven CWs and corresponding thresholds, seven classifiers were obtained, which form the classification model. The performance of the calibration model was evaluated according to sensitivity, specificity, and classification accuracy. Analysis results indicated that MW-SDA can be used well to build classification models. The predicted precision of the last model in prediction set was: sensitivity = 1, specificity = 0.967, and accuracy = 98.3%.

He samples of needles of spruce European Picea abies and Scots pine Pinus sylvestris L. collected in Tver in zones with different anthropogenic load were investigated. The chemical composition of conifer needles of different years of life was determined. The infrared absorption spectra and UV spectra were used to compare the accumulation of pollutants in the needles of different species of coniferous trees at collection points with a similar anthropogenic load. The dependence of the qualitative chemical composition of the needles was determined in accordance with the type of polluting factor depending on the collection point.

Core-shell magnetic metal organic nanocrystals were synthesized and used as matrix for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Four nitropolycyclic aromatic hydrocarbons (nitro-PAHs) were successfully detected by using negative-ion MALDI-TOF MS without background interference. Furthermore, the magnetic nanocomposites (MNCs) coated with zeolitic imidazolate framework-8 (ZIF-8) showed excellent adsorption and enrichment capacity, and can be isolated with a magnet and directly spotted on the stainless steel plate for MALDI measurement. It was also analyzed nitro-PAHs in PM2.5 samples using the ZIF-8-coated magnetic nanocomposite as adsorbent and matrix.

The current study aims at discriminating cotton and woolen textile fibers from dye using UV-Vis spectroscopy and chemometrics methods. For extraction of the dye from fibers, seven solvent systems have been used, and different extraction conditions have also been tested. Two different approaches, i.e., a visual comparison of peaks and chemometric analysis, have been proposed to differentiate between the textile fibers. The comparison of peaks obtained through UV-Vis spectra provides the discrimination power of 83.6% for cotton fibers and 94.3% for the woolen fibers. However, the incorporation of chemometrics has further improved the discrimination power to 100% for cotton and 98.1% for woolen fibers. The discrimination of 100% is achieved with nonsignificant values of the Welch’s t-test, which illustrates that all samples are discriminated.

Fast methods for reducing the dimensionality of spectral data are developed. In contrast to the widely known methods of projecting data with a N dimension into spaces of a smaller dimension having a computational complexity of N´N order proportional to the dimension of the covariance data matrices, it is proposed to use new methods to reduce the complexity. They are feasible in a sliding window in n of counts. As a result, fast methods have the computational complexity of n´N order. The results of computer experiments of reducing the dimensionality of the IR spectra of automobile gasolines are represented. The problem of reducing the dimension of IR spectra is topical for their visualization as well as for decreasing the multicollinearity and the influence of noise while modeling the behavior or analysis of parameters depending on the spectral characteristics.

The possibility of determining a grain corps having a different grinding by the diffuse reflection spectrum was experimentally confirmed. Combinations of optical densities and their second derivatives for the wavelengths of 1200, 1422, 1778, 1916, and 2114 nm were used as features describing the diffuse reflection spectra of wheat and oats of different milling and humidity in the near infrared range. Using the example of logistic regression, 20 classification models based on two features were constructed: 10 models for optical density and 10 models for the second derivative of the optical density corresponding to the selected wavelengths. The best classification results were obtained by an algorithm that used the values of the second derivative of optical density at 1778 and 2114 nm as features.

The electrodynamic model of a fiber-optic hydrogen sensor is proposed, in which a taper with a nanoscale palladium coating, created in a photonic crystal fiber, is used as the sensing element. Based on the model, experimental data have been processed for transmission spectra of the taper with the palladium coating of 8 nm thick at various hydrogen concentrations in a nitrogen atmosphere. It is established that an increase of the hydrogen concentration leads to a growth of integral transmittance of the sensor and practically does not affect a wavelength position of the transmittance interference maxima. The possibilities for optimizing the sensor by choosing a length of the taper waist are determined.

The correction is proposed allowing to refine the surface temperature determined by a standard non-invasive thermographic method based on IR images for the human skin with a non-uniform in depth temperature distribution. The non-uniformity is due to the biophysical necessity of normal functioning of the organism, as well as to a possible presence of pathological processes in certain areas of the body. The measured brightness can be spectral or polychromatic one. The value of the correction is analyzed depending on the size, shape and thermal power of the pathological source, as well as on the depth of its location, thermophysical and optical characteristics of the biological environment.

EPR of Mn²⁺ ions in three cubic nano-ZnS samples was studied. The samples were obtained by different technological processes and the sized of nanoparticles were different. Manganese was in the samples as an uncontrolled impurity. The EPR spectra of all samples can be described by two components - the spectrum of Mn²⁺ in the cubic surrounding, Mn²⁺ (C), with the parameters g = 2.0022 ± 0.0002,A = (-63.5 ± 0.5)´10^-4 cm^-1 , b₄⁰ ³ 3.5´10^{- 4} cm^{- 1} and the spectrum of Mn²⁺ ion associated with planar lattice defect of the packaging, Mn²⁺ (D). The parameters of Mn²⁺ (D) spectrum are: g = 2.0022±0.0002, A = (-63.5±0.5)´10^{- 4} cm^{- 1} , b₂⁰ = = (-36±1)´10^{- 4} cm^{- 1} . The ratio of centers amount Mn²⁺ (C)/Mn²⁺ (D) for the samples studied was 2.1:1 (sample 1) and 1.7:1 (samples 2 and 3). Planar packing defects are typical lattice defects in cubic nano-ZnS. EPR of Mn²⁺ allows one to monitor the presence of these defects.

The results of studies by the method of spectral ellipsometry of a surface of silicon implanted with oxygen ions in the dose range of 7.5×10¹⁴-3.7×10¹⁶ ion/cm² and helium ions in a dose range of 6×10¹⁶-6×10¹⁷ ion/cm² with an energy of 40 keV at constant ion current density 2 μA/cm² and room temperature of the irradiated substrates are presented. Dependences of the thickness of the implanted layer in irradiated plates and the degree of its amorphization on the dose of ion implantation are obtained.

The structural, geometric, spectroscopic, and electronic properties of the 1-(benzyloxy)urea (C₈H₁₀N₂O₂) molecule were investigated using experimental and computational methods. The experimental studies were performed via FT-IR, Raman, and NMR spectroscopies for the determination of vibrational and magnetic properties of the title compound. The molecular geometry optimization, vibrational wavenumbers, proton and¹³C NMR chemical shifts (in DMSO), HOMO-LUMO analyses, and UV-Vis spectral parameters (in DMSO) for the title molecule were computed with the DFT/B3LYP method at the 6-311++G(2d,2p) basis set. The assignments of harmonic vibrational wavenumbers were computed using the VEDA 4 software program in terms of potential energy distribution (PED). The HOMO-LUMO and UV-Vis analyses were used to determine intramolecular charge transfer and electronic transitions in the title molecule. The experimental values of vibrational frequencies and NMR chemical shifts are in a good harmony with the computed values.

The spectroscopic and ro-vibrational constants, FCFs and r-centroids have been evaluated in the present study for A²Π_1/2-X²Σ, A²Π_3/2-X²Σ, B²Σ-X²Σ, E²Π_1/2-X²Σ, E²Π_3/2-X²Σ, F²Σ-X²Σ, and L²Π-X²Σ band systems of the barium deuteride (BaD) molecule by adopting a reliable numerical integration procedure. The physical and astrophysical significances of the evaluated FCFs and r-centroids are discussed for all these band systems. The effect of vibration rotation interaction (VRI) on FCFs for the bands of the chosen band systems of BaD molecule is also studied. It is found from the results that the effect of VRI on FCFs is not so significant for the rotational quantum number (J) up to J = 50. For higher values of J like J = 100, there is a slight change in the value of FCFs due to the VRI effect.

The interaction between quercetin and taxifolin with β-lactoglobulin (BLG) was investigated via various methods, including fluorescence spectroscopy, molecular docking and molecular dynamics (MD) simulation. The results have demonstrated that quercetin binds BLG with an affinity higher than that of taxifolin, which is attributed to the nonplanar C-ring and steric hindrance effect in taxifolin. The synchronous fluorescence spectra shows that quercetin and taxifolin do not induce conformational changes of BLG. Molecular docking studies have demonstrated that several amino acids are involved in stabilizing the interaction. Analysis of the MD simulation trajectories shows that the root mean square deviation (RMSD) of various systems reaches equilibrium. Time evolution of the radius of gyration shows as well that BLG and BLG-flavonoid complexes are stable within 5 ns. In addition, analyzing the RMS fluctuations, one can suggest that the structure of the ligand binding site remains rigid during the simulation. The secondary structure of BLG is preserved upon interaction with these flavonoids.

Analysis of carbon (C) in soil has been successfully made by laser plasma spectroscopy using a pulsed carbon dioxide (CO₂) laser. Fine particles of soil sample were attached on a surface of the metal subtarget by adding a small amount of moisture; the metal was used to initiate the gas plasma. Experimentally, a pulsed laser was focused on the subtarget to induce a luminous plasma. The particles were vaporized and entered the plasma region. Dissociation and excitation happened in the high-temperature plasma region. The result certified that analysis of C in soil can be demonstrated. A further measurement revealed that a calibration curve of C was successfully carried out. The limit of detection of C in the soil was around 23 mg/kg.

Among several techniques used to study pesticides, Raman spectroscopy stands out for providing fast and reliable results. The objective of this work is to construct a database with Raman spectra of the main commercial pesticides currently used and make it available to the scientific community. With this aim, liquid and solid samples from 78 pesticides were collected. For the Raman spectroscopy analysis of pesticides, a portable Delta Nu Raman spectrometer with a 785 nm laser wavelength and 8 cm^-1 resolution was used. The results obtained from the different pesticides were grouped into tables showing the action class, chemical class, active ingredient, and relative intensities of the characteristic Raman bands.

This work represents a contribution to the analytical spectrophotometric methods applied to resolve the spectral overlapping of cinchocaine hydrochloride (CIN) and betamethasone valerate (BMV), for the sake of their simultaneous determination in the presence of their hydrolytic degradation products and in the pharmaceutical formulation, with no need for preliminary separation. Conventionally assisted mathematical univariate techniques, including the use of the isoabsorptive point, dual wavelength, ratio subtraction, first derivative of the ratio spectra and ratio difference, are applied; these methods are able to determine the two drugs simultaneously in binary mixtures but not in the presence of their degradation products. For the determination of CIN, a direct measurement of its zero order absorption spectra at 327.0 nm is performed, where BMV showed zero absorbance. Betamethasone valerate is determined by the developed univariate methods after resolving the CIN spectral overlapping. For the determination of both CIN and BMV in the presence of their degradation products, two multivariate calibration methods are proposed using principal component regression and partial least squares. The developed methods are validated as per the ICH guidelines and can be applied for routine quality control analysis.