Rimary photochemical processes in molecules of polymethine dye probes 3,3 ¢ -di(g-sulfopropyl)-4,5,4 ¢ ,5 ¢ -dibenzo-9-ethylthiacarbocyanine betaine (DEC) and 3,3 ¢ ,9-trimethylthiacarbocyanine iodide ( Cyan 2) in the micellar systems of bile salts sodium cholate, sodium deoxycholate, and sodium taurocholate, as well as, for comparison, sodium dodecyl sulfate (SDS), have been studied by flash photolysis. Upon flash photolysis of aerated aqueous solutions of the dyes in the presence of micelles of bile salts and SDS, signals due to photoisomerization of the trans-isomers of the dyes and back dark isomerization of cis-photoisomers formed are observed. The lifetimes of the photoisomers are in the range of 60-190 μs. Moreover, upon flash photolysis of deoxygenated solutions of Cyan 2 and DEC in the presence of micelles of bile salts and SDS, in addition to photoisomerization, the transition of the dyes to the excited triplet state and the subsequent backward transition (intersystem crossing) to the initial singlet state occur. For comparison, the triplet-triplet absorption spectra of the isomers of the dyes have been obtained by the method of triplet-triplet energy transfer from anthracene in polar (ethanol, isopropanol) and nonpolar (dioxane) solvents. A conclusion is drawn about the similar photochemical behavior of the dyes in the micellar systems of bile salts and SDS.

Spectral luminescent properties of an indotricarbocyanine dye are studied in solution and after deposition onto quartz or silicon substrates. It is found that the molecules of the dye are self-assembled in aqueous ethanolic solutions, forming H*-aggregates. Absorption band of the H^*-aggregates shows a hypsochromic shift of 192 nm (5291 cm^-1) with respect to the monomer absorption peak (706 nm) and has the full width at half maximum of 21 nm (797 cm^-1). The morphology of the H^*-aggregates is studied for the first time. It is found that the H^*-aggregates of the indotricarbocyanine dye constitute rod-like objects that are about 10 nm high, 100 nm wide, and several micrometers long. In addition to non-fluorescent H^*-aggregates, H-aggregates are formed in aqueous ethanolic solutions of the dye. These H-aggregates possess fluorescence peak at 560 nm with a Stokes shift of 325 cm^-1 and constitute nanoparticles with a height of 1-3 nm and the lateral dimensions of about 100 nm.

A model of the formation of rotationally nonequilibrium ensembles of molecular complexes in the gas phase is developed taking into account the vector dynamics of translational-rotational exchange and its manifestation in the anisotropy of light absorption and emission. On the basis of the proposed model, the optical anisotropy of the ensemble of molecular complexes is calculated depending on the magnitude of the change in partial angular moments and the ratio of the moments of inertia of the initial fragments and the resulting complexes. It is shown that the increase in the value of the additional angular momentum, due to the moments induced during the rotational-translational exchange, can cause both a decrease in anisotropy and its increase depending on the shape of the ellipsoids of inertia of the complexes.

Spectral-luminescent characteristics of a mixture of coumarin 7+rhodamine B dyes infiltrated into a one-dimensional photonic crystal based on mesoporous silicon are investigated. The electron excitation energy transfer between molecules, accompanied by the quenching of the donor fluorescence (сoumarin 7) and the enhancement of the acceptor emission (rhodamine B) is detected. The angular dependence of the excitation energy transfer efficiency in the donor-acceptor pair is established; it is due to the depletion of available photon modes for the radiative decay of the donor in a photonic crystal in comparison with the homogeneous medium and depends on the spectral position of the photonic stop zone of a photonic crystal.

The effect of collisions for which the particle velocity is changed on the intensity of the stimulated photon echo response in a gaseous medium is investigated. It is shown that such collisions have the greatest influence on the intensity for the non-parallel wave vectors of exciting pulses. An approximate dependence of the intensity of the response of the stimulated photon echo on the time interval between the second and third exciting laser pulses is proposed. This dependence permits to differentiate the contribution of collisions with the change of the velocity of particles to the attenuation of the response. It is of interest for optical coherent echo spectroscopy.

The vibrational spectra of b-LiNH₄SO₄crystals in the ferroelectric phase (space group No. 33) are studied. On the basis of group-theoretical analysis, a classification of the vibrational symmetry is performed. Using the first-principle approach within the framework of the electron density functional theory, as well as the perturbation theory, the vibrational frequencies of the structural elements of the crystal are calculated. The Raman scattering spectra of the b-LiNH₄SO₄ crystal are calculated and compared with the experimental literature data. Based on the theoretical calculations, the main structural components playing one of the major roles for optical studies are discussed.

Near-infrared diffuse reflectance spectroscopy is proposed for the classification of pathogenic bacteria using optical properties. The spectrally resolved data are analyzed using a diffuse reflectance model to extract the local optical properties, including the reduced scattering coefficient and absorption coefficient. The optical properties at different wavelengths form the feature set. A particle swarm optimization-based support vector machine is used to classify seven categories of bacteria. The experimental results demonstrate the feasibility of the method for the rapid and noninvasive classification of pathogenic bacteria using optical properties.

The analysis of¹³C-satellites was carried out in the¹³C NMR spectra of isoprene rubbers with the natural content of¹³C carbon isotope.¹³C-satellites are the signals caused by the one-bond spin-spin coupling of¹³C nuclei. The spin-spin coupling¹J(¹³C-¹³C) constants, as well as the magnitude of the effect of the isotopic substitution¹∆δ¹³C(^13/12C), were measured under magnetic shielding of¹³C nuclei. The results indicate the identity of the configurational and local conformational structure of natural and synthetic isoprene rubbers.

This study focuses on the feasibility of nondestructive discrimination of high-quality watermelon seeds with a multispectral imaging system combined with chemometrics. Principal component analysis (PCA), least squares-support vector machines (LS-SVM), back propagation neural network (BPNN), and random forest (RF) were applied to determine the seed quality. The results demonstrate that both the spectral and the morphological features are essential for discrimination of the quality of watermelon seeds. Clear differences between high-quality watermelon seeds and other watermelon seeds including dead seeds and low-vigor seeds were visualized, and an excellent classification (with accuracies of 92% in the LS-SVM model for Julong and 91% in the RF model for Xiali, respectively) was achieved. These results indicate that multispectral imaging could be used for rapid and efficient non-destructive quality control of watermelon seeds.

This study aims to determine the urinary stones’ chemical compositions, morphologies and crystal size by using X-ray diffraction, scanning electron microscopy with energy dispersive X-ray, and Fourier transform infrared spectroscopy. This study has been conducted with 30 urinary stones from the 30 patients who were treated at the Department of Urology in Mersin University Hospital (Mersin, Turkey). With respect to the detected phase compositions, results were classified into four chemical groups: oxalates (43.3%), phosphates (13.3%), urates (6.7%), and mixed stone (36.7%).

Dynamic spectrum theory has great importance in the field of noninvasive measurement of blood components. To enhance the computational efficiency and data utilization of the existing extraction methods, this paper proposes a new one based on the absolute difference summation (ADS) and statistical theory. The ADS is used to obtain the eigenvalue from a photoplethysmography (PPG) signal. The statistical method is used to obtain the final dynamic spectrum. The experimental data of PPG signal from 133 volunteers were extracted by the new method and the single-trial (ST) extraction method, and the partial least squares model was used to build the calibration models. Compared with the ST extraction, the new method showed better prediction ability. The correlation coefficient of the prediction set increased from 0.85 to 0.92, and the root mean square error of the prediction decreased from 13.49 to 9.86 g/L, which proved that this method can significantly improve the quality of the dynamic spectrum.

Some bio-effective constituents, such as organic acids and phthalides, from the root of Angelica sinensis can be observed in the blood after oral intake. In this work, two organic acids, ferulic acid and anisic acid, and two phthalides, senkyunolide I and butylidenephthalide, were selected to investigate the interaction with bovine serum albumin systematically, using a fluorescence spectroscopic method under physiological conditions. The Stern-Volmer quenching constant, binding constant, and the corresponding thermodynamic parameters and binding numbers were measured. Synchronous fluorescence and three-dimensional fluorescence spectroscopy were also used. The results provided molecular spectroscopy evidence that some constituents of Angelica sinensis are absorbed and transported into the blood.

The stability of micellar solutions of amiodarone hydrochloride in the presence of polysorbate-80 and benzyl alcohol at l_ex = 420 nm and l_em = 506 nm was studied by spectrofluorimetry. A scheme of the formation of mixed micelles consisting of nonionic surfactant polysorbate-80 molecules and cationic molecules of amiodarone with chloride ions as counter-ions is proposed. It is established that the presence of benzyl alcohol reduces the stability of mixed micelles and leads to the crystallization of amiodarone hydrochloride. It was shown that in the presence of acetate ions, substitution of counter-ions occurs and, as a result, the formation of crystals of amiodarone acetate takes place, which has the characteristic band of valence vibrations of the acetate carbonyl group ν_С=О at 1734 cm^-1 in the IR spectrum. The solubility values of amiodarone hydrochloride and amiodarone acetate in water at 20°C were determined to be 0.33 and 0.058 mg/mL. It is recommended to change the molar ratio of amiodarone hydrochloride and polysorbate-80 and also not to use benzyl alcohol and acetate-containing solutions to improve the stability of the injectable drug.

He principal possibility of the lung and breast cancer diagnosis by studying of saliva with the use of the method of infrared Fourier spectroscopy is shown. Statistically significant differences in the saliva IR spectra of patients with lung cancer are observed in the range of 1070-1240 cm^{- 1} , whereas for patients with breast cancer - they are observed in the whole studied spectral range. The coefficients I_{1398/ 1454} and I_{1240/ 1310} were revealed, the change of which on the background of oncological pathology are statistically significant. The intensity correlations of the saliva absorption bands in the IR spectra with non-specific biochemical parameters, which in general form characterize the enhancement of intoxication, inhibition of the antioxidant defense system and the immune response of the organism, were established. A promising area of research is the use of saliva IR spectroscopy to monitor the treatment process and control the occurrence of cancer recurrence.

A technique is proposed for the selection of optimal parameters for solving the inverse problem of determining the total content (TC) of freons by ground-based spectrometric measurements of solar radiation. The technique is designed for measurements at the NDACC station “St. Petersburg” using a Fourier interferometer Bruker FS125HR. The proposed technique is implemented with reference to measurements of the total content of hydrochlorofluorocarbon R-22 (HCF2Cl). Based on the obtained optimal set of parameters, the retrieval of the R-22 TC over the St. Petersburg station was performed in the period 2009-2018. Estimates of measurement errors are obtained: the average systematic error is 4.8%, a random 3.7% for the entire observation period. Preliminary assessment of the trend was 2.64 ± 0.22% per year.

A new synchronous fluorimetric method for the analysis of bisphenol A has been developed based on procaine hydrochloride as a self-quenching fluorescence probe. In acidic solution, procaine hydrochloride could be diazotized with sodium nitrite; then the diazotized product could react with bisphenol A in NH₃-NH₄Cl buffer and produce the quenching of fluorescence of diazotized procaine hydrochloride-NH₃-NH₄Cl solution. Based on this observation, an inhibitory fluorimetric method is reported for the determination of trace bisphenol A. The synchronous spectral peaks of the reaction system are at 225 and 270 nm. The spectra of the two peaks can be separated, and bisphenol A can be determined directly. The possible mechanism of the reaction has also been discussed. Under optional conditions, bisphenol A can be determined over the concentration range of 0.10 to 1.4 μg/mL with a correlation coefficient of 0.99. The detection limit is 0.04 μg/mL at a signal-to-noise ratio of 3. The relative standard deviation (RSD) for 11 repetitive determinations of 1.0 μg/mL bisphenol A is 0.32%. The utility of this method was demonstrated by determining bisphenol A in hot water in contact with commercially available table-water bottle samples.

The application of synchronous fluorescence spectroscopy combined with chemometrics using pretreated spectra was explored to develop a rapid, low-cost, and nondestructive method for discriminating between brands of different strong aroma type liquors. Principal component analysis, partial least square discriminant analysis, support vector machine, and back-propagation artificial neural network techniques were used to classify and predict the brands of liquor samples. Compared with the other models, the SVM model achieved the best results, with an identification rate of 100% for the calibration set, and 96.67% for the prediction set. The overall results showed that synchronous fluorescence spectroscopy with an efficient chemometrics method can be used successfully to identify different brands of liquor.

Reaction of spontaneous oxidation of an adrenaline in an alkaline condition is investigated by method of an electronic spectroscopy. Influence of pH of on the provision of maxima in an adrenaline absorption spectrum is shown. The analysis of absorption spectra of the reactionary environment during process of oxidation revealed dynamics of change of an optical density of the formed products. The method of a quantum chemistry within the theory of a functional of density received theoretical ranges of an adrenaline, an adrenolutine and an adrenoсhrome. The technique of the quantitative analysis of products of spontaneous oxidation of an adrenaline is developed.

At the Siberian Lidar Station of V.E. Zuev Institute of Atmospheric Optics SB RAS in Tomsk (56.5° N., 85.0° W), a lidar system is created to study the ozone dynamics in the tropopause region and to monitor the global changes in ozonosphere by measuring the vertical ozone distribution in the upper troposphere-stratosphere. Based on the method of differential absorption and taking into account the temperature and aerosol corrections, sensing is performed at wavelength pairs 299/341 and 308/353 nm. The lidar system coves the altitude range of ~5-45 km.

Suspensions of single- and double-walled carbon nanotubes of various lengths, as well as multi-walled carbon nanotubes, have been studied by Raman spectroscopy in combination with confocal microscopy. It is shown that the intensity of the G mode in the Raman spectra of the carbon nanotubes is directly proportional to the nanotube concentration, the exposure time, the power and focusing depth of the exciting radiation in the transparent sample under study. It is found that the Raman spectra of longer carbon nanotubes (~1 μm) are characterized by a higher intensity of the G mode compared with the short nanotubes (~250-450 nm). The dependences obtained have been used to determine the local intracellular concentration of the carbon nanotubes within the waist of the exciting laser beam in order to create a map of the distribution of the carbon nanotubes inside the cells.

A very simple by logic and convenient to program mathematical model for describing and investigating by computer simulation the optical spectra of polyatomic molecules in the range from IR to UV including the region of Rydberg states is proposed. For a given geometry of the molecule, only the elements of the force constant matrices for the ground and electronically excited states, as well as the depth of the wells are the variable parameters. Functions for electrons are given by sets of principal quantum numbers for the radial components in a hydrogen-like atom. The model allows solving both direct and inverse problems.

The thin films (~100 nm) of complex compounds of terbium(III) with 2-benzoylbenzoic, 2-(4-chlorobenzoyl)-benzoic and 3,4-diethoxybenzoic acids have been obtained. Using the data of electron and optical microscopy, it is found that the complex crystallizes during the film formation. In order to improve the surface quality of the films, the complexes have been doped into a poly-(N-vinylcarbazole) polymer matrix in ratios from 1:1 to 10:1. Based on the dependence of the luminescence integral intensity of the films on the mass ratio of the components, a participation of the polymer in the luminescence excitation of the complexes in the film is supposed.

The Sm³⁺ doped Sr₃B₂O₆ phosphors were synthesized using a solution combustion synthesis method followed by heating of the precursor combustion ash at 1000ºC in air. The synthesized phosphors were characterized by powder XRD. The photoluminescence properties of Sm³⁺ doped Sr₃B₂O₆ were investigated at room temperature. The photoluminescence spectra at room temperature show the f-f transitions typical for Sm³⁺ . The emission spectrum of Sr₃B₂O₆:Sm³⁺ exhibited four sharp emission peaks corresponding to⁴G_5/2®⁶H_{5/ 2} (563-572 nm),⁴G_5/2®⁶H_{7/ 2} (598-614 nm),⁴G_{5/ 2} ®⁶H_9/2 (647-666 nm), and⁴G_{5/ 2} ®⁶H_{11/ 2} (705 - 714 nm) transitions of Sm³⁺ . The relation between the charge transfer band of Sm³⁺ ion and the host composition was discussed.

The enhancement of UV luminescence and random lasing of disordered arrays of ZnO nanorods with Ag coating has been found in the magnetic field of about 1 T at room temperature. A possible interpretation of the effect is suggested based on the assumption of the formation of magnetoexcitons in ZnO under the magnetic field action in the presence of surface plasmon resonance.

The terahertz spectra of salicylic acid and sodium salicylate are measured by broadband terahertz time-domain spectroscopy (THz-TDS). Two absorption features of salicylic acid and three characteristic features of sodium salicylate are reported for the first time. Our investigation shows that salicylic acid and sodium salicylate can be easily distinguished based on their distinctive THz spectra, which could be attributed to their intra- and intermolecular structure differences. Furthermore, solid-state density functional theory calculations reveal that the absorption features of salicylic acid mainly originate from intermolecular interactions, except the absorption feature at 2.28 THz, while gaseous-state theory calculations show that the absorption features of sodium salicylate mainly come from intramolecular vibrations except the absorption feature at 0.40 THz. Our investigation indicates that THz vibrational modes are highly sensitive to molecular structures and intermolecular interactions, promoting the application of THz spectroscopy in distinguishing chemicals and pharmaceuticals with similar molecular structures.

This study focuses on the determination of drugs, namely nimesulide, amoxicillin, and tribulus terrestris, in an alkaline medium as well as in blood samples, urine, and commercial tablets. The study examines such factors as reproducibility, repeatability, robustness, and accuracy in the determination of the drugs in the samples.