JournalTOCs

Optics and Spectroscopy
Journal Prestige (SJR): 0.319

Citation Impact (citeScore): 1
Number of Followers: 8

Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1562-6911 - ISSN (Online) 0030-400X
Published by Springer-Verlag

[2467 journals]

Ignition of Al- and B-Based Dispersed Fuels by a Radiant Heat Flux
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  Abstract: Ignition of Al conglomerate particles and Al-, B-, and AlBn-based dispersed fuels under radiant heating by a cw CO2 laser with heat flux densities q = 65–190 W/cm2 is experimentally studied. Based on the results obtained, the dependences of the ignition delay time on the heat flux density are determined and a mechanism of ignition of an individual Al particle and dispersed metal fuels in air is described. It is found that the ignition delay times of aluminum bromide micropowders are shorter than those of Al powder by 1.9‒2.3 (AlB2) and 3.2–3.5 (AlB12) times under the same heating conditions. The ignition delay times of amorphous boron are minimal (3–10 times shorter than that of Al). The ignition temperatures of AlB2 and AlB12 powders are 110–130°C higher than the ignition temperature of aluminum micropowder. With increasing mass concentration of boron in AlB12 particles, the heat release rate upon powder heating and oxidation increases.
  PubDate: 2022-12-09
TiAl Intermetallic: Electronic Structure and Chemical Shifts
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  Abstract: First-principles calculations of the electronic structure of γ-TiAl intermetallic are performed in comparison with pure Ti and Al. Interrelation between the crystal structure, elemental composition, and electronic structure of γ-TiAl is discussed. The energies of inner electronic levels are found taking into account the excited state, which is characteristic of the X-ray photoelectron spectroscopy (XPS), and the chemical shifts of the main XPS lines of γ-TiAl with respect to the lines of pure Ti and Al are determined. The results agree with experimental data.
  PubDate: 2022-12-09
High-Resolution Spectroscopy of Asymmetric Top Molecules in Non-Singlet
Electronic States: ν1 + ν3 Band of the ClO2 Molecule
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  Abstract: Using a Bruker IFS 125 HR Fourier spectrometer, the high-resolution spectrum of the 16O35Cl16O molecule is recorded in the region of the \({{\nu }_{1}} + {{\nu }_{3}}\) band, in which more than 2000 transitions with the maximum quantum numbers Nmax = 59 and \(K~_{a}^{{\max }}\) = 16 are identified. The obtained experimental data are analyzed based on the model from the work [Phys. Chem. Chem. Phys. 23 (8), 4580–4596 (2021)], which takes into account the existence of spin-rotational interactions in the molecule. The root-mean-square deviation of rotational–vibrational energies from the calculated values for the (101) state was \({{d}_{{{\text{rms}}}}}\) = 2.5 × 10–4 cm–1, which is 35 times better than the data known from the literature.
  PubDate: 2022-11-29
Dispersion of Polariton Excitations in Atomic Cryocrystals in the Vicinity
of the Quadrupole Allowed Exciton Resonance Frequency
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  Abstract: The propagation of exciton-polariton excitations in atomic cryocrystals in the vicinity of the quadrupole allowed exciton resonance frequency is considered. The structure of the local electromagnetic field in a molecular crystal in the vicinity of the isolated quadrupole transition frequency in the molecular spectrum is studied and the tensor of quadrupole polarizability of a unit volume of a cubic crystal is obtained. The features in the dispersion of exciton polaritons reflecting the presence of additional light waves in the investigated vicinity of frequencies are studied.
  PubDate: 2022-11-29
Observation of Calcium Atomic Fluorescence in Laser-Induced Plasma with
High Spatial Resolution
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  Abstract: Optimum experimental parameters for studying distribution of calcium atoms in laser-induced plasma at low pressure (16 Torr) by means of atomic fluorescence are determined. The scheme of nonresonant fluorescence based on transitions between 4s4p (3P°)–4p2 (3P) states at 428.30 and 430.25 nm is proposed and implemented for excitation and observation of fluorescence for the first time. Based on analysis of the influence of crater deepening on intensity of fluorescence signal and comparison of fluorescence saturation curves, we demonstrate that a pure calcium carbonate is preferable as a target for observation of fluorescence. Substantial (by a factor of 62) enhancement of the fluorescence signal under optimum conditions allows neglecting the contribution of spontaneous emission to line intensities. We also demonstrate that temperature has low impact on population of the level used for excitation of fluorescence in the temperature range observed in the laser-induced plasma. These circumstances allowed spatially measurements to establish the lateral distribution of calcium atoms in plasma after optimization of parameters.
  PubDate: 2022-11-29
Structure of Pentafluoridozirconic Acid Crystallohydrates According to
Vibrational Spectroscopy Data
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  Abstract: Pentafluoridozirconic acid crystallohydrates HZrF5·3H2O and HZrF5·2H2O, as well as the intermediate product of their thermal decomposition ZrF4·H2O, are studied by vibrational spectroscopy and thermogravimetry. It is shown that HZrF5·nH2O (n = 2, 3) crystallohydrates are salts with complex cations H5O \(_{2}^{ + }\) and H7O \(_{3}^{ + }\) . The bands in the IR and Raman spectra are assigned based on the results of quantum-chemical calculations.
  PubDate: 2022-11-29
Photoplethysmographic Imaging of Hemodynamics and Two-Dimensional Oximetry
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  Abstract: The review of recent papers devoted to actively developing methods of photoplethysmographic imaging (the PPGI) of blood volume pulsations in vessels and non-contact two-dimensional oximetry on the surface of a human body has been carried out. The physical fundamentals and technical aspects of the PPGI and oximetry have been considered. The manifold of the physiological parameters available for the analysis by the PPGI method has been shown. The prospects of the PPGI technology have been discussed. The possibilities of non-contact determination of blood oxygen saturation SpO2 (pulse saturation O2) have been described. The relevance of remote determination of the level of oxygenation in connection with the spread of a new coronavirus infection SARS-CoV-2 (COVID-19) has been emphasized. Most of the works under consideration cover the period 2010–2021.
  PubDate: 2022-11-29
Account for the Inertial Term in the Navier–Stokes Equation in the Model
of Magnetohydrodynamic Domains for Nematics with Negative Anisotropy of
Diamagnetic Susceptibility
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  Abstract: A model of magnetohydrodynamic domains describing the motion of a nematic liquid with a negative diamagnetic susceptibility in the torsional deformation geometry is considered. The inertial term in the Navier–Stokes equation is taken into account. This made it possible to introduce into the model three dimensionless parameters, namely, the ratios of the Ericksen numbers to the Reynolds number, which do not depend on the characteristic values of the problem studied but are determined only by the parameters of the medium. Experimental determination of these parameters by observation of magnetohydrodynamic domains makes it possible to estimate the relative roles of elastic and viscous forces in nematics of different natures.
  PubDate: 2022-11-10
  DOI: 10.1134/S0030400X22070025
Thin Film Polarizers: Properties and Technologies. Part 1
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  Abstract: The manufacturing technology of many types of thin-film polarizers and options of their application assign such polarizers to the liquid crystals sciences. We present an analytical review of patent and scientific publications on the development of thin-film (no more than a few micrometers) linear and circular polarizers based on different physical principles (absorption dichroism, anisotropic luminescence, double refraction, reflection and scattering). The review is divided into two parts. The second part of the review describes structures and media, such as lyotropic and thermotropic liquid crystals, photoanisotropic materials, materials polarization-anisotropic light scattering or anisotropic fluorescence, and other media. Polarizers based on lyotropic liquid crystals, media with polarization-anisotropic optical properties, metallic grid structures, and media based on anisotropic luminescence are of greatest practical interest. To create patterned polarization structures with kinematic color and/or stereoscopic effects, lyotropic compositions in combination with photo-orientation are in highest demand, which is currently widely used for photo-orientation of thermotropic liquid crystals.
  PubDate: 2022-11-10
  DOI: 10.1134/S0030400X22070050
Electrical Properties of a Composition Based on Polydimethylsiloxane
Filled with Gallium Oxide
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  Abstract: In the present paper, the effect of gallium β-oxide introduced into the polydimethylsiloxane elastomer on the electrical properties of the composite material is investigated. The dependence of the electrical resistance of the composition on the change in the specific volume electrical conductivity on the content of gallium oxide was experimentally established and the percolation point was determined. The percolation point was 21%, which is slightly higher than the theoretical value calculated by the Monte Carlo method and is 16%. The temperature dependence of the electrical resistance of the composition on the content of the semiconductor filler in the binder is determined. The dielectric characteristics of the material, such as the tangent of the dielectric loss angle and the permittivity, were studied using the waveguide method on a laboratory stand based on a precision measuring line P1-20. The dielectric characteristics were calculated by changing the displacement of the standing wave nodes in the waveguide when a dielectric was placed in it using the MathCAD program. An experiment to determine the tangent of the dielectric loss angle in the entire X-band from 8 to 12 GHz showed that the introduction of gallium oxide leads to an increase in the dielectric losses in the composition. Additional dielectric losses in the composition occur with increasing frequency. The dielectric characteristics are significantly degraded when the filler content exceeds 20% (by volume). The influence of the filler on the radio-transparent and radio-absorbing properties of the polymer composition in the centimeter microwave range is studied. The results of the work can be applied in various sectors of the national economy, including radio electronics, microwave technology and medical technology to partially reduce the background of electromagnetic radiation.
  PubDate: 2022-11-10
  DOI: 10.1134/S0030400X22070013
Thin Film Polarizers: Properties and Technologies. Part 2: Lyotropic LC
and Photoanisotropic Materials
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  Abstract: This part of the review describes structures and media, such as lyotropic and thermotropic liquid crystals, photoanisotropic materials, materials polarization-anisotropic light scattering or anisotropic fluorescence, and other media. Polarizers based on lyotropic liquid crystals, media with polarization-anisotropic optical properties, metallic grid structures, and media based on anisotropic luminescence are of greatest practical interest.
  PubDate: 2022-11-10
  DOI: 10.1134/S0030400X22070062
The Influence of Chlorides on the Spectral Properties of Ion-Exchange
Layers of Photo-Thermo-Refractive Glass
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  Abstract: The influence of chlorides on the spectral properties of silver nanoparticles in ion-exchange layers of photo-thermo-refractive glass is studied. It is shown that silver particles in ion-exchange layers of photo-thermo-refractive glass without chlorides are formed only in the UV-irradiated region and the refractive index does not change under UR irradiation. It is found that UV irradiation and subsequent heat treatment lead to the growth of NaF crystals on Ag–AgCl/NaCl core–shell nanoparticles formed in UV-irradiated ion-exchange photo-thermo-refractive glass with chlorides. The difference between the refractive indices of the irradiated and non-irradiated regions of photo-thermo-refractive glass with chlorine reaches Δn = –3 × 10–3. The investigation results demonstrate the possibility of recording amplitude and amplitude–phase g-ratings in ion-exchange layers of chloride-free and chloride-doped photo-thermo-refractive glasses, res-pectively.
  PubDate: 2022-11-10
  DOI: 10.1134/S0030400X22070074
A New Class of Exact Solutions to the Navier–Stokes Equations with
Allowance for Internal Heat Release
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  Abstract: New exact solutions to the three-dimensional Navier-Stokes equations, which take into account energy dissipation in the equation of heat transfer in a moving fluid, are presented. The flows of viscous incompressible fluids can both steady and unsteady. The new solutions are based on the Lin-Sidorov–Aristov class of exact solutions. The characteristic feature of the velocity field representation is that it is described by linear forms with respect to two coordinates (horizontal or longitudinal). The coefficients of the linear forms depend on the third coordinate (vertical, or transverse) and time. The fluid pressure and temperature are quadratic forms with a similar structure for the velocity. This family of exact solutions describes the flows of viscous incompressible fluids with a spatial acceleration. In other words, allowance is made for nonlinear effects of inertia forces, which are expressed through the convective derivative of the velocity and temperature vectors in the Navier–Stokes and the heat conduction equations, respectively. Due to the energy dissipation in fluids, two quadratically nonlinear effects compete. This significantly complicates the study of flows, because of which the paper presents formulas describing a creeping flow (the Stokes approximation) and Oseen motion. Thus, the study shows the possibility of constructing exact solutions to the motion equations with mechanical energy dissipation into thermal energy for the full Navier–Stokes equations and for their linearized analogs in the Stokes and Oseen approximations.
  PubDate: 2022-11-10
  DOI: 10.1134/S0030400X22070037
Investigation of Specific Features of Recording the Optical Response of
X-Ray Phosphors for X-Ray Photodynamic Therapy
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  Abstract: A system for studying the optical response of X-ray phosphors, considered as a constituent of co-mposite materials for X-ray photodynamic therapy, is described. The concept and main principles of X-ray photodynamic therapy are presented. The test results for the designed system are shown, and techniques of optimization of the signal-to-noise ratio by varying X-ray source parameters and the geometry of the experiment are discussed. Examples of XEOL measurements for concentrated powder samples and dilute samples in the form of colloidal solutions are considered.
  PubDate: 2022-11-10
  DOI: 10.1134/S0030400X22070086
Search and Recognition of the Studied Area in Probe Microscopy Using
Markings Applied by Power Lithography or Nanoindentation
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  Abstract: This paper describes processes of search and recognition of a marked zone in scanning probe microscopy. Reference marks applied using a nanoindenter or a probe microscope cantilever are considered as marking. Typical images of reference marks are presented. Possibilities of a freely distributable software for distinguishing and recognition of reference marks on different types of images are considered. It is shown that some binarization methods and the cross-correlation method of template matching are suitable for referencing of marks. These methods turn out to be effective provided that algorithms of key point filtering are developed; it is proposed to use local extreme values of the correlation function as key points. An algorithm of such filtering based on varying threshold values of the correlation coefficient and size of the key point neighborhood is presented. The method of structural analysis based on determination of distances between key points of the image is proposed for recognizing reference marks. The results of recognition for various types of images are presented.
  PubDate: 2022-11-10
  DOI: 10.1134/S0030400X22070049
Features of the Dynamics of the Photoluminescence Spectrum of the Cu3In5S9
Crystal with a Change in the Intensity of Laser Excitation
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  Abstract: Photoluminescence spectra have been studied on the naturally formed surface of a layered Cu3-In5S9 crystal when excited by nanosecond laser radiation. At relatively low levels of optical excitation intensity, luminescence quenching was detected near the photon energy of 1.636 eV, in a narrow energy band—118 MeV. This phenomenon is explained by the formation of bound excitons of a triplet nature and their dissociation with the emission of phonons. It is shown that with an increase in the intensity of optical excitation of the crystal, the impurity band of radiation in the crystal disappears. The spectrum of the Cu3I-n5S9 photocurrent at 295 K is formed by peaks at energies of 1.53 and 1.81 eV. The lifetime of nonequilibrium electrons through fast centers is ~20 ns. From the temperature dependence of the electrical conductivity of the Cu3In5S9 crystal in the range of 110–350 K, the activation energies of two donor levels were determined: 0.28 and 0.76 eV.
  PubDate: 2022-08-30
  DOI: 10.1134/S0030400X22060030
Methods for Reducing the Sensitivity of Narrow-Band Light Filters to the
Angle of Incidence of Light
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  Abstract: The influence of the angle of incidence of light on the main characteristics of narrow-band interference light filters has been considered. It is shown that filters with a minimum half-width are most sensitive to the increase in the angle of incidence. A method of redesigning a light filter has been considered, which makes it possible to reduce the light-filter sensitivity to the angle of incidence of light. The stability of the transmission peak position on the wavelength scale can be increased by introducing a special layer into the construction of the light filter; this layer is made of material, which has not been used to prepare mirrors entering this filter. An increases in the refractive index of the spacer layer by 21% leads to an increase in the stability of the transmission band position at the level of 0.99λmax on the angular scale by 11%; the position stability for narrow-band filters consisting of 31 layers increases by 8% with an increase in the refractive index by 10%.
  PubDate: 2022-08-30
  DOI: 10.1134/S0030400X22060029
Switching Effects in Plasmonic Circuits Based on Thin Metal Films and
Nanostructures with High Photoconductivity
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  Abstract: Specific features of optical control of propagation of surface plasmon polaritons in plasmonic circuits based on thin metal waveguides and semiconductor nanostructures are considered. A model of plasmonic resonator with additional semiconductor elements, exhibiting strong photoconductivity, is proposed. Numerical simulation is used to show the possibility of switching the surface plasmon polariton flow in a plasmonic circuit by switching on/off the external optical pump field, changing the contribution of light-induced conductivity of control elements.
  PubDate: 2022-08-30
  DOI: 10.1134/S0030400X22050022
Stacking Aggregation and Photodimerization of Thymine Chromophores in
Aqueous Solutions of Polythymidylic Acid
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  Abstract: Heterogeneity of aqueous solutions of polythymidylic acid (poly-T) at room temperature is established by luminescence and absorption spectroscopy. It is found that there exist two fractions of thymine chromophores: (1) a photoactive fraction consisting of two types of stacking aggregates with a structure optimal for photodimerization, the first type having absorption bands at 250 and 280 nm (exciton splitting 4300 cm–1), and the second type, at 260 and 290 nm (exciton splitting 4000 cm–1), and (2) a photochemically intact fraction with an absorption maximum at 270 nm without evidence of exciton splitting, which probably consists of relatively isolated chromophores.
  PubDate: 2022-08-30
  DOI: 10.1134/S0030400X22050034
Correlation between the Efficiency of Singlet Oxygen Generation and the
Luminescence Parameters of Photosensitizers
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  Abstract: The quantum yield of interconversion to triplet states for free-base 2,3,7,8,12,13,17,18-octaethylporphyrin and 5,10,15,20-tetraphenylporphyrin, as well as of metallocomplexes with Mg(II), Zn(II), Pd(II), and Pt(II) ions, have been defined based on the data on the efficiency of photosensitized singlet oxygen generation. The quantum yields of singlet oxygen generation were measured for above mentioned compounds in different solvents. The maximum values of quantum yields of singlet oxygen generation are take place for compounds with heavy ions of Pd(II) and Pt(II) that due to intensification of internal heavy atom effect on intersystem crossing. The high quantum yields of singlet oxygen generation for case of free-base porphyrins indicate strong spin–orbit coupling in the absence of the internal heavy atom effect for these compounds. The specific features of the internal heavy atom effect on the triplet state deactivation rates for some porphyrins with Pd(II) and Pt(II) ions at room temperature and at 77 K were estimated.
  PubDate: 2022-08-30
  DOI: 10.1134/S0030400X22050046