


Vol 126, No 5 (2019)
- Year: 2019
- Articles: 25
- URL: https://journal-vniispk.ru/0030-400X/issue/view/10108
Spectroscopy and Physics of Atoms and Molecules
Influence of the Density of Buffer Gas Atoms on the Shape of the HgXe(A30+) → HgXe(X10+) Excimer Band
Abstract
The reasons for the discrepancies between the experimental data on the shape of long-wavelength continua near the 63P1 → 61S0 resonance line of a mercury atom in a xenon atmosphere obtained by different authors are analyzed. Calculations of spectral profiles for limiting cases of high and low densities of buffer gas atoms lead to the conclusion that the discrepancies are mainly due to the dependence of the rates of three-particle recombination and relaxation processes on the xenon density. Different types of a non-equilibrium or almost equilibrium (at high xenon concentrations) population of rovibrational states of a HgXe(A30+) excimer molecule are formed at different rates of these processes, which affects emission spectral profiles.



Spectroscopy of Condensed States
Optical and Photoelectric Properties of GaS Thin Films and GaS/InSe Heterostructure
Abstract
GaS thin films have been grown by the SILAR method, their structures have been analyzed, and their optical and photoelectric properties have been investigated. The internal structure of the samples obtained have been studied using X-ray diffraction (XRD) analysis, atomic force microscopy (AFM), energy-dispersive X-ray (EDX) spectroscopy, and scanning electron microscopy (SEM). The GaS band gap has been determined from the absorption spectrum. p-GaS/n-InSe heterojunctions have been formed on the basis of GaS crystals and InSe thin films. Current–voltage, optical, photoelectric, and luminescence characteristics of p-GaS/n-InSe heterojunctions have been experimentally investigated.



Fluorescence of N,N'-Bis(salicylidene)-1,3-propylenediamine and Its Halogen Derivatives in a Perfluorosulfonic Membrane
Abstract
Film phosphors are obtained by adsorption of N,N'-bis(salicylidene)-1,3-propylenediamine and its halogen derivatives from their ethanol solutions by a perfluorosulfonic membrane. Fluorescence bands with maxima at 440–460 nm are determined by the polarized state of the molecules in the membrane. We propose to consider the antibonding \(\pi _{{{\text{(N=C)}}}}^{{*}}\) states of the azomethine fragments (HC=N–) of the molecules as emitting ones.



Physical Optics
Solution of Problems of Wave Scattering by Bodies Having Boundary Breaks and Fractal-Like Bodies of Rotation
Abstract
Based on the method of continued boundary conditions, a technique is proposed that allows one to model the scattering characteristics, including averaged over orientation angles, for bodies of practically any geometry. A number of examples of solving problems of diffraction on fractal-like bodies of revolution are given. The correctness of the method is confirmed by verifying the implementation of the optical theorem for various bodies and by comparing with the results of calculations obtained by the method of discrete sources.



Nonlinear Optics
The Influence of the Properties of the Interface between Linear and Nonlinear Optical Media on the Energy Fluxes of Nonlinear Surface Waves Propagating along the Interface
Abstract
Processes of localization of field excitations in the form of nonlinear surface waves that propagate along the interface between linear and nonlinear media are considered. The existence conditions of nonlinear surface waves, which are determined by the ratio between the linear characteristics of the media, the Kerr nonlinearity coefficient, and the intensity of interaction of the wave with the interface, are analyzed. The dependences of the energy flux carried by nonlinear surface waves are calculated and analyzed. Two approaches are proposed to selection of the control parameters for determining the energy flux, which are the position of the maximum field perturbation in the nonlinear halfspace and the field amplitude at the interface. Estimates of the fluxes are found in different limiting cases, which correspond to small-amplitude field perturbations and to weak or strong interaction of a nonlinear surface wave with the interface between the media. It is shown that, in the case of small-amplitude field perturbations and the weak interaction of the wave with the interface, the flux in the linear halfspace is directly proportional to the interaction intensity of the wave with the interface, while that in the nonlinear halfspace is inversely proportional to the interaction intensity.



High-Power Fields and Ultrashort Optical Pulses
Three-Dimensional Extremely Short Optical Pulses of Airy in a Photonic Crystal with Carbon Nanotubes
Abstract



Optics of Low-Dimensional Structures, Mesostructures, and Metamaterials
Structure and Optical Characteristics of Barium–Strontium Niobate Films on Al2O3 Substrates
Abstract
The structure and optical characteristics of thin films of relaxor ferroelectric Ba0.5Sr0.5Nb2O6 grown by RF sputtering in an oxygen atmosphere on an Al2O3 substrate (c cut) have been studied. X-ray diffraction analysis shows that Ba0.5Sr0.5Nb2O6 films are c-oriented and unit-cell parameter c is 3.948(1) Å. Ellipsometric measurements confirm that SBN-50 films are characterized by a natural growth direction, which coincides with the direction of the optical crystal axis. An analysis of ellipsometric results shows that there is no transition layer at the film/substrate interface; the damaged layer on the free film surface is 7.5 nm thick, and the volume filling factor is estimated to be 0.625.



Epitaxial InGaAs Quantum Dots in Al0.29Ga0.71As Matrix: Intensity and Kinetics of Luminescence in the Near Field of Silver Nanoparticles
Abstract
Quantum dots of indium gallium arsenide buried in a thin layer of aluminum gallium arsenide were grown by means of molecular-beam epitaxy. The influence of silver nanoparticles grown on the surface of the semiconductor structure by vacuum thermal evaporation on photoluminescence of quantum dots was investigated. Photoluminescence spectra of quantum dots were obtained under stationary and pulsed excitation. The influence of silver nanoparticles exhibiting plasmon resonances on spectral distribution and kinetics of luminescence of the epitaxial quantum dots was studied.



Optics of Surfaces and Interfaces
Spin Angular Momentum of a Nonlinear Surface Wave at the Interface between Ordinary and Topological Insulators
Abstract
The surface waves that propagate along the interface of a dielectric with nonlinear susceptibility of the third order and topological insulator have been considered. The optical nonlinearity of the dielectric ensures the existence of a surface wave. The density of the spin angular momentum of a surface wave has been determined for dielectrics with positive or negative linear permittivity. It has been shown that the spin angular momentum vector has a projection on the normal to the interface, which is different from the usual surface polaritons or plasmon polaritons. The discrete nature of the topological number manifests itself in the discreteness of the values of the normal and tangential components of the spin angular momentum density. The increase in the intensity of the electric field of the wave at the interface of the media changes the value of the spin angular momentum and can lead to its disappearance.



Biophotonics
Differentiation of Pigmented Skin Lesions Based on Digital Processing of Optical Images
Abstract
A method for differentiation of pigmented skin lesions is proposed that is based on digital processing of optical images. The optical images are detected using a digital camera and a standard for its color and spatial calibration. The method involves segmentation and automatic recognition of neoplasms on the basis of five parameters: diameter, area, color, shape, and border sharpness. The analysis reveals clinical features of the lesion, required for diagnosis, and allows for calculating the probability of its malignant transformation. The method proposed was tested on 360 digital images of in vivo skin pigment lesions, including ordinary dysplastic nevi and melanoma. The sensitivity and specificity of the method proved to be 97 and 95%, respectively.



Electrodynamical Characteristics of α-Lactose Monohydrate in the Terahertz Range
Abstract
Using methods of infrared, terahertz, and submillimeter spectroscopy, experimental transmission and reflection spectra of α-lactose monohydrate have been obtained at room temperature in the frequency range from 5 to 5000 cm–1. The experimental spectra of dense pressed tablets and powdered samples have been analyzed in terms of the model of a classical oscillator. Certain parameters of absorption bands of the resonant and quasi-relaxation types are markers by which components can be selected in heterogeneous pharmacological and organic preparations using the methods of coherent submillimeter and pulsed terahertz spectroscopy.



Use of Terahertz Spectroscopy for in vivo Studies of Lymphedema Development Dynamics
Abstract
A laboratory model of lymphedema development induced by lymphatic vessel resection in rat extremities is presented. In vivo analysis of lymphedema development (monitoring for 4 weeks) employed reflective terahertz spectroscopy with a Dove prism. The incidence angle for an s-polarized electromagnetic wave directed to the boundary of the prism and the biological tissue was close to the Brewster’s angle. Significant changes in the spectral characteristics of the tissue in the animals’ extremities were detected on days 21–28 of lymphedema development. A predictive model for disease diagnostics based on monitoring the changes of the tissue absorbance curve in the 0.4–1.1 THz range was constructed. Principal component analysis and support vector machines were used in the model.



Fluorescent Microscopy Analysis of Mammalian Oocyte Viability after Vitrification
Abstract
The paper reports the results of a fluorescent microscopy analysis of the viability of oocytes from cattle and pigs after vitrification. Oocytes were frozen in a vitrification media containing varying concentrations of cryoprotectors in several steps with subsequent vitrification. After cryobank storage for 14 days, experimental samples were thawed and oocyte viability was analyzed by oocyte morphology assessment and fluorescent microscopy. Two different kits were used to stain oocytes, one specific for necrosis/apoptosis (Propidium iodide/Alexa Fluor 488 Annexin) and the other specific for live/dead cells (Calcein-AM/ethidium homodimer-1). Fluorescent microscopy of porcine and bovine oocytes has demonstrated that the fluorescent dye Calcein-AM should be chosen to assess oocyte viability, since Propidium iodide and ethidium homodimer-1 do not represent the oocyte cell death. Therefore, Propidium iodide and ethidium homodimer-1 cannot serve as indicators of real oocyte death.



Microcrystalline Diamond Powders As Promising Objects for Generation of Multifrequency Stimulated Raman Scattering
Abstract
Regular trends of Raman scattering in microcrystalline diamond powders as a function of size of the diamond microcavities are investigated in the range of the latter between 1 to 600 μm. The observed effect of anomalously high intensity of spontaneous Raman scattering is attributed to “trapping” of electromagnetic radiation with a wavelength shorter than the size of the diamond microcrystals in diamond microcavities. The electromagnetic energy density for the driving and secondary radiation increases as a result of photon “trapping” in the diamond microcavities. A high Q factor of the fundamental optical mode in the vibrational sp-ectrum of diamond and anomalous increase in the Raman scattering intensity in diamond microcavities pave the way for observation of the low-threshold multifrequency Raman scattering in microcrystalline diamond powders. Using the radiation of a pulsed solid state YAG:Nd3+ laser at the fundamental wavelength (λ = 1064 nm) and its optical harmonics (λ = 532, 355, 266 nm) as sources of driving radiation opens up a possibility for creation of an array of equidistant (with respect to frequency shift) laser sources with wavelengths extending from the ultraviolet to the terahertz range promising for investigation of biological and medical objects.



Spectral Monitoring of Naftifine Immobilization into Submicron Vaterite Particles
Abstract
Development of novel drug delivery systems providing the enhanced accumulation of the therapeutic agents in the area of pathology reducing in the meantime the systemic toxic effects is of great research interest. Here we introduce the study on the antifungal drug “Naftifine” immobilization into the particulate delivery system based on vaterite submicron particles. Two different techniques are proposed for the antimycotic incorporation: adsorption onto the surface of freshly-prepared vaterite particles from the drug solution and co-precipitation of the drug molecules during the particle synthesis. Various optical methods were used to investigate the immobilization process. Thus, laser Raman spectroscopy was used to confirm the successful carrier loading with naftifin hydrochloride. A spectrofluorimetric method was applied for the quantitative determination of the drug loading efficiency into vaterite matrix. The study revealed that the co-precipitation technique allows the immobilization of the highest antimycotic percentage (9 wt %). Scanning electron microscopy was used to monitor the stability of the naftifin-loaded carriers under their incubation in deionized water, saline and cell culture medium. The slowdown of vaterite recrystallization process was observed for the protein-containing medium. Such effect holds out the prospect of drug release prolongation for the future application of the proposed carries in living systems.



Sapphire Neurosurgical Probe for Aspiration of Brain Tumors with Boundary Demarcation by Use of Spectroscopy
Abstract
A contact sapphire neurosurgical probe for the removal of brain tumors with the possibility of intraoperative exogenous fluorescence diagnostics and laser coagulation of adjacent blood vessels has been developed. The geometry of the sapphire neuroprobe has been optimized to increase the sensitivity of fluorescence diagnostics. For this purpose, a series of computational experiments have been performed using the Monte Carlo method. The technique for growing a sapphire shaped crystal with a variable cross section has been developed. Using this technique, a pilot prototype of the sapphire neuroprobe has been manufactured. The sample has been approbated experimentally.



Photoinduced Enhancement of Evans Blue Dye Fluorescence in Water Solution of Albumin
Abstract
The effect of photoinduced enhancement of Evans blue (EB) dye fluorescence in blood plasma and albumin solution has been considered. Manifestations of the dye fluorescence enhancement in the albumin solution and rat blood plasma have been compared. Saturation of photoinduced fluorescence, the effect of enhanced fluorescence delay, and divergence in fluorescence spectra of the solutions have been found for the first time. Based on the obtained results, a hypothesis about the presence of nonfluorescent complexes with the EB participation in blood plasma is proposed.



Terahertz Microscope Based on Solid Immersion Effect for Imaging of Biological Tissues
Abstract
We propose a new method of terahertz microscopy for imaging of biological tissues with a subwavelength spatial resolution. It makes it possible to surmount the Abbe diffraction limit and ensures a subwavelength resolution due to the solid immersion effect, i.e., due to decreasing dimensions of the electromagnetic beam caustic as the beam is focused in free space at a small distance (smaller than the wavelength) behind a medium with a high refractive index. An experimental setup that realizes the proposed method is developed. It uses a backward-wave oscillator and a Golay cell as a source and a detector of the terahertz radiation, respectively. In this setup, the radiation is focused behind a silicon hemisphere to realize the solid immersion effect. A record-high spatial resolution of 0.15λ is demonstrated experimentally for optical systems based on the solid immersion effect (the measurements have been performed at a wavelength of λ = 500 μm using a metal–air interface as a test object). Microscopy based on the solid immersion effect does not imply using diaphragms or near-field probes of other types for achieving the subwavelength spatial resolution, and, correspondingly eliminates energy losses associated with these elements. The proposed method has been applied for imaging of soft biological tissues, which has made it possible to demonstrate its potential for the use in biology and medicine.



New Opportunities for Colorectal Cancer Diagnostics Using an Optical Cell Detection System Based on Dielectrophoresis
Abstract
The possibilities of using electrical and viscoelastic parameters of erythrocytes in patients with colorectal cancer (CRC) of different stages were demonstrated using optical cell detection system based on the dielectrophoresis method. The deformation amplitude, portion of deformed cells, generalized viscosity, rigidity, equilibrium frequency position, and electrical conductivity were the most significant parameters for determining patients with CRC, as well as early and late stages, included in the created model of a riskometer for the disease diagnosis. The created diagnostic “panels” with a high diagnostic accuracy, sensitivity, and specificity allowed to one determine patients with CRC (specificity 0.91, sensitivity 0.96), as well as early and late stages of the disease (specificity 0.64, sensitivity 0.86).



Optical Properties of Human Eye Cataractous Lens in vitro in the Visible and Near-IR Ranges of the Spectrum
Abstract
The spectral dependences of the absorption coefficient, scattering coefficient, scattering anisotropy factor, and transport scattering coefficient for human eye lens in vitro at different stages of cataracts were studied. The spectra of the absorption coefficient and transport scattering coefficient were obtained for the spectral range 400–2300 nm, and the spectra of the scattering coefficient and the scattering anisotropy factor were obtained for the spectral range 400–1800 nm. The wavelength regions in which the spectra of the studied optical characteristics of human eye lens do not differ significantly and, conversely, differ significantly for the samples with different stages of cataract were identified.



Plasmonic Photoconductive Antennas for Terahertz Pulsed Spectroscopy and Imaging Systems
Abstract
We propose a terahertz (THz) plasmonic photoconductive antenna (PCA) with a record height of its metal electrodes of h = 100 nm and a high aspect ratio of h/p = 0.5 (p is the period of the plasmonic grating) that can be used as a source is THz pulsed spectroscopic and imaging systems. We experimentally demonstrate that the power of the THz radiation generated by the proposed plasmonic PCA is two orders of magnitude higher than that of an equivalent ordinary PCA without a plasmonic grating. Current–voltage measurements of the thus developed plasmonic PCA under femtosecond laser excitation show that the photocurrent of the PCA increases 15-fold, up to ip ≈ 1.2 mA. To reduce the leakage currents of the PCA, we propose a fabrication technology that is based on the etching of windows in a thin Si3N4 passivation dielectric layer deposited on the photoconductor surface, which makes it possible to reduce the dark current to id ≈ 5 μA.



An Experimentally Trained Noise Filtration Method of Optical Coherence Tomography Signals
Abstract
A method for wavelet filtration procedure training for optical coherence tomography (OCT) images using the experimental measurements of test objects that were constructed by means of water solutions of monodisperse nanoparticles and several microscopic inclusions has been described in the present paper. The choice of test-object parameters (concentration of water solution, size of nanoparticles, and shape, dimensions, and mutual position of inclusions) has allowed the modeling of various working conditions of OCT and setting different criteria for estimation of filtration efficiency. In the present work, the optimal filter for the considered example of a test object has been selected among the combinations of various basic functions of five wavelet families, soft and hard threshold filtering methods, four decomposition levels, and threshold values in a range of 0.05–3.05. The mutual position of the micro-inclusions has been used as a criterion for evaluating the filtration efficiency. As a result, it has been shown that the determined wavelet filter leads to effective suppression of the scattering noise in OCT images and preserve information about the structure of the object under study.



Optical Digital Registration of Erythrocyte Sedimentation and Its Modeling in the Form of the Collective Process
Abstract
The dependence of the sedimentation rate of donor blood on its percentage in the sample (the degree of its dilution with physiologic saline) ranging from 0.25 to 100% (whole undiluted blood) is investigated with digital video equipment. The ratio of the value of displacement of the sediment–supernatant boundary per time unit was taken as the blood sedimentation rate. In case of registration of different speeds of movement of this boundary in a given volume of the cuvette, their spatial averaging was performed. A substantial increase in the blood sedimentation rate was found experimentally at high levels of its dilution, and, conversely, at blood concentrations in physiologic saline solutions that are close to whole blood. At the same time, the rate of blood sedimentation decreased several times with blood content in the range of 30–50%. It was experimentally shown that variation of blood content in the physiologic saline solution over a wide range did not affect the evenness of sedimentation occurring for almost any blood concentration in the mixture. In other words, in the process of sedimentation of a single blood sample of a given dilution in the physiologic saline solution, the sedimentation rate does not change with time. The experimentally obtained results allowed to build a theoretical model of blood sedimentation for two cases: 1) sedimentation of free erythrocytes (highly diluted blood) and 2) sedimentation of erythrocyte aggregates (almost undiluted blood, up to whole blood). The originality of the model comes from the proposition to consider the sedimentation of cells and/or their aggregates as a collective effect, and not in the traditional form of sedimentation of individual particles or particles interacting with each other. This model gives a satisfactory agreement with experimental laws with the use of certain empirical constants. The study is useful for understanding the process of erythrocyte sedimentation.



Applied Optics
Square Porous Core Microstructure Fiber for Low Loss Terahertz Applications
Abstract
A new kind of square lattice porous core microstructure fiber is proposed for promising low loss terahertz applications. To analyze the guiding characteristics of proposed fiber Finite Element Method (FEM) based Comsol V4.2 software is used. The proposed fiber structure is very simple and easy to realize. The numerical results ensures that this proposed microstructure fiber exhibits low effective absorption loss of 0.06 cm–1, low confinement loss of 9.2 × 10–3 cm–1, low bending loss of 8.8 × 10–9 dB/m, and very high power fraction of 47% through the core at 1 THz simultaneously. Moreover, our proposed fiber offers very low dispersion variation of 0.85 ± 0.12 ps/THz/cm over a wide range of frequency from 0.7 to 1.15 THz. The investigated results indicates that this fiber will be a good candidate in terahertz signal transmission as well as different terahertz devices.



Erratum


