This PDF file contains the front matter associated with SPIE Proceedings Volume 11322, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

Laser-induced fluorescence KA-14 LIDAR, developed and employed at the National Aviation Academy of Azerbaijan was used for detection of emission spectra of oil spills on the surface of the Caspian sea and earth surface of the Absheron peninsula. It is known, that oil spills may take place due to leakage of oil from different Oil-Gas-Production Companies and Joint Ventures of the State Oil Company of Azerbaijan Republic. There are 8 Oil-Gas-Production Companies and 4 Joint Ventures in Azerbaijan Republic. Fluorescence spectra were excited by 355 nm line of CFR 200- type laser (QUANTEL) with parameters: diameter of laser beam spot- &diameter; = 5 mm (after collimation- 40 mm); frequency of excitation- f = 20 Hz; pulse duration and power of laser- τ= 7 ns and 60 mJ, respectively. Analysis of differences of the spectral positions of maximums of fluorescence spectra, forms of the emissions spectra, as well as peculiarities of fine structures in emission spectra allowed with a high degree of availability to determine from which Oil-Gas-Production Company of State Oil Company of Azerbaijan Republic (including OGPC “Neftjanije Kamni”) leakage took place on the surface of the Caspian sea and on the earth of Absheron peninsula. Results obtained allow, for the first time, to create a data bank of fluorescence spectra of crude oil extracted on the earth of the Absheron peninsula of Azerbaijan as well as from adjacent water areas of the Caspian sea, including OGPC "Neftjanije Kamni."

Excimer lamps take place among the numerous industrial applications which rely on cold plasmas generated by means of Dielectric Barrier Discharges. For the performance and reliability of these applications, the control of the electrical energy injected into the plasma is of prominent importance; it also contributes to the homogeneity of the electrical discharge and to the amount of created excited species, thus the UV emission. In this scope, we have developed generations of pulsed current power supplies aimed at controlling the energy of the injected pulses. For UV generation processes by means of excimer lamps, the design approach of two of the most performing topologies is presented. The performances are highlighted, as well as the pitfalls and solutions for their use. The critical impact of the high voltage transformer, through its parasitic parameters, is pointed out, as well as solutions trying to take advantage of them.

The problem of the propagation of a femtosecond laser radiation in the atmosphere remains relevant in the application to the problems of remote sensing. When radiation propagates in a multi-component dispersive medium, for example, atmosphere, two important facts are occurred. The first is the transformation of the spectral and spatial characteristics of the radiation. The second is the dispersion modification of the duration. The results of experiments to take into account the dispersion effect of a multi-component medium (atmospheric air) on the duration of a femtosecond wave packet propagating in the atmosphere are discussed.

This paper studies nonlinear optical properties of colloidal solutions obtained via pulsed laser ablation (PLA) of bulk targets of magnesium (Mg), bismuth (Bi), tin (Sn), and antimony (Sb) in water and ethanol. In this research Nd:YAG laser (1064 nm, 180 mJ, 7 ns, 20 Hz) was used as a radiation source. Nonlinear absorption and scattering of colloidal solutions were studied by direct nonlinear transmission (NLT) with power density in the range of 1-450 MW/cm². Except for the solution obtained through the ablation of magnesium in water, all the samples exhibit a nonlinear decrease of transmission as a consequence of the increase of pumping power density. Along with this, the effect of nonlinear limitation of laser radiation depends on the type of particles and solvents.

The influence of irradiation wavelength on the degradation of Bisphenol A (BPA) in water under the action of KrCl and XeBr excilamp radiation in a photoreactor is investigated. Fluorescent photoproducts of photodegradation of the investigated molecule is constructed. In the work fluorescent photoproducts are defined. In an excited state BPA exists in a dimeric form at a concentration above 0.1 mM. After excitation by an excilamp the main BPA photoproduct fluoresces in the region of 420 nm. This behavior is explained by the fact that the action of 222 nm radiation leads to accumulation of a stable photoproduct. This product is destroyed as well as BPA after 120 minutes of exposure. Under the action of XeBr excilamp radiation a very stable product is formed with fluorescence at 380 nm. In order to establish the mechanism of BPA photolysis the product using chromatomass spectrometryfurther research is needed.

Melanogenesis disorder leads to several pathologies, including vitiligo. Tetrahydrobiopterin (H₄Bip) as the phenylalanine 4-hydroxylase coenzyme catalyzes the oxidation of phenylalanine to tyrosine (a melanin precursor). H4Bip is easily oxidized by oxygen in vivo and in vitro. Vitiligo is accompanied by three-fivefold increased de-novo synthesis of H₄Bip, its excess and its further oxidation are essential factors in the pathogenesis of vitiligo. We have demonstrated that pterin products of H₄Bip autoxidation (dihydropterin (H₂Ptr), dihydroxanthopterin and pterin) predominate over biopterin products (dihydrobiopterin (H₂Bip) and biopterin). It was shown that ultraviolet (UV) irradiation accelerates the autoxidation while the products of oxidative degradation of H₄Bip act as photosensitizers. Photosensitized oxidation of H₄Bip can contribute to the pathogenesis of vitiligo. The main distinguishing feature of UV photooxidation of H₄Bip from autoxidation was the formation of dihydropterin (Н₂Ptr)₂ and dihydrobiopterin (Н₂Bip)₂ dimers. Here we reported on the dependences of the photodimerization reaction on the wavelength and intensity of radiation using xenon lamps and UV tunable lasers as sources of UV radiation. It was shown that UV irradiation with a laser is more efficient than that with xenon lamp. It was established that the greatest number of dimers were formed by irradiating the H₄Bip solution by radiation with a wavelength in the range 308-312 nm. The data obtained are discussed in the context of UVB narrowband vitiligo phototherapy.

It was demonstrated that the amount of Ce³⁺ ions in centers with luminescence in the shorter wavelength region decreases and with luminescence in the longer wavelength increases upon transition from LiSrAlF₆ to the LiCaAlF₆ matrix. In this case, the longer wavelength edge of the excitation band corresponds to the luminescence of longer wave centers in the LiCaAlF₆ matrix, while the opposite is observed for the LiSrAlF₆ matrix. The picture also changes with an increase in the concentration of Ce³⁺ ions, namely, an increase in the luminescence intensity of longer-wave centers is observed; It is shown that mixed crystals at a low concentration of Ce³⁺ ions are characterized by a higher gain. In this case, the effect of the formation of color centers and induced absorption appears for LiSrAlF₆ crystals and mixed LiSr_xCa_1-xAlF₆ with an increase in the concentration of Ce³⁺ ions.

The intensive development of beam, plasma, discharge and laser technologies makes non-destructive testing methods and devices based on passive and active optical systems. There is an active optical system, which is called a laser monitor. The using of this system makes it possible to form images of test objects and processes suitable for analysis even under background radiation, however, the imaging distance does not exceed 3.3 m. The bistatic scheme of the laser monitor is designed to expand the capabilities of imaging using active media on metal vapors. This paper shows the operation features of the bistatic laser monitor as well as the parameters of the formed images. One of the issue is to compare the amplification of image brightness in an optical converter due to the different laser monitor scheme modification.

One of the approach to calculate the characteristics of the air refractive index fluctuations along line of sight for multiconjugated adaptive optics is based on the triangulating the wavefront distortions or/and scintillation amplitudes analysis. The description of the experiments aimed to measurements of the wavefront distortions and scintillation fluctuations is given. The scheme for recovering the optical distortions (wavefront) at the different heights is discussed. The results of changes of the wavefront distortions measured by Shack-Hartmann sensor in the spaced regions of images are discussed. The results obtained may be used for estimation of the real amplitudes of the wavefront distortions in crossed optical beams at the different heights using such method as SDimm+[ 5].

The article proposes a design of sensor of optical distortions in a wide field of view for the adaptive optical system of the Large Solar Vacuum Telescope. The calculation of the optical scheme of the sensor based on the use of two wavefront sensors was performed. The working field of view of the adaptive system with an additional sensor for determining the distortions of the wavefront is 120 arc sec. Adjusting the field of view of each Shack-Hartmann sensor up to 30 arc sec is provided by field diaphragms. It is shown that for the used second imager, the quality of subimages remains high, the standard deviation is λ /80.

In this work, the luminescent properties of three europium salts with various counterions (trifluoroacetate, nitrate and chloride) are studied. Their luminescence excitation spectra at room temperature and in liquid nitrogen have been recorded and studied. Their luminescence lifetime is determined when excited in the UV and visible regions of the spectrum. The influence of counterions and the number of water molecules in the structure of europium salts on their luminescent characteristics is determined.

The influence of the water on the stability of complexes of 6,6′-Bis(diphenylphosphinoyl)-2,2′-bipyridyl with lanthanide ions was studied. An increase in the stability value of the complexes is observed with a decrease in the ionic radius of the metal. An increasing of the water content in acetonitrile leads to decrease the stability of the complexes. Moreover the stability of the complexes became independent on ionic radii of metals.

The work presents the results of spectroscopic study of the natural water with microorganisms from the splash baths in the Atlasov Island (the Alaid Volcano). The Alaid Volcano is the highest, northernmost and one of the most active volcanoes of the Kuril Islands, the unique object for interdisciplinary research. In 2015 within the supralittoral zone of the island the several splash pools filled with colored marine water were discovered for the first time. The paper presents the results of spectral measurements and microbiological studies performed on natural water samples taken in 2015-2017 from the supralittoral zone of the Alaid Volcano, the Kuril Islands, as well as the photosynthetic microorganisms cultivated from those samples in laboratory. The absorption spectra of the native samples and the cultures of photosynthetic bacteria cultivated from original water demonstrated pronounced maxima at 380, 590, 806, 854 nm wavelengths and the shoulders peaked at 510, 590 and 890 nm. The observed absorption maxima revealed the presence of bacteriochlorophyll а, the main photosynthetic pigment of purple sulfur bacteria, and additionally the cells of purple sulfur bacteria Thiocystis and Thiorhodococcus morphotypes were detected in water under microscope. Observation of water colored by photosynthetic microbes in different parts of the Atlasov Island within several summer seasons in 2015-2017 allowed us to conclude that the development of the purple phototrophic bacteria in the splash baths above the littoral zone is not an accidental event, but the stable phenomenon. On the other Kuril Islands similar splash baths have not been encountered yet.

There are reported about investigation results which directed to the creation of pulse-periodical CO₂-laser working at super-atmospheric pressures. The main processes regulated volume discharge forming at total pressures up to 5 atmospheres and generation characteristics of CO₂–laser working at pulse repetition rates up to 2 kHz are studied. Maximum average radiation power 120 W is achieved. Minimal duration of laser pulses up to 15÷20 nanosecond are realized.

The results of numerical simulation of output radiation parameters and efficiency of inductive copper vapor laser (ICVL) of transformer type are presented. The influence of scaling of the ICVL on the possibility of its implementation in practice is analyzed. The parameters of the small-scale model of ICVL for the first experiments on the implementation of a new method of excitation by an electrode-free induction discharge for a copper vapor laser are determined.

The interaction of polychromatic radiation of a dye laser with a neon gas-discharge plasma in shielded cylindrical tubes at medium gas pressures (1-30 Torr) near atomic spectral absorption lines of NeI atoms with wavelengths 650.6 and 656.2 nm was experimentally studied. Along the direction of propagation of the laser radiation, a shift in the central frequency of absorption is observed in the presence of inhomogeneities in the plasma column. The character of the optical transmission spectrum near narrow resonances was empirically shown to substantially depend on the density of absorbing atoms in a plasma; if this density exceeds 10¹² cm^-3, the contour of the transmission spectrum near the absorption resonance acquires a dispersive form. The general laws of the formation of nonstationary plasma transmission spectra depending on the laser power, the density of absorbing atoms, the nature of plasma inhomogeneities along the direction of propagation of laser radiation are examined in detail. The role of nonlinear and coherent effects and phase self-modulation during resonant interaction of short pulses of polychromatic laser radiation with gas-discharge plasma in narrow shielded tubes is discussed.

There are described some constructions and generation characteristics of small–sized sealed–off metal–ceramic CO₂-lasers working at super atmospheric pressures with active discharge volumes V₁ =18×0.8×0.8 cm³ and V₂ =7×0.8×0.8 cm³ and resonator length 20÷46 cm. The main goal of this work was determination of main interrelations between gas discharge parameters, parameters of optical resonator and laser energy per pulse and laser pulse duration. There are achieved radiation pulses with a maximum energy per pulse up to 50÷150 mJ and with minimal durations 5÷8 nanoseconds at pulse repetition rates up to 20 Hz.

Analysis of experimental data obtained in study of cryogenic CO laser with glow discharge and cryogenic slab CO laser with RF discharge showed that oxygen concentration in laser mixture is much less than in initial gas mixture. With low oxygen content, ozone plays role of supplier of electrons in cryogenic discharge. Since ionization potential of ozone is somewhat higher than that of oxygen, and ozone quickly condenses on cold walls of cryogenic discharge, conversion of O₂ to O₃ is accelerated. In addition, in plasma-chemical reactions, ozone regenerates carbon monoxide after dissociation. Acceleration of ozone generation in cryogenic barrier discharge was experimentally demonstrated.

A set of output characteristics of copper vapor lasers with an average power level of 30-100 watts is considered. The radiation parameters of active media have been optimized for power consumption, buffer gas pressure of neon and hydrogen, repetition rate, and pump pulse parameters. A thyratron version of the switch was used as a pump generator; its high-voltage modulator has been made according to the capacity voltage doubling scheme with magnetic compression of the current pulses. We shall also discuss the issues of modifying the design of laser tubes (diameter is 4.5 cm, active length is 1520 cm) and the relationship with their lifetime. The issues of modern applications of high-power laser systems based on copper vapor are considered.

Depending on their origin and structure, humic acids (HAs) have a remarkable ability to absorb light and transfer this energy to other substrates and in some cases strongly affect photolysis of xenobiotics. This search exhibits several examples of spectral and fluorescent study of humics acids with different genesis. The group of studied HAs was isolated from an unditourified high-moor peat with different humidity in the Mezensky District of the Arkhangelsk Region. The standard commercial preparation of humic acids Aldrich was also studied. For photochemical studies, an excilamp on working molecules KrCl with λ_rad = 222 nm, developed at the Institute of High Current Electronics of the SB RAS, was used as sources of UV radiation. The results of direct and sensitized (in the presence of HAs) photolysis are discussed. For samples of HAs from the Arkhangelsk region, the dependence of the absorption spectra and fluorescence on the duration of drying and the depth of occurrence was found. The longer is the duration of drying of the samples, the lower is the optical density of the absorption spectra. In the process of humification and with the duration of peat drying, the fluorescence intensity of the HAs increases. The dependence of the fluorescence spectra of the studied samples on the wavelength of fluorescence excitation was found.

In this work we report on the results of synthesis and investigation of Fe²⁺:MgAl₂O₄ceramic samples. Nanopowders with small average particle size of ~ 18 nm were used for the preparation of the samples. It has allowed to synthesize the ceramics with an average grain size of 300–400 nm at a temperature as low as ~ 1200 °С. It was shown that the Fe ions occupy tetrahedral sites of lattice with a mandatory valence equaled to 2 when the content of iron in the samples of magnesium aluminate spinel is higher than 1 wt.%. Transmission of radiation in the samples increased with an increase in wavelength due to the reduction of Rayleigh scattering caused by pores. It was determined that the transmission of radiation in the samples at strong and weak laser radiation remains constant in a temperature range from -164 °С to+22°C.

We study the operating speed of high-speed photodetector based on GaSb/GaInAsSb/GaAlAsSb heterostructure with frontal bridge contact depending on the wavelength, radiation power, and bias voltage. The ultra-fast fiber lasers and high-speed oscilloscope were used for measurements.

Fluorescein and its halogenated derivatives representing a family of homologous dyes with the gradual substitution of halogen atoms for hydrogen ones are widely used in biomedicine as fluorescent probes. This stimulates the intense experimental and theoretical studies of their fluorescent properties in aqueous solutions. However, the theoretical calculations are complicated by the necessity of taking into account the effect of a solvent (water) in the explicit form and the need for effective basic sets. This is especially important for the dyes that contain heavy atoms. In this study, the quantum-chemical investigations of the dianionic form of fluorescein and its Br- and I-substituted derivatives (eosin Y and erythrosin B) have been carried out using the time-dependent density functional theory (B3LYP functional) implemented in the GAMESS software suite. The effect of a solvent has been considered in the framework of the modified Thomas polarizable continuum model. The calculations have been made for vertical (absorption and emission) excitations in the adiabatic approximation and at the nonequilibrium solvation. The results obtained for the nonequilibrium solvation are in excellent agreement with the experimental data for fluorescein and its halogenated derivatives.

The work discusses infrared photodetectors with quantum dots of germanium on silicon. The calculation of certain characteristics of detectors such as: dark current and detectivity in several modes: thermal generation mode, generation-recombination mode and background limited performance mode.

A wide range of rare earth doped crystals used as a lasing media includes: Y₃Al₅O₁₂ (YAG); Al₂O₃ (sapphire); chalcogenides of ZnS, ZnSe; sesquioxides of Y₂O₃, Sc₂O₃ and others. Ternary thiogallate compounds with common formula A^IIB₂³C₄ ⁶ (where A is: Ca, Sr, Ba; B is: Ga, Al; C is- S, Se, Te) consider as a perspective class of chalcogenide semiconductors revealing bright luminescence and laser oscillation properties when doped with rare-earth elements (Eu²⁺, Nd³⁺ , Ce³⁺ etc). In the present research, optical properties and observed laser oscillation of transparent ternary chalcogenide crystals of CaGa₂S₄ and CaGa₂Se₄ grown by the chemical vapor transport reaction and doped with Eu²⁺ (1.0-5.0 a t%) are described. The first observation of laser oscillation from a single crystal CaGa₂S₄ : Eu²⁺ (1.0-5.0 at%) have been reported earlier, and for CaGa₂Se₄ : Eu²⁺ it is reported for the first time in the present article. The life time of the excited state 4f⁶5d of Eu²⁺ ions in both crystals determined from the luminescence decay kinetics was ~3.8 μsec. It is shown that photoluminescence maximum in both crystals CaGa₂S₄ : Eu²⁺ and CaGa₂Se₄ : Eu²⁺ is due to the intra shell transition 4f⁶5d – 4f⁷(⁸S_7/2) ions.

Previously, was developed the method for calculating the light field inside a one-dimensional photonic crystal using perturbation theory by the value detuning from the band edge and calculating using this method the resonance properties of spectral transparency windows adjacent to band edge of a photonic crystal. The method allows to find the field when light propagates with frequencies lying near the band edge by using a set of eigenfunctions corresponding to the band edge for an infinite medium. The analytical expressions are obtained to describe this field and its characteristics, through these eigenfunctions. In the present work, the solution errors obtained by this method are investigated in comparison with direct computer-aided calculation of the field for a medium with a harmonic variation of the dielectric constant under various conditions for implementing this method. The problems of limiting the set of used spatial harmonics when calculating eigenfunctions (2 or more), limiting the number of eigenfunctions involved in constructing a solution (2 or more) are considered.

Features of compression of large-aperture negatively chirped amplified pulses of various aperture and durations up to a few-cycle in IR spectral regions are analyzed. Using the modified ray-tracing algorithm, the spectral-angular dependences of the radiation at different points of the beam cross section at the outputs of the grating compressors constructed according to the Offner, Martinez scheme and the scheme with a single-lens internal telescope are calculated. Offner compressor scheme has minimal aberrations and introduces a spectral angular chirp with a divergence much lower than the beam diffraction divergence. It was shown that in the region of 1.4 μm, negatively chirped pulses can be compressed down to near bandwidth limited duration of ~30 fs over the entire 40 mm beam aperture. It was also shown that, using stretchers with an internal telescope based on the Offner scheme, in the region of 3.6 μm it is possible to compress amplified negatively chirped pulses with duration of 40 ps and with a spectrum width close to an octave down to near bandwidth-limited duration of 18 fs duration at a 20 mm aperture.

Scheme for pulse compression during self-phase modulation in nonlinear media with a different sign of effective cubic nonlinearity is presented and investigated. It is shown that the proposed scheme is the most promising for implementing the regime of compression of powerful pulses to few-cycle ones in the spectral range of 1.55. In this case the maximum energy of compressed pulses is limited by the available aperture of nonlinear optical crystals. In the region of 1.55 μm, when using 5 mm BBO crystals, the achievable duration of compressed pulses is found to be 7.4 fs. The magnitude of the final nonlinear phase shift in the range of compressed beam intensities of 75-100% is more than an order of magnitude lower compared to multi-element spectral broadening schemes based on media with positive cubic nonlinearity. The proposed schemes can also be used to compress pulses in other spectral ranges with an appropriate selection of nonlinear optical crystals.

This paper is focused on the investigation of the effect of temperature on the laser amplification process. In case of Ybdoped active media there is a significant dependency of laser and physical properties on temperature that leads to reducing of gain coefficient. Theoretical description and experimental study carried out based on Yb:YAG crystal pumped by high power laser diode. Despite the cooling of the active element, the heating significantly affects at cwpumping regime and determines the shape of gain coefficient dependency on the pump power.

The results of experimental studies of filamentation of focused laser pulses of nanosecond megawatt duration in a medium with strong cubic nonlinearity are presented. It was shown that multiple small-scale beam self-focusing is observed, the nonlinear focus is much closer to the source than the geometric one, and this distance increases with an increase in the pulse energy (power). Long tracks are observed that are uncharacteristic of linear spatial focusing.

The results of experimental research of the filamentation of femtosecond laser pulses using a bimorph deformable mirror, which allows controlling the position of the filamentation domain determining localization of filaments and high-intensity channels in the beam cross section. The introduction of distortions into the amplitude profile of the beam with using masks showed the inability to control the number and position of filaments in the beam cross section.

In this paper, we have developed a chirped-pulse Er-doped all-fiber ultrashort pulse (USP) laser suitable for highresolution Raman distributed temperature sensor (RDTS) system application. Chirped-pulse regime which is determined by the positive net-cavity dispersion of +0.12 ps² allows us to increase the energy of the pulses for effective signal-to-noise ratio in receiving system. It also helps to avoid the influence most of nonlinear effects due to relatively long pulses duration of ~24.6 ps. The average power of the pulses is estimated to be ~1 mW from master oscillator, and currently increased up to ~15 mW by power amplifier. A relatively low repetition rate of ~ 7.925 MHz with signal-to-noise ratio ~ 69 dB was achieved using the resonator length of ~25.6 m. To characterize short-term stability of the obtained regime we have also measured the relative intensity noise of the laser, which is < -107 dBc/Hz in the range of 3 Hz - 1 000 kHz.

Airborne Light Detection and Ranging (LiDAR) can perform high-density scanning on the surface and quickly collect massive point cloud data with information such as three-dimensional (3D) coordinates and echo intensity. It is an important means of geospatial data acquisition and plays a very important role in various fields such as power inspection, forestry investigation, digital city, culture heritage protection, altitude hold and collision avoidance of Unmanned Aerial Vehicle (UAV), etc. Driven by the development of sensor technology and practical demand, airborne LiDAR has made great progress in hardware performance as well as industrial applications. This paper reviews the current status of the light and miniature UAV-borne LiDAR in China and other contries, then typical applications in related fields are listed. Finally, some future perspectives are presented.

In the Fresnel approximation, a laser beam with field phase random distortions is represented by the sum of diffraction-limited and scattered component. Analytical and semi-analytical relationships are obtained that approximate the flux radiation distribution function with a relative error of a few percent depending on the size of the receiver and its distance without limiting the amplitude and scale of field phase random distortions. It is accepted in the work that phase random distortions are distributed according to the normal law, are statistically homogeneous, and have a Gaussian correlation function. The axial intensity, radius of the beam and its caustic is studied depending on the phase distortions parameters. It is established that the phase distortions presence can lead to the appearance of a second maximum in the intensity distribution along the optical axis and a shift of the global maximum closer to the optical system output aperture. The research results can be used in the development of optical transmitters and adaptive optical systems, in tomographic studies of laser radiation, in the development of methods for measuring parameters and determining the optical quality of laser beams and optical systems.

The possibility of transformation of energy of fast and epithermal neutrons to energy of coherent photon radiation at the expense of a neutron pumping of the active medium formed by nucleus with long-living isomerous states is theoretically described. The channel of the nucleus formation in isomeric state as a daughter nucleus resulting from the nuclear reaction of neutron capture by a lighter nucleus is taken into consideration for the first time. The analysis of cross sections dependence of radiative neutron capture by the nuclei of gadolinium isotopes Gd¹⁵⁵ and Gd¹⁵⁶ is performed. As a result, it is stated that the speed of Gd¹⁵⁶ nuclei formation exceeds the speed of their “burnup” in the neutron flux. It is provided by a unique combination of absorbing properties of two isotopes of gadolinium Gd¹⁵⁵ and Gd¹⁵⁶ in both thermal and resonance regions of neutron energy. The possibility of excess energy accumulation in the participating medium created by the nuclei of the pair of gadolinium isotopes Gd¹⁵⁵ and Gd¹⁵⁶ due to formation and storage of nuclei in isomeric state at radiative neutron capture by the nuclei of the stable isotope with a smaller mass is shown. It is concluded that when the active medium created by gadolinium nuclei is pumped by neutrons with the flux density of the order of 10¹³ cm^-2·s^-1, the condition of levels population inversion can be achieved in a few tens of seconds. The wave length of the radiation generated by the medium is 0.0006 nm.

This paper presents the results of experimental research concerning the laser-plasma coating of steel substrate with the following powder grades: AP-FeCr4MnSiB (Fe_71.75C_4.81Cr_3.33Si_3.54B_14.10Mn_1.74V_0.73), AP-FeCr11Mn4SiB (Fe_66.8Mn_2.84C_2.85Si_5.3B_11.42Cr_10.79), AP-FeNi19Mn10SiB (Fe_56.12Ni_15.82C_1.65Si_4.92B_12.82Mn_8.66) and AP-G14 (Fe_29.4Ni_32.24C_5.32Cr_14.78Si_4.06B_10.22Mo_2.8W_1.16). As a focusing head was used self-made lateral nozzle for feeding powder. The nozzle was used in conjunction with scanning the laser radiation in the direction perpendicular to the movement of the focusing head. Coated tracks with various nozzle head movement speed (7-20 mm/s) was obtained. The elemental compositions of the resulting coatings were studied. Alloying elements are uniform distributed throughout the coating. During surfacing the powder particles are completely melted and partially mixed with the base material. This leads to increased iron content in the resulting coatings compared with the original powder. The hardness and thickness of the deposited layers were measured depending on the speed of the process. The hardness of the coatings is in the range of 7-12 GPa, the thickness is 0.15-0.7 mm. The wear resistance of the resulting coatings is up to 10 times higher than that of a steel substrate.

The intermediate results of the experiment on vortex laser beam synthesis based on coherent combining laser subbeams formed by a fiber collimators array are presented. The wave field results from interference of individual subbeams in this case and is determined by the phase relationships between them. A functional diagram of the experimental setup is given. The experimental results of synthesis of a laser beam with an orbital angular momentum are described. It is suggested to use a spiral phase plate to determine the sign of the topological charge of an optical vortex; the efficiency of this approach is estimated.

Scanning polarization lidar LOSA-M3 is designed to study of the optical characteristics of crystal clouds of the upper and middle layers at two wavelengths - 532 and 1064 nm. Lidar allows you to smoothly change the angle of inclination from the vertical with simultaneous conical (azimuthal) scanning. Such a measurement scheme makes it possible to study in detail the preferential orientation of ice crystals in the clouds. The lidar simultaneously measures the polarization characteristics of signals for linear and circular initial polarizations, which allows to obtain additional information about the anisotropy of scattering particles, including exploring the azimuthal orientation of the particles. The first results of observations of the crystalline cloud polarization structure carried out in Tomsk in April-October 2018 are presented in the article. The results show that the contribution of horizontally oriented particles giving a specular reflection can vary significantly in different parts of the cloud.

The efficiency of a real heat engines is considered. Basing on the entropy production minimum principle it is shown that the maximum efficiency of such a machine with an optimum power is n= 1-√T₂/T₁ defined by the root dependence of cooler and heater temperatures. This disappointing result was obtained earlier for the optimizing the power of Carnot cycle. In this paper we derive aforementioned expression from more general conditions. And we show that it is could be applicable to describe global changes in living and nonliving nature.

Presents the operation of a system for monitoring the process of laser processing of the surface of materials in real time, with a resolution of the order of several tens of nanoseconds, with a micron-scale spatial resolution designed to visualize laser-induced dynamic processes directly during laser processing of the surface of an object. The basic physical principles of its operation and the problems existing at the same time, as well as the prospects for overcoming them in various conditions of specific processes of laser thermal strengthening, including using computer simulation to search for optimal optical circuits and modes. The dynamic characteristics of the laser monitoring system are given.

Is analyzed composition and morphology of the nanostructures of vanadium oxides, synthesized by the ablation of pure metal in the distilled water. It is shown that the structures are folded of the amorphous material and have very high area of surface. These special features of the structures of vanadium nanooxides assume the prospect of their use as the substrates in the analytical method on the base of giant laser light RAMAN scattering (SERS).

In this work, luminescence of nanoparticles of zinc oxide synthesized in electric discharge in liquid media under the influence of intensive ultrasonic vibrations prior to cavitation and after the start of cavitation regime have been studied. The increase in the luminescence intensity of nanoparticles obtained by ultrasonic cavitation can be explained by the formation of defects in oxide crystals under the influence of intense mechanical action. In the process of synthesis, the particles are exposed not only to the action of electromagnetic fields, but also to shock waves during the collapse of cavitation bubbles, which leads to the formation of defective valence structures and delocalization of electrons. Plasma discharge in liquid under intensive ultrasonic field exhibiting peculiar characteristics has been demonstrated to be a powerful technique for obtaining zinc oxide nanoparticles with hexagonal shape and narrow particle size distribution.

In this work, a low-temperature plasma initiated in liquid media between electrodes has been shown to be able to decompose hydrogen containing organic molecules resulting in obtaining gaseous products with volume part of hydrogen higher than 90%. As feedstocks, organic compounds (alcohols, esters) as well as direct water-hydrogen emulsions obtained by ultrasonic treatment were used. It was shown that hydrogen productivity from emulsions is not less than that from individual substances. Optical spectroscopy was used to confirm the formation of atomic hydrogen in the reactions of plasma decomposition of liquids. The measurement of the amount of the gas mixture formed during the decomposition of organic liquids shows that the output is highly dependent on the discharge current, and also on the volume of the discharge, which can vary depending on the distance between the electrodes in the reaction chamber.

A complex physical and mathematical model of heat transfer in packages of flat cooled microdynamic gas- dynamic nozzles used for pumping gas-dynamic lasers is presented. A feature of such rocket nozzles is their small size (~ 15mm), so they quickly heat up, and therefore, an intensive heat sink is needed. The complex physical and mathematical model of heat and gas dynamics, heating and cooling is new, since all physical processes are interfaced at the boundary of a multiply connected region. The solution to the problem of cooling high-temperature gas-dynamic lasers is one of the main problems in their design. The results of a numerical solution are obtained for gas temperatures, heat transfer coefficient, cooler temperatures, and also for temperatures in the critical section of the nozzle.

In the present work, micrographs of polymer nanoparticles were studied by parameter image intensity to study their physical and chemical properties and the process of formation of polymer droplets. The use of digital image processing methods according to the parameter of the intensity of the image makes it possible to accurately determine the shape and size of particles, the dynamics of the polymer deposition process under study. In the study of dispersed systems of polymer nanodroplets, decoding by means of digital processing of microphotographs revealed the contours of the boundaries of the nanoparticles and the accompanying layer, calculated their area and estimated linear dimensions. Investigating changes in the intensity of the image of the layer of the polymer for various experimental conditions, allowed to reveal the principles of changes in density in this layer. Digital processing of photographs of particles of polymer by the criterion of intensity (brightness) of the image made it possible to obtain data on the parameters of nanoparticles, which are in good agreement with the results obtained using the instrumental methods of physical and chemical analysis.

In this work we fragmented of an aqueous suspension of a micron and submicron BSO particles sample via laser ablation. Also we carried out a comparative analysis of structure, phase composition, morphology, physicochemical and functional properties of materials before and after fragmentation. The results show that laser fragmentation leads to the formation of a homogeneous phase composition and better integration of bismuth in the bismuth silicate structure, as well as to an increase of photocatalytic properties of BSO during selective excitation in comparison with the initial material.

In this work, we study the effect of new iron oxide nanoparticles produced by the acoustoplasma method on the rate of formation of a fibrin gel in the enzymatic reaction of fibrinogen-thrombin. According to dynamic and static light scattering, we find that the addition of thrombin, preincubated with the nanoparticles (pH of the solution 7.5), to fibrinogen solution, accelerates the gelation reaction 30 times compared with the system without the addition of nanoparticles. Incubation of the nanoparticles with thrombin with decreased activity due to long storage leads to acceleration of the reaction in 4 times. The addition of thrombin, preincubated with the nanoparticles with less pH of the solution (5.5), to fibrinogen, in the opposite, slows down the reaction on the first stage of the process. During one hour after adding the thrombin-nanoparticles mixture to fibrinogen, the gelation reaction does not start. After this time, the reaction starts, but with the rate of 2 times less than without nanoparticles and 50 times less than with nanoparticles with pH 7.5. Such a difference in the biological effect of iron oxide nanoparticles on the rate of gelation under changing of their water environment pH is determined by the change in their surface charge (zeta-potential) and affinity for the thrombin enzyme.

The development of the electronic industry, with the further miniaturization of electronic components and the use of new materials puts forward increasingly stringent requirements for the quality, reliability and competitiveness of products. All this, in turn, dictates the creation of new technologies and technological processes. The microprocessing laser technologies at R&D production facility "Istok" named after Shokin " for the period 2003-2018, a series of modern automated laser technological installations of the "Caravel" type was created on the basis of industrial lasers and laser systems based on copper vapors and precision three-coordinate tables. This equipment with the diameter of the processing light spot of 10–20 μm and the peak power density of 10⁹-10¹¹ W/cm² allows for efficient and high quality processing of foil (0.01-0.2 mm) and thin-sheet (0.2-1 mm) metal and the large range of non-metallic materials of microwave products.

A comparative evaluation of the effectiveness of the Apadent Pro gel (Sangi, Japan) was performed on 15 extracted teeth in the patients aged 35 to 55 years. The teeth were divided into 5 equal groups. On the enamel of the removed permanent molars, the Apadent Pro gel was rubbed one time with an angled tip with a rubber nozzle in the first group for 10 s, in the second - 20 s, in the 3rd - 30 s, in the 4th - 50 s, in 5th - 60 s. The teeth were brushed twice a day in the morning and evening for 3 minutes. The calcium content in the surface layer of enamel was determined by the laser spectrometry (I 200 EC Applied spectra) before and after the rubbing of the Apadent Pro gel for 1, 2, 3, 6, 9, 14 days. It was found that the calcium content in the surface layer of enamel increases immediately after the rubbing of the gel in all teeth in proportion to the duration of treatment. The result remains high up to 3 days then decreases in the 1st and 2nd group and by day 14 decreases to the initial level. In the 3rd, 4th and 5th groups, the calcium content in the surface layer of enamel increases significantly, then gradually decreases. On the 14th day of observation, the caries resistance by the Ca/P coefficient is also estimated as high. According to the results of laser spectrometry, the optimal exposure time for the Apadent Pro gel on teeth is equal to 30 seconds. In the surface layer of enamel, the Ca content increases immediately after the rubbing of gel.

An experimental setup for precision processing of composite materials based on nanosecond pulsed and continuous ytterbium fiber lasers with a wavelength of 1.06 μm and a radiation power up to 1 kW with an optical scanning systems based on galvanic drives with a beam velocity of up to 17 m/s has been developed. The setup provides a power density in a focused light spot with a diameter of ≃100 μm using a continuous laser of 10⁷ W/cm² and a pulsed laser of 10⁹ W/cm², which is one order of magnitude higher than the threshold values necessary for removing carbon fiber in the evaporation mode. The focus depth of the focused radiation allows for high-quality processing of sheet blanks.

The results of comparative studies of laser cutting of glass are represented, which show that at high laser radiation powers it is possible to achieve the glass cutting speeds of 0.5 m/s or more. Such high speeds of laser cutting of glass with a thickness of more than 3 mm open up the possibility of using the modern powerful lasers in the glass industry.

In the present work prototype of laser gas analyzer of differential absorption technique on the basis of pulsed tunable Ce:LiCaAlF₆ laser is discussed. By means of wavelength tuning concentrations of NO₂, SO₂ and O₃ in the atmosphere of Kazan city were measured. The measured detection threshold appeared to be 2,52·10-6 g/m³ for NO₂, 0,30·10^-6 g/m³ for SO₂, 0,03·10^-6 g/m³ for O₃.

The review of experimental results concerning improving the tuning and energy properties of UV lasers based on crystals with the scheelite-type (LiY_1-xLu_xF₄) and colquiriite-type (LiCa_1-x Sr_xAlF₆) structures doped by Ce³⁺ and Cr³⁺ ions is presented. The negative effect of pump-induced photodynamic processes in active elements impact on the laser properties and approaches to minimize it are discussed.

The Bridgman technology details of growing up to 100 mm-length Cr³⁺:LiCaAlF₆ crystals are reported. The spectral-kinetic luminescence and laser properties for the pulse lamp-pumped laser are discussed.

Ensuring reliable functioning and stability of GNSS systems in any natural and man-made conditions is an urgent task. Understanding the physico-chemical processes developing in the atmosphere is important for successful solving these problems. The paper presents the results of the analysis of observations of atmospheric and ionospheric parameters during the development of storm meteorological disturbances in the Kaliningrad region. The data of observations of the atmosphere and ionosphere parameters were obtained using the methods of lidar sensing of the troposphere and vertical sensing of the ionosphere. Analysis of observations of atmospheric and ionospheric parameters showed that the development of such meteorological disturbances is accompanied by increased activity of wave processes in the troposphere with periods of 2-20 minutes. Perturbations with the same periods are observed in variations of ionospheric parameters. The obtained results indicate the correlation of dynamic processes in the lower atmosphere and ionosphere.

The use of a copper vapor laser (CVL) for the treatment of basal cell cancer (BCC) has allowed achieving highly effective elimination of BCC malignant cells without any recurrence for a long time after the procedure. According to recent translational medicine studies, the pathogenetic treatment of malignant skin diseases should include eliminating of not only pathological vascular bed, but also malignant melanocytes of the basal layer of the epidermis, promoting pathological development in the BCC involved area [1]. The targeted chromophore of melanocytes of the basal layer of the epidermis - melanin significantly differs in optical characteristics from the targeted chromophore of the vascular bed - oxyhemoglobin. Therefore, for the relevant pathogenetic laser treatment of BCC, it seems appropriate to use a dual-wavelengths laser exposure to CVL with wavelengths, one of which provides the high absorption by melanin (511 nm), and the other by oxyhemoglobin (578) nm. In this regard, it seems appropriate to use numerical modeling to analyze the effect of the relationship between the contribution of CVL radiation with a wavelength of 511 nm and a wavelength of 578 nm, taking into account the optical characteristics of the photoactive targets of the basal layer and blood in the pathological vascular bed of BCC.

It is well known that the processes of vertical propagation and dissipation of acoustic-gravity waves (AGWs) play an important role in the realization of connections between the dynamic processes in different layers of the atmosphere. This work presents the results of lidar probing of tropospheric aerosols, performed in Kaliningrad, Russia (54°N, 20 °E). The observations used a two-wave atmospheric lidar (with wavelengths of 532 and 1064 nm), which allows investigation of properties of troposphere up to the altitudes of 10-12 km. During the observations, the intensity of the lidar signal scattered in the troposphere was determined. Measurements that were carried out in the period of 2011–2018 that made it possible to determine the features of the vertical structure and the dynamics of aerosol particles. Analysis of the results of the observations revealed an increase of the wave activity in the troposphere during the periods of passage of the solar terminator in the range from 2 to 20 minutes.

The possibilities of using plasma formed by laser radiation in Ge- and Si semiconductors to create plasma antennas are analyzed. The dependences of the amplitude of the emitted microwave signal in the range of 6-7.5 GHz on the laser power and the length of the irradiated section on the semiconductor plate, which served as a transmitting vibrating antenna, were obtained. It is shown that the amplitude of the transmitted signal during the formation of a plasma antenna in Si and Ge crystals can be increased by more than an order of magnitude. The proposed method for creating a semiconductor plasma antenna with initiation by laser radiation has great prospects for creating materials with controlled electromagnetic characteristics in the radio, microwave and THz spectral ranges.

Aromaticity is one of fundamental characteristics of unsaturated organic molecules, which significantly determine chemical properties. By definition, aromatic molecules mast be cyclic, planar, have a complete conjugated π- electrons, and the number of π-electrons mast be 4n+2, where n is any integer number. Aromatic molecules are chemically very stable and have low reactive ability. In the contrary, anti-aromatic molecules, which have conjugated 4n π-electrons, highly unstable, preferably isomerize into aromatic composition, and demonstrate high chemical activity. In this paper, we study properties of typical aromatic and anti-aromatic compounds on the example of pentalene, phenylacetylene, and benzocyclobutadiene, and compare the change of their photochemical properties with changing the electric charge (under the single and double ionization). It was found that aromaticity of the molecules is really changing due to the loss of electrons. Dissociation reactions of pentalene, phenylacetylene and benzocyclobutadiene, as far as their cationic and dicationic forms were investigated. The effect of Coulomb repulsion in doubly ionized molecules also has been observed.

A method for bench testing of a sample of a reusable composite material when exposed to high-intensity thermal and ionizing radiation has been proposed. The tests were carried out on a specialized laser bench under the influence of high-intensity energy fluxes. As a result of the experiment, we obtained a field of temperatures and displacements on the surface and in the depth of the heat-shielding material at different points of time. The validity of the proposed mathematical model is confirmed by many numerical experiments. The results of some experiments are given as functions of time, temperature, the thermal characteristics, the mass and linear velocities of the pyrolysis zone, the density and stagnation pressure of gases in this area, and the pressure distribution and the mass filtration rate in the resulting porous residue.

ZnO:W luminescent material was prepared and characterized. We compare nano-sized and bulk material composition and luminescence. Nanoparticles were prepared by a novel acoustoplasma technique (plasma discharge in a liquid at an intensive ultrasonic field above the cavitation threshold). Bulk ZnO:W was prepared by classical annealing way from the mixture of ZnO powder and H2WO4. Under excitation with a pulsed electron beam, the ZnO:W nanoparticles demonstrated very low luminescence efficiency while the bulk sample produced intensive green cathodoluminescence. The most intensive green luminescence was observed after annealing of the sample in air, which excludes a well-known mechanism involving anion vacancies. Probably, tungsten impurity tunes excitonic luminescence towards longer wavelengths, but this point requires further investigations for verification.

The results of lidar measurements of emission spectra of targets and aerosols excited by filamented femtosecond Ti:Sapphire laser pulses are presented.

To optimize the welding processes and quality of a fixed connection needs to study of the melting and transfer of electrode metal into the weld pool. The paper discusses the results of studies of high speed processes of heat and mass transfer during arc welding with consumable electrodes. The imaging of such processes is difficult due to the presence of powerful light radiation from a welding arc. Its glow makes it practically impossible to obtain a satisfactory image using “simple” high-speed video recording methods. Our experimental researching has shown that the most effective method to improve the image quality of the studied object is the laser imaging method. It allows to significantly reduce the negative effects of background radiation. In the course of the research, the opportunity of using the CuBr laser with the narrow-band filters to image the observed object was shown.

The paper considers the possibility of determining the material of the object that caused damage to the turbine blade of the aircraft by optical methods with minimal impact on the blade. Experimental studies of the registration of emission spectra of residual quantities of duralumin and iron on a titanium substrate are presented. It is shown that the emission lines of these substances can be distinguished against the background of the substrate spectrum.

For long-term observations of the distribution of the tropospheric aerosol in Siberia, a year-round monitoring station for atmospheric parameters was established in Tomsk by lidar. The installation was carried out as part of Russian-French cooperation between the Institute of Atmospheric Optics and the LATMOS Laboratory (Sorbonne Universite) on the European project CNES EECLAT. For this purpose, the French company CIMEL Electronique manufactured the lidar CE372-NP according to the design of the LATMOS employees. Lidar belongs to the class of micro-pulse lidars operating at the same radiation wavelength. A diode laser at a wavelength of 808 nm is used as an emitter. The low pulse energy and the radiation wavelength of the semiconductor laser in the red region of the spectrum makes it work safe for the eyes. This makes it possible to fully automatically conduct continuous atmospheric sounding safe for others and to obtain long-term series of altitude profiles of backscattered radiation from the aerosol component of the lower troposphere. With the subsequent receipt of information on the height of the atmospheric boundary layer, restoration of its optical thickness and lidar ratio in combination with the CIMEL CE-318 photometer data. Lidar was installed at the "Fonovaya" Observatory of the IOA SB RAS, which is located in the background region of the Tomsk Region (56 ° 25 'N, 84 ° 04' E), from April 2015.

In the report the results of experiments on the registration of IR radiation backscattering from organic aerosol are presented and discussed. The studies were conducted on the bench for prototyping lidar measurements at a controlled optical way. Water aerosol and water aerosol containing organic components like tryptophan, alcohol, glycerin, and reduced nicotinamide adenine dinucleotide (NADH) served as model media. For these experiments we have modified the experimental set up under replacing UV laser on IR one -- a tunable waveguide CO2- laser. The IR photodetector MCT cooled by liquid nitrogen was used. As a result of the study, the ability to discriminate a number of aerosols among themselves by difference of the absorption spectra under CO2- laser wavelength tuning was demonstrated. It can be used in remote sensing of the different types of organic aerosols.

In this work, we study the interaction of new aluminum oxide nanoparticles produced by the acoustoplasma method with and without cavitation with blood plasma enzyme - thrombin. Using dynamic and static light scattering, we find that the interaction of thrombin with two types of nanoparticles leads to different ways of aggregation. In the case of interaction of thrombin with nanoparticles with cavitation, formed aggregates precipitate during several hours after mixing. In the case of the nanoparticles without cavitation, in the opposite, the stable aggregates are formed with a mean size of 700 nm. The total intensity of scattered light in the solution of thrombin with nanoparticles without cavitation increases 40 times one day after mixing with the maintaining of sizes. According to Rayleigh-Gans-Debye approximation, such an increase of the total intensity of scattered light may be caused by changing of either radius of particles or their concentrations, or refractive index of formed aggregates. Due to radius of particles formed remains unchanged, and to increase the concentration by 2 orders in magnitude, it is necessary the material intake (which is absent in the closed cuvette). Therefore, it is the refractive index of formed aggregates that change (Δn=0.3). Moreover, after the addition of thrombin-nanoparticle complexes to fibrinogen solution, the reaction of fibrin gel formation switched off. It testifies inactivation of thrombin under interaction with aluminum oxide nanoparticles (in opposite to the results obtained under the interaction of iron oxide nanoparticles).

The paper describes a developed sample of a mobile (helicopter) laser spectroscopic system, provides diagrams, and presents discussion of the results of experimental studies of fluorescence and Raman spectra of model objects, simulating the presence of heavy hydrocarbons in various concentrations.

Experiments were carried out on model objects to study the fluorescence and Raman spectra, simulating the presence of heavy hydrocarbons in various concentrations. The use of several sensing wavelengths and a wide spectrum of recording wavelengths potentially makes it possible to identify the yield of such hydrocarbons, which create a concentration of saturated vapors of 0.02-10 ppm at a temperature of 20± 5 °С.

Pulsed laser ablation is at the basis of the processes of laser processing of materials and is used in high-tech production. A feature of laser ablation is the probabilistic nature of ablation destruction processes, which is due to the random spatial distribution of absorbing defects and their characteristics. This results in different laser breakdown threshold values, probabilistic development of laser plasma formation, and a strong relationship between the destruction threshold and the size of the laser radiation interaction region (dimensional effect). The authors carried out studies of laser ablation destruction of polymer materials. The samples were hafnium dioxide films on the silicon surface. The test materials were exposed to a pulse radiation Nd₃₊:YAG laser to measure the threshold energy density of the laser ablation and to relate the obtained values to the known properties of the nanocomposites.

The features of the formation of a barrier discharge in xenon (p = 300 Torr) depending on the frequency of the pulses of the applied voltage were studied in this work. It was found that the discharge in the frequency range f = 1–40 kHz has three modes: 1) visually homogeneous low-power mode at f = 1–4 kHz, 2) channel mode at f≈5 kHz, and uniform powerful one at f> 5 kHz. Dependences of current and voltage on time indicate that at f ≤5 kHz the discharge is initiated due to streamer and at f> 5 kHz due to the Townsend breakdown mechanisms. The transition from a low-power to a channel mode can be explained by thermal constriction: the gas temperature gradient and spatial heterogeneity of the electron production increase with frequency growth, aggravated by the death of electrons during dissociative recombination. The transition from a channel mode to a homogeneous powerful one can be explained by an increase in stepwise ionization, which reduces the spatial inhomogeneity of electron production. In argon and krypton discharges of a similar design in the frequency range f = 1–40 kHz, only a uniform powerful mode, initiated by the Townsend breakdown mechanism, was observed. This can be explained by lower values of the dissociative recombination rates in Ar and Kr in comparison with Xe and larger values of electron diffusion coefficients. In the VUV emission spectrum of the Xe discharge a band was observed with a maximum at λ= 173 nm. The intensity of the band linearly increased from 1 to 30 mW/cm² in the range f = 1–40 kHz. In the UV region a low intensity continuum with a maximum at λ = 270 nm was observed. In the visible region, Xe atomic lines were recorded in the area λ = 440-500 nm, which appear as a result of dissociative recombination of the Xe₂⁺ ion.

The kinetic (0-dimensional) model of a pulsed-periodic discharge in mixtures of argon with sulfur vapor, based on solution of the balance equations for plasma species and the electron energy balance equation was developed. The discharge is an effective source of radiation with spectrum, similar to solar spectrum in the wavelength range of 280-600 nm (B³Σ→X³Σ - transition of S₂). Variation of plasma species densities during a voltage pulse for various Ar-S₂ mixture compositions at different values of the reduced electric field (E/n) under gas pressure ~40 Torr was studied. It is shown, that a breaking field E/n, at which a transition from electronegative to electropositive plasma takes place, increases with sulfur fraction in Ar-S₂ mixture. Ar-S₂ plasma as simulations show is electronegative; the primary positive ions in Ar-S₂ plasma are S₂⁺ and Ar⁺ ions, the primary negative ions are S₂^- and S^-ions. It is found that during the voltage pulse density of S₂ * (B ³Σ ) molecules fast rises and exceeds densities of other excited species; however, when the voltage pulse decreases and, as a consequence, energy of electrons diminishes, density of excited sulfur molecules prompt falls while density of resonance excited argon atoms decreases very slowly. This is a reason for appearance of Ar lines along with S₂ bands in spectra of the pulsed-periodic discharge in sulfur vapor argon mixtures.

Thermal cracks in LTB:Cu luminescent ceramics are connected with the presence of air voids in the material, which decreases the heat conductance. Powder phosphor would be more stable against heat. The effects of sintering time, grinding, and subsequent annealing on the luminescence intensity are studied. Rough grinding decreases the efficiency by 15-20%, but this should be checked more thoroughly. Subsequent annealing does not affect the luminescence properties if the annealing temperature does not exceed 400 °C, but the luminescence yield decreases if the temperature exceeds 500 °C. Due to a large number of luminescence centers and a relatively small amount of electron traps, LTB:Cu should be tolerant of high radiation doses caused by bombardment with electrons in cathodoluminescent UV-radiation sources.

The paper demonstrates the possibility of studying blue jets in laboratory apokamp discharges as a source of blue streamers that move upward from the discharge channel. Research data are presented on the formation of such streamers in low-pressure air at a voltage of tens of kilovolts, showing for the first time that they do arise at low (∼8 Hz) pulse repetition frequencies under pressures at which gigantic blue jets develop 10–20 km above the Earth. At a voltage of positive polarity with an amplitude of 33 kV, the streamer velocity in a pulsed apokamp discharge reaches 560 km/s. When applying microsecond voltage pulses of amplitude 15 kV with a repetition frequency of 50 kHz, the length of streamers ranges to more than 120 cm.

Now, agriculture strives for advanced technologies that would speed up the seed germination, reduce the plant disease incidence, and enhance the crop yield. In this connection, more and more studies address ultraviolet irradiation of seeds and plants as a way to increase their sowing quality. In this paper, XeCl-excilamp (λ~ 300-320 nm) ‒ as a simulator of solar short-wave radiation ‒ is used in the quality of source of ultraviolet radiation. A new data on morphometric and morphological indicators of development of a number of economically valuable crops (parsley, cucumber, pumpkin, zucchini) exposed to XeCl-excilamp are presented. In particular, it is shown that the ultraviolet treatment increases the number of zucchini fruits ("Tsukesha" sort) by an average of 40%, compared to untreated control samples and increases the area of the assimilating surface of leafs (in the first week after germination and further in a month and two months) by an average of one and a half times. Compared with the control 90-second treatment of seeds zucchini led to a higher content of vitamin C in fruits and more than a twofold reduction of nitrate to 64±7 mg/kg. Similar results were obtained for the pumpkins. First processing radiation of XeCl-excilamp were subjected parsley seeds. Found processing conditions in which you can increase the yield by an average of 20%. The obtained indicators allow us to draw a conclusion about the economic feasibility of XeCl-excilamp seeds illumination and confirm our conclusions about the prospects of such a procedure for pre-sowing plant seeds.

A new models of Xe₂-excilamp (with maximum of radiation spectra at 172 nm) developed in Optical Radiation Laboratory of High Current Electronics Institute are presented. The task of creating a lamp with the most simple design embodiment was solved. The bulb of such an excilamp was made from a single quartz tube with a diameter of 22 mm and a length of 12 cm. The length of the discharge region was 4 cm. The lamp was supplied with voltage pulses from a generator of 2 μs with a repetition frequency up to 100 kHz. A radiant exitance of 3.5 mW/cm² has been obtained. This value has not changed after 2400 hours of excilamp operation. The report will also describe other designs of Xe₂-excilamps.

GaSe-type crystals have attracted increasing attention because of pronounced structural anisotropy, unique optical and Nonlinear Optical Properties, which may lead to numerous applications in light generation (second harmonics and tuning in a wide transparency range of λ= 1÷20 μm) and optoelectronics (radiation detectors, photovoltaic energy converters, photo-resistors, light modulators etc.). In the present work, damage threshold of the Bridgman grown GaSe and its structural analogs ((GaSe_1-x S_x (where 0 ≤x ≤0.25, InSe and GaTe)), have been investigated under IR τ = 5 ns pulses (λ= 1.064 μm) of "QUANTELL Brilliant b" laser (pulse energy ~ 850 mJ, f = 20 Hz). For all studied crystals occurrence of local micro defects and pulse induced heating were identified to be responsible for damage threshold mechanism. Results for GaSe obtained in the present work are in good agreement with published in literature for damage threshold excited with laser lines in the spectral range of λ= 1.1 ÷ 2.9 μm lines of the Optical Parametric Generator. The values of damage threshold for solid solutions of GaSe_1-x S_x, InSe and GaTe crystals are reported for the first time.

We present a detailed study of the dielectric constant and loss tangent of popular nonlinear optical crystals LBO, β-BBO, and KTP in the range of 0.6-1.5 mm (200-500 GHz) at room and liquid nitrogen (77 K) temperatures. These materials have a strong commercial influence as nonlinear frequency converters of laser radiation in the visible and near-infrared spectra, but the prospects for millimeter-wave photonics and optoelectronics applications are still unclear. Besides, the phase-matching curves for DFG of 1.064 μm laser radiation into millimeter waves were numerically estimated to show the feasibility of using the crystals as compact intense radiation sources.

The paper presents the results of experimental and theoretical studies of the role of avalanche ionization in the process of highly nonlinear generation of electron-hole pairs in the interaction of intense femtosecond laser radiation with dosimetric crystals LiF:Mg,Ti. We assume that the effective formation of defects of hole-interstitial type, which consist of molecular halogen ions placed in one cationic and two anionic vacancies, distinguished by high-temperature peaks in the thermally stimulated luminescence curves, is feasibly connected with avalanche ionization processes occurring in the regions of passage of light filaments. The calculated dependences of the plasma density on time during the laser pulse made with taking into account the avalanche ionization for this type of crystals show that the contribution of avalanche ionization to the electron-hole plasma density is comparable to that of the multiphoton tunneling mechanism.

THz generation experimental results in a filament plasma produced by focusing ultrashort Ti:Sapphire laser pulses at a wavelength of 950 nm are reported. A study of structure and time-resolved dynamics of forming the laser filament is carried out. THz radiation dependence from filament length and pump energy is also given. Optimal conditions for efficient THz generating were found.

This paper presents model study and experimental results on frequency conversion of Ti:Sapphire laser operating at 950 nm into the long-wavelength THz range in a β-BBO crystal. The generating spectrum in the range of 0.2 - 0.8 THz is studied in detail.

Emission of THz radiation from a single-color ultraviolet (248 nm) and infrared (744 nm) filament in air is studied experimentally and compared at similar pulse durations, focusing conditions and excess of peak pulse power over the critical power for self-focusing. An angular distribution of the terahertz emission for both ultraviolet and infrared pump is conical with the closed cone angle. In contrast, the terahertz radiation energy and spectrum differ significantly. The energy of terahertz emission from ultraviolet filament is 1-2 orders of magnitude lower than the terahertz yield from the infrared filament. The terahertz spectrum of ultraviolet filament is shifted to the low-frequency range and narrower as compared to the spectrum of terahertz emission from infrared filament. We explain qualitatively the difference in terahertz yields and spectra by lower intensity and plasma density in the ultraviolet filament. Similar behavior of THz spectra is observed when changing the IR filament parameters.

An experimental investigation of the detection of optical laser radiation in a magnetized transparent ferromagnet, at room temperature was made. As a source of electromagnetic radiation in the optical region we used Spectra-Physics Mai-Tai femtosecond laser with a wavelength tuning range from 710 nm to 950 nm. The laser radiation was linearly polarized, and the peak power was about 300 kW. For the detection of laser pulses a monocrystalline ferromagnet YIG was used, which is partially transparent in the laser tuning region. It is established that the detection is due to the nonlinearity of the static magnetization curve. To determine the dependence of the degree of correlation between the magnetization curve and the amplitude of the detected signal, on the external magnetic field, the detection process was modeled in Matlab. The comparison shows that the results of measurements and simulations correlate well with each other, and the magnitude and sign of the detected signal correspond to the curves of static magnetization.

An active waveguide-antenna in which the nonlinear crystal is the source of THz radiation is considered. The coherent terahertz radiation generated via optical rectification of 100 fs pulses of a Ti: sapphire laser in a system of a “nonlinear optical crystal partially filling the cross section of a metal rectangular waveguide” is investigated. It is shown that the fulfillment of the phase-matching condition and the optimization of the characteristics of radiation transmission through the integrated system “nonlinear crystal + waveguide” affect the efficiency of generation of THz radiation.

Stimulated Rayleigh–Mie scattering (SRMS) in two-photon absorption liquids is realized by a Fourier transform-limited pulsed Nd-glass laser. For the first time, we have measured anti-Stokes spectral shifts of SRMS in toluene and hexane colloids of Ag nanoparticles, as well as in pure toluene. The suspensions are prepared in the plasma discharge excited in a liquid exposed to an intense ultrasonic field above the cavitation threshold. This novel technique has been developed for the synthesis of various nano-sized materials; it provides silver nanoparticles suspensions with controlled narrow distribution of the particle size. Ultrasonic cavitation results in a drastic change in the physical properties of the liquid, providing specific conditions in the electrical discharge plasma. Ag nanoparticles with 1-2 nm radii in toluene and hexane are obtained from silver electrodes under these specific conditions and acquire unique surface characteristics which prevent them from secondary agglomeration. The values of anti-Stokes spectral shifts of SRMS appreciably exceed the Rayleigh line width in those liquids. The four-wave mixing method is applied both experimentally and theoretically to display the process as Rayleigh-induced parametric generation. We show that the amplification effect is provided predominantly by thermally induced coherent polarization oscillations, while an interference-assisted thermal grating provides formation of a self-induced optical cavity inside the interaction region.

Stimulated low-frequency Raman scattering (SLFRS) spectrum in dimethylformamide (DMF) was registered in the range from 0.1 to 1 cm-1. SLFRS is a result of the laser pulses interaction with acoustic oscillations of the associates, therefore knowledge of the SLFRS frequency shifts (and consequently associates eigenvibrations frequencies) gives possibility to estimate the size of DMF associates. Scattering was excited by pulses of a ruby laser with a narrow spectral line and recorded by Fabri-Perot interferometers. In the scattering spectrum SLFRS component was recorded with a frequency shift of 0.33 cm–1 (10 GHz), which corresponds to the size of associates of about 150 nm. Simultaneously with the SLFRS, stimulated Brillouin scattering was recorded in the backward scattering spectrum.

The changes in the stiffness modulus of collagen structures in a collagen phantom were studied using optical coherent elastography (OCE). The disorganization of the phantom collagen fibers was obtained by mechanical action (twisting). Young's modulus values were measured for various phantom density values using the compression OCE method.

The of multiphoton microscopy (MPM) based on two-photon fluorescence and second-harmonic generation is promising for diagnosing neoplastic transformation of tissues. The results of MPM studies of tissues with prostate adenocarcinoma embedded in paraffin blocks are presented. The tissue fluorescence was also analyzed using the fluorescence lifetime (Fluorescence-lifetime imaging microscopy - FLIM) option. The relationships between the fluorescence peculiarities and the second harmonic generation of the prostate gland tissues were obtained for different morphological images.

With the increase of microalgae biomass cultivation opportunities, kinetic modeling of microalgae photosynthesis and growth has become more significant, because precise model is an enabler for creation of effective photobioreactor, prediction of process productivity and improvement of operation environment. Light is major factor, affecting the kinetics of microalgae photosynthesis. In this case, light intensity and spectral structure are the most important characters. Under lacking light conditions photosynthesis in cells decelerates, and optical density of suspension decreases. Moreover, redundant density of photonic flux causes photoinhibition in cells, what leads to reduction of optical density of microalgae suspension. This means that optimum illumination plays vital part as well as temperature, nutritional medium, and CO₂ delivery.

Confocal laser scanning microscopy and electrochemical analysis were used to estimate the effectiveness of four blocking agents for biosensors preparation. The surface biomolecules layer was visualized. Among blocking agents under study, casein was chosen as the most suitable for electrochemical biosensors development.

The contribution of the indirect mechanism to the inactivation of microorganisms by long wavelength VUV radiation (λ>170 nm) was investigated in this work. For these purposes dry spores of microscopic fungi Rhodotorula colostri and Saccharomyces cerevisiae were irradiated by Xe excilamp (λ= 173 nm).To determine the contribution of indirect action to the microfungi inactivation, the survival probabilities of the samples grown on a nutrient medium containing antioxidant (I₂) and without it were carried out. The results have shown, that the survival probabilities of the spores containing antioxidant increases by no less than 20-25% compared to control ones. The increase value depends on VUV irradiation dose and microorganism type. It should be emphasized, that due to the masking of microfungi survival by I₂ bactericidal action, the obtained survival probability increase values should be considered as a lower estimate. Electrophoresis of microfungi DNA have shown, that VUV irradiation of spores containing antioxidants leads to less DNA destruction and heaver DNA fragments appearance. The latter may indicate a decrease of reactive oxygen species effect on DNA in the presence of antioxidants. Atomic force microscopy and IR spectroscopy haven’t shown influence of antioxidant on cell wall destruction. This can indicate, that in contrast to wet spores, in the case of VUV irradiation of dry ones, the indirect mechanism of cell wall destruction is absent or weakly expressed.

This paper studies the influence of photoactivation on the antibacterial activity of nanoparticles (NPs) obtained by pulsed laser ablation (PLA) of a brass target. The initial composition of the target is presented by a cubic phase is Cu₆₅Zn₃₅/Cu₅₀Zn₅₀. PLA in water was found to produce Cu₂O and ZnO NPs. Generation of a different phase of brass (Cu₈₅Zn₁₅) was also observed. A number of studies was conducted to test the antibacterial properties of cotton treated with colloidal solution. Strain of S.aureus bacteria was used to evaluate antibacterial activity of prepared NPs, and it turned out to be high enough; an additional exposure of red light (610 nm) did not induce any changes in the antibacterial activity of the samples. Irradiation of the "soft" ultraviolet (365 nm) led to a sharp spike of the antibacterial activity an d complete death of bacteria.

Low-level laser exposure is a non-invasive and less painful method, which is used as an alternative method to classical acupuncture with metal needles and could be applied in clinical medical practice. The study of the laser acupuncture effect on the electroencephalogram (EEG) characteristics was carried out. The electrodes were located on the surface of the subject's head according to the standard scheme 10-20. Experimental EEG data were obtained by standard digital 16-channel electroencephalograph with EEG18 V5.0.3 software. The EEG frequencies in each of the measurements have been analyzed. This work shows that low-level laser stimulation able to change the power of rhythms in the head areas, which corresponds to the stimulation of different brain regions.

The paper presents the results of studies of the effect of single presowing treatment of wheat seeds with XeCl excilamp radiation at 308 nm with various surface irradiation doses on the yield and seed quality of spring wheat of the Iren variety, obtained in 2018 in the Tomsk.

Currently, there is a widespread occurrence of breast cancer. Long-term radical mastectomy can lead to the development of lymphedema. Finding intraoperatively unaffected lymph nodes, and therefore their preservation, could prevent the development of lymphedema. The authors describe the hardware of the device of extended photodynamic visualization for differentiation of the lymphatic pathways of closely located organs. This devices allows to work with two dyes (methylene blue and indocyanine green) at once. The article also presents studies proving the efficiency of the methodology.

Cumulation effect of a beam of runaway electrons formed in a high-voltage nanosecond discharge in air at pressures of 3-10⁵ Pa and discharge gap length d of 1 - 5 mm was studied. Optimal conditions of the effect in discharge gap with a tubular potential cathode and grounded flat anode was achieved at an air pressure of ~ 5 Pa and d of 2.7 mm. An electron beam current pulse was recorded behind a foil anode with high (up to ~ 80 ps) time resolution. It was found that, due to the cumulation effect, a through hole is formed in an aluminum foil 20 μm thick after 2-3 discharge pulses. The electron beam was found to register around the zone of maximum beam current density as well. As follows

Discharge and laser parameters in high-pressure gas mixtures of rare gases with F₂ under pumping by generators with inductive energy storage (IES) and semiconductor opening switch (SOS) are studied. It was shown that the pre-pulse with high pumping power formed by IES produces high-density discharge plasma and inversion population in gas mixtures under study within ∼10 ns and provides both early one-set of lasing and conditions for efficient excitation of an active medium from the storage capacitor. The high-voltage pre-pulse from the IES and sharp increase of discharge current allows to form long-lived stable volume discharge. Improve of pulse duration and (or) output energy was achieved for atomic fluorine, ArF* and KrF* excimer lasers.

The electrothermal Arcjet are used in spacecraft orientation systems. A design feature of the Arcjet chamber is an enclosed volume containing a plasma streamlined by a stream of cold gas. The methods of emission spectroscopy make it possible to estimate the kinetic parameters of the working gas of the engine, the emission of electrodes, the velocity of the gas jet, and, in some cases, the concentration of the components. One of the most important parameters is the components temperature of the plasma gas forming. The temperature of the argon working gas in the Arcjet chamber was found in the approximation of partial local thermal equilibrium. The temperature value made it possible to determine the effective argon flow rate and the corresponding speed of sound and made it possible to explain the experimental results of the found oscillation frequency of the arc voltage of the discharge chamber in the Helmholtz resonator mode near f_H = 6.25 kHz. It is shown that the length of the discharge chamber in the approximation of a partially-open resonator can be decisive when finding the resonator's own oscillations.

The paper presents measurement data on the radiation excited in synthetic diamonds, leucosapphire, and quartz KU1 at a wavelength of 200–800 nm by a pulsed electron beam with an energy of up to 400 keV. The crystals reveal wide bands whose intensity increases with decreasing wavelength in the range 220–400 nm. For leucosapphire and quartz, the radiation pulse at these wavelengths is close in duration to the electron beam current pulse, suggesting that it is Cherenkov radiation. For synthetic diamonds, both Cherenkov radiation and pulsed cathodoluminescence are detected in this spectral region. In particular, an intense band of free excitons with its maximum at 235 nm is found at high beam current densities and electron energies.

The objective of the work is to study effect of the rise time of voltage pulses ranged from 15 ns to 1.5 μs on generation of runaway electron beams and X-ray radiation in nonuniform electric field. Three setups and different pressures of air, nitrogen, argon and helium were used. The experiments on the setup #1 have confirm that there are different regimes of generation of runaway electrons and X-ray emission when voltage pulses with a long front duration are used. When voltage pulse amplitude reached 150 kV at a pulse rise time of 1.5 μs, the new results was obtained on the setup #3. At this setup, a runaway electron beam was registered by a collector in argon, air, and nitrogen at pressures up to ≈ 12.5 kPa. When using helium, a supershort avalanches electron beam (SAEB) was obtained at a pressure of 100 kPa.

The effect of modification of the MFI zeolites by ZnO and activated by diffuse discharge plasma generated in ambient air on acidic and catalytic properties in conversion of propane-butane fraction into arenes has been considered. Plasma activation of zeolite modified with 3% ZnO leads to a significant increase in catalyst activity. The maximum yield of arenes is observed on zeolite catalysts modified with 3% ZnO and activated by plasma, and is 64.9% at 600°C, which is 12% more than on the original zeolite. The activity of zeolite catalysts modified by ZnO and activated by plasma corresponds to their acidic properties.

Results in the field of Raman spectroscopy of diamonds are demonstrated. Some of them have or might have important practical applications.