The development of effective discharge pulse-repetition KrF laser is informed. Research the possibility of forming in this laser long laser pulse with input pump energy for a few half periods of the discharge current are presented. In the repetitively pulsed regime (up to 100 Hz) laser provides laser pulses with energy of 1 J and duration of 60 ns at the base. The maximum total efficiency of the laser is 3%. The results of studies on the formation in this laser of narrowband radiation with a wide spectral band tuning are reported. The possibility of forming a radiation pulse with a linewidth 2 pm, energy 0.15 J and spectral tuning region 247.5-249.6 nm are demonstrated.

We have detected the separation of generation in active medium of XeCl-laser when the formed beam part was returned back to active medium. We have obtained the anomalous intensity distribution along the cross-section of output in the resonator configurations forming the constrictions between the mirrors. Evidently, we first observed the laser field self-action through the emissivity of particles of the active medium.

Formation features of run-away electron preionized diffuse discharge (REP DD) and REP DD properties in different experimental conditions are studied. It was shown that sufficient uniformity of REP DD allows its application as an excitation source of lasers on different gas mixtures at elevated pressure. Promising results of REP DD application for development of gas lasers are shown. Stimulated radiation in the IR, visible and UV spectral ranges was obtained in the diffuse discharge. Ultimate efficiency of non-chain HF(DF) chemical and nitrogen lasers on mixtures of SF₆ with H₂(D₂) and N₂ was achieved. New operation mode of nitrogen laser is demonstrated under REP DD excitation. Kinetic model of the REP DD in mixtures of nitrogen with SF₆ is developed allowing to predict the radiation parameters of nitrogen laser at λ = 337,1 nm. Long-pulse operation of rare gas halide lasers was achieved.

This paper reports on first experimental study of a self-sustained volume discharge (SSVD) in c-C₄F₈. The discharge voltage and current oscillograms are taken over a wide range of gas pressures. How and why this discharge radically differs from that in other strongly electronegative gases is considered in terms of the theory of the vibrational relaxation in polyatomic molecules. For the first time an SSVD in c-C₄F₈ preheated by CO₂-laser radiation has been investigated. The unusual behavior and temperature-dependent characteristics of this discharge are revealed. There is much discussion on the peculiarities of an SSVD in a preirradiated c-C₄F₈. To refine the static limiting field in c-C₄F₈ the static dielectric strength of c-C₄F₈ is measured on changing the gas pressure by nearly two orders of magnitude.

The results of a comparative study of CuBr-laser energy characteristics with a small active volume operating in pulse-periodic mode and dual pump pulses are presented. The advantages of these regimes in the range 5-100 Hz and 5- 100 kHz for output power, the energy generation and efficiency of the laser are shown.

The structure of intermetallic clusters Au₁₂M (M=Hf, Ta, W, Re, Os) and features of their interaction with electron donors and acceptor atoms, i.e. H and F, were investigated making use computer calculation based of density functional theory. In was found that metal clusters with effective electron number equal to 18 have more symmetrical shape then that with a number of electrons differing from 18. The interaction of gold nanoparticles with silica was modeled by attachment of SiO₄H groups and the connection of the electronic structure with electronic transitions in spaser is discussed.

Results of 2D simulation of a KrF laser are presented. In the model, inhomogeneities of distributions of the electric field and plasma particle concentration are considered. It is demonstrated, that the laser energy depends not only on the value of the total pump power, but also from its spatial distribution. The shape of the electrodes is a major determinant of the spatial distribution of pumping power in the active medium. For electrodes with small radii of curvature, the pumping power in the center of the discharge may be too high. This leads to the suppression of radiation in the center of the discharge and the limitation of the laser energy.

Results of investigation and development of an excitation pulse generator with magnetic pulse compression by saturation chokes for pumping of active media of CuBr, Sr, and Ca vapor lasers are presented. A high-power IGBT transistor is used as a commutator. The generator can operate at excitation pulse repetition frequencies up to 20 kHz. The total average power for all laser lines of the CuBr laser pumped by this generator is ~6.0 W; it is ~1.3–1.7 W for the Sr and Ca lasers.

Processes of inversion creation in a number of barium and europium atomic transitions under pumping of vapors by eximer XeCl* and KrF* lasers have been investigated. Qualitative study of inversion creation mechanisms that are common for barium and europium atoms has been carried out. Necessary conditions for observation of atom lines of Ba and Eu amplified spontaneous emission (ASE) have been formulated. It has been found that observed absence of long-wave satellites of Eu resonant lines is caused by ASE absence in atomic transitions 8p⁸P_9/2 → 6d⁸D⁰_7/2 and 8p⁸P_9/2 → 6d⁸D⁰_11/2 of europium atom. Whereas, absence of ASE in transitions 8p⁸P_9/2 → 6d⁸D⁰_7/2 and 8p⁸P_9/2 → 6d⁸D⁰_11/2 of Eu atom is a result of high offset, or starting of pre-dissociating pumping channel of 6d⁸D⁰_7/2,11/2 Eu levels. Problems, caused by of undetermined nature of resonant emission that is observed under optical pumping of europium and barium vapor, are discussed in this paper.

Merocyanine 540 (M540) is famous dye that used in electronics and medicine. An important feature of the dye is a significant intramolecular transfer of the electron density in the excited state. Experimentally was investigated the electronic absorption and fluorescence spectra in different solvents M540. Electronic structure, spectra and rate constants of photo-physical processes of an isolated molecule and its complexes with water molecules were calculated by INDO method with spectroscopic parameterization. Analysis of the results allowed establishing the effect of individual fragments and hydrogen bonds with water on the electronic charge transfer between the terminal units in the state S₁. Examination of photo-physical processes of decomposition of the fluorescent state was showed that the intramolecular processes of decay of the S₁ state are not the cause of the differences calculated and experimental fluorescence quantum yield. Consideration of trans-cis photoisomerization leads to the elimination of this non-compliance.

The influence of thermolysis time on the absorption spectra of partially thermally dehydrochlorinated polyvinyl chloride in acetophenone solution is studied. Strong increase in the optical density D_λ of the dehydrochlorinated PVC samples is caused by the increasing amount N_-C=С- and the length of chains of conjugated double bonds of carbon -C = C-. It is noted that the optical density D_λ first increases linearly with dehydrochlorination time and then reaches saturation. The estimation of amount of double conjugated carbon bonds in 1ml versus thermolysis time t is given, which varies between N_-С=С- = 4·10¹⁷ – 7.4·10¹⁸ for t from 40 to 420 minutes. The effective capture cross section of a photon on conjugated double bonds of carbon for dehydrochlorinated PVC solution in acetophenone is estimated, which was about 10^-17 cm² . The analysis is done of the absorption curves «red» shift to longer wavelengths with growth of N_-С=С- upon increase of thermolysis time. It is noted that the dependence of the optical density on the wavelength in this range is well described by a simple exponential function.

The effect of sediment flotation was observed in dispersion of graphene oxide flakes with Ag-particles deposited thereon in the aqueous-organic (containing dimethylformamide) under the visible light action, with subsequent stabilization of the dispersion, which does not occur in the absence of Ag-particles. The main reason for this laser light induced movement of sediment graphene oxide flakes may be associated with the appearance of small bubbles. The further development of this approach seem to be able to estimate the of graphene flakes photoactivity with different activating particles.

Dissolved organic matter plays an important role in pollution migration from human waste to aquatic environments. In this study, the effect of humic acid (HA) on the photo-chemical transformation of naphthalene by irradiation model solar and UV light was reported using fluorescence quenching titrations. It was calculated the interactions between naphthalene and humic acids. It is found that the molecular complex of humic acid and naphthalene is more stable to UV irradiation, compared with the model solar radiation. The application of molecular fluorescence spectrometry is a useful sensitive tool evaluate intermolecular HA and naphthalene interactions.

The paper describes an analysis of possible ways of deactivation of electronically excited states of 4-hydroxy- 3-methoxy-benzoic acid (vanillic acid) and its protolytic forms with the use of quantum-chemical methods INDO/S (intermediate neglect of differential overlap with a spectroscopic parameterization) and MEP (molecular electrostatic potential). The ratio of radiative and non-radiative deactivation channels of the electronic excitation energy is established. The rate constants of photophysical processes (internal and intercombination conversions) occurring after the absorption of light in these forms are evaluated.

Results of experiments on controlling the position and length of the filamentation zone of femtosecond laser pulses in atmospheric path length 150 m using different initial spatial focusing and defocusing. The obtained distribution of filaments along the filamentation zone, measured dependence the length of the filamentation zone of the numerical aperture of the beam, its initial radius and pulse power.

The results of experiments to study the spatial characteristics of multiple filamentation gigawatt laser pulses in the glass are presented. It is shown that with increasing pulse power multiple filamentation region increases in length and diameter, the distribution of filaments within the region has a maximum value when the power > 105 Pcr area filamentation takes the form of a hollow cone, the apex directed to the source of the laser radiation.

The results of experimental studies of the spatial characteristics of multiple filamentation terawatt femtosecond Ti:Salaser in water are presented. With an increase in initial power laser pulses increases the number of filaments, the length of the field is increased filamentation and reducing the length of the filaments have been shown. The distribution of the filaments in the longitudinal direction of the field of multiple filamentation has a maximum cross-sectional filament is shifted from the center to the periphery of the beam at the end region of filamentation. The minimum diameter of the beam on the track corresponds to the position of the maximum number of filaments. After the point of maximum impulse essentially loses energy in the initial direction of propagation. Upon reaching the pulse power 2 10⁴ P_cr of multiple filamentation area is formed of a hollow cone, the apex directed to the radiation source.

The influence of the optical inhomogeneities effect of the prism stretcher elements on the spatial, angular and spectral parameters of the transmitted radiation and the degree of change in the phase aberrations of the laser beam during its propagation in the stretcher are studied. It is shown that the prism material does not allow transmitting of a required diameter of 75 mm without linear distortions of the beam. The maximum intensity and beam diameter allowing to amplify the picosecond pulses in XeF(C-A) amplifier are determined.

The results of laboratory experiments and numerical calculation of propagation of high-power terawatt femtosecond laser radiation via different media (air, glass and water) are represented. The experiments have been made on femtosecond Ti:Sa-laser system of IAO SB RAS. The spatial features of high-power terawatt femtosecond laser radiation are presented also. The ability of control of the position of the beginning of the field filamentation and angle of divergence of supercontinuum on high-power terawatt femtosecond laser radiation via plane parallel plate (glass) are found. The values of the location of the high value of the backscattering depending on filamentation conditions and the characteristics of supercontinuum and lidar system are obtained. The ability of the remote sensing of cirrus clouds with the help of high-power terawatt femtosecond laser radiation is discussed. The results of interactions of high-power terawatt femtosecond laser radiation and ice hexagonal plate crystal depending upon location of this crystal and filamentation conditions are represented.

The experimental results of the inversion population mechanisms study in the resonant electronic transition B³Π_g–A³Σ_u⁺ of nitrogen ions by optically pumped of air and pure nitrogen by femtosecond laser pulse at a wavelength of 950 nm are presented. It is shown that the inversion results from selective settling of N₂⁺(B²Σ_u⁺, v' =0) excited state by multiphoton excitation of the autoionization states of the nitrogen molecule with energy of 18.7 eV. Seed photon for superradiance at transitions of molecular nitrogen ions are photons the axial supercontinuum occurring in the filament on the respective wavelengths. The mode of the superradiance at a wavelength λ = 358.4 nm referred to the transition of the CN molecules was realized.

Recent theoretical and experimental studies show that filamentation of femtosecond pulses in middle infrared range in solids can generate intense supercontinuum (SC) with width of a several octaves. The structure and dynamics of the spectrum formation is different from those observed during filamentation of femtosecond pulses in the near infrared range of the spectrum. With numerical modeling we investigate features of infrared (IR) SC generation in a number of solid-state media transparent in a broad infrared range with various bandgaps, including KBr (7.6 eV), ZnS (3.68 eV) and ZnSe (2.71 eV) for different pump wavelengths. SC formation dynamics is analyzed. With comparison of different media, including one with artificial bandgap, we find that lower bandgap decreases SC bandwidth and filamentation length.

We present the results of studies of energy accumulation during the non-destructive interaction of extremely intense near infrared laser radiation with model wide band gap dielectric crystals of lithium fluoride, when the intensity of pulses is sufficient for effective highly nonlinear absorption of light and for the excitation of the electron subsystem of matter and the energy of pulses is still not sufficient for significant heating, evaporation, laser breakdown or other destruction to occur. We studied the emission of energy in the form of light sum of thermally stimulated luminescence accumulated under conditions of self-focusing and multiple filamentation of femtosecond laser radiation. It was established that it's the F₂ and F₃⁺ color centers and supplementary to them centers of interstitial type which accumulate energy under the action of a single femtosecond laser pulses. When irradiated by series of pulses the F₃, F₃^- and F₄ centers additionally appear. F₂ centers are the main centers of emission in the process of thermally stimulated luminescence of accumulated energy. The interstitial fluoride ions (I-centers) are the kinetic particles. They split off from the X₃^- centers in the result of thermal decomposition of latter on the I-centers and molecules X₂⁰. I-centers recombine with F₃⁺ centers and form F₂ centers in excited state. The latter produce the characteristic emission spectrum emitted in the form of thermally stimulated luminescence.

Evolution of spatial and energy characteristics start pulse with energy of 0.8 mJ in duration of 2 ps in the XeF(С-A) amplifier of THL-100 laser system have been studied experimentally and by numerical simulation. Laser radiation energy E = 2 J was obtained experimentally. In that work we present the 3D-model amplification of conically diverging laser beams, that takes into account the spatial inhomogeneity of the pump, and the geometry of THL-100 laser system amplifier. Description and the test results of the model are submitted. At the start pulse energy 0.8 mJ, the calculated radiation energy at the XeF(С-A) output reaches 2.4 J. Simulation results shows that, maximal intensity of the laser radiation in this mode reaches P = 60 GW/cm². The evolution of the energy and space-time structure of the laser beam in the amplifier was investigated. It is shown that in the ideal case (excluding the processes of nonlinear interaction of laser beam with an active medium), at the start pulse energy of 5 mJ, the energy of the laser radiation at the output of the amplifier is increased to E_out = 3.8 J. In this mode, the maximal radiation intensity reaches a value of I = 148 GW/cm².

The paper presents the results of theoretical and experimental studies of the second harmonic generation process in the Ti:sapphire femtosecond complex, which includes a generator of the femtosecond pulse, stretcher, regenerative amplifier, two multi-pass amplifiers, compressor and second-harmonic generator. This complex provides the 50-fs pulses with energy of 20 mJ and it is used as a master oscillator in THL-100 hybrid laser system, which operates in the visible region at a wavelength of 475 nm. Experiments and calculations for various beam parameters of the fundamental harmonic, such as radiation intensity, spatial profile of the beam and the level of the noise component were performed. It is theoretically shown that in the absence of the noise component in the beam of the fundamental wave a good uniformity of the second harmonic should be observed. When making the amplitude heterogeneities in the first harmonic even greater heterogeneities in the second harmonic are appeared. It is experimentally shown that with increasing of energy beam the inhomogeneity of the second harmonic beam increases.

The results of natural experiments of the propagation of powerful femtosecond laser radiation in glass and water, accompanied by multiple filamentation, and the results of numerical simulation of the process are presented. Based on the diffusive equations for density of the number of filament estimates of the positions of maxima in the number of filaments were obtained. Sufficient criterion of macroscopic refocusing for density of the number of filaments was established.

In our work we investigated different optical characteristics of five diamond samples that were supposed to be pure. The characteristics were the following: optical absorption spectra in the range 200 nm – 15μm, Raman scattering spectra in the range 100-3700 cm^-1 and photoluminescence spectra in the range 200 – 850 nm. The temperature of diamond samples was varied from 80 to 300 K. Photoluminescence was excited by KrCl*-laser radiation (λ=222 nm) with pulsewidth of 8 ns (FWHM) and peak intensity of 13 MW/cm². We found out that the band of radiative recombination of the electron-hole liquid (with the maximum at 240 nm) can be observed in the photoluminescence spectra if the absorption coefficient of the diamond sample is less than 10 cm^-1 in the range 225-226 nm.

In the present report we studied the distribution of surface potential of the HgCdTe epitaxial films grown by molecular beam epitaxy after the impact of picosecond electron beam and volume discharge in atmospheric-pressure air. The surface potential distribution was studied by the Kelvin Force Probe Microscopy. The experimental data obtained for the variation of the contact potential difference (ΔCPD) between the V-defect and the main matrix of the epitaxial film. The investigation of the origin epitaxial films show that variation of the spatial distribution of surface potential in the V-defect region can be related to the variation of the material composition. The experimental data obtained for the irradiated samples show that the mean value of ΔCPD for the original surface differs from the one for the irradiated surface for 55 eV. At the same time the mean value of ΔCPD changes its sign indicating that the original surface of the epitaxial HgCdTe film predominantly contains the grains with increased cadmium content while after the irradiation the grains possess an increased content of mercury. Therefore, during the irradiation process a decrease of the mercury content in the near-surface region of the semiconductor takes place resulting in the alteration of the electrophysical properties in the films near-surface region.

Laser ablation of bulk targets in a fluid — a promising new method for the synthesis of "pure" nanocolloids. Nanocrystalline materials produced by laser ablation are widely used in biology, medicine, and catalysis. High local temperature during ablation and large surface area of the particles promote chemical reactions and the formation of a complex composition of nanoparticles. In this paper the characteristics of the process of ablation and the obtaining of nanoparticles in a liquid by laser ablation of active materials (Zn, Ce, Ti, Si) were studied. Ways of increasing the productivity of laser ablation were discussed. Characterization of nanocolloids and nanocrystalline powders were performed.

The purpose of this paper was investigating the effect of volume nanosecond discharge in air at atmospheric pressure on the electro-physical properties of the HgCdTe (MCT) epitaxial films grown by molecular beam epitaxy. Hall measurements of electro-physical parameters of MCT samples after irradiation have shown that there is a layer of epitaxial films exhibiting n-type conductivity that is formed in the near-surface area. After more than 600 pulses of influence parameters and thickness of the resulting n-layer is such that the measured field dependence of Hall coefficient corresponds to the material of n-type conductivity. Also it is shown that the impact of the discharge leads to significant changes in electro-physical characteristics of MIS structures. This fact is demonstrated by increase in density of positive fixed charge, change in the hysteresis type of the capacitance-voltage characteristic, an increase in density of surface states. The preliminary results show that it is possible to use such actions in the development of technologies of the controlled change in the properties of MCT.

The paper presents the results of an examination of aluminum samples exposed to runaway electron preionized diffuse discharges in air, nitrogen, and argon at atmospheric pressure. The changes in the chemical composition, structure, and hardness of the aluminum surface layers caused by the action of the discharge were investigated. It has been found that the oxygen and carbon concentrations in the surface layers depend on the number of discharge pulses and on the chemical composition of the working gas. The goal of the study was to find possible uses of runaway electron preionized diffuse discharges in research and industry.

Characteristics of a laser on polycrystalline ZnS:Fe²⁺ subjected from two sides to diffuse doping at room temperature are investigated. The sample was pumped by a non-chain electrodischarge HF laser with the radiation pulse FWHM duration of ~140 ns. The diameter of pumping radiation spot on the surface of crystal was 3.8 mm. Further increase of the size of pumping spot was limited by parasitic generation arising due to a high concentration of Fe ions in the near-surface layer of sample at a relatively small depth of doping (short length of active medium). The output energy of ZnS:Fe²⁺ laser was 25.5 mJ at the slope efficiency with respect to the energy absorbed in the crystal of 20%. Characteristics of lasers on polycrystalline ZnS:Fe²⁺ and ZnSe:Fe²⁺ have been compared in equal pumping conditions. The slope efficiency of ZnSe:Fe²⁺ laser was 34%. At equal pumping energy absorbed in the samples, the duration of ZnSe:Fe²⁺ laser radiation pulse was longer than that of ZnS:Fe²⁺ laser. Possibilities of increasing the efficiency of ZnS:Fe²⁺ laser operation at room temperature by improving the technology of sample manufacturing and reducing the duration of pumping pulse are discussed.

The results of the modification of stainless steel, niobium and titanium by volume discharge induced by a beam of runaway electrons in air under normal pressure are presented. Changes in the chemical composition of the surface layers of metal by the action of the discharge, structural changes and changes of hardness were studied. It has been found that the concentration of oxygen and carbon in the surface layers of the samples depend on the number of discharge pulses. The aim of this work is to find possible application of this type of discharge in science and industrial production.

The paper presents the results of examination of copper samples exposed to a diffuse discharge initiated by a runaway electron beam in air under normal pressure. The changes in the chemical composition of the surface layers of copper caused by the action of the discharge were investigated. It has been found that the oxygen and carbon concentrations in the surface layers depend on the number of discharge pulses. The study was aimed at finding possible ways of using this type of discharge in research and industry.

The inactivation of eggs of Opisthorchis felineus and Diphyllobothrium latum in the water under the action of UV excilamps at 222 and 282 nm in dependence on the surface dose of radiation was studied. It was observed that the water disinfection from eggs of helminthes was more efficient at 222 nm, than at 282 nm. At the surface dose up to 5 mJ/cm² of UV radiation at 222 nm up to 85 % of Opisthorchis felineus eggs were inactivated. At the comparable surface dose of UV radiation at 222 nm up to 56 % of Diphyllobothrium latum eggs were inactivated.

A short overview of Laser Induced Breakdown Spectroscopy (LIBS) with emphasis on the new trends is presented. Nowadays, due to unique features of this technique, LIBS has found applications in a great variety of fields. Achievements in the application of LIBS in nuclear area, for hazardous materials detection and in geology were considered. Also, some results recently obtained at VINCA Institute, with LIBS system based on transversely excited atmospheric (TEA) CO₂ laser, are presented. Future investigations of LIBS will be oriented toward further improvement of the analytical performance of this technique, as well as on finding new application fields.

Applicability of a KTA crystal-based laser system with optical parametric generation to lidar sounding of the atmosphere in the spectral range 3–4 μm is studied in this work. A technique developed for lidar sounding of trace atmospheric gases is based on differential absorption (DIAL) technique and differential optical absorption spectroscopy (DOAS). The DIAL-DOAS technique is tested to estimate its efficiency for lidar sounding of atmospheric trace gases.

Ab-initio study on modification of commerce terahertz spectrometer with time resolution Z-3 (Zomega, USA) by substitution of ZnTe and GaP detectors and LT-GaAs generator for homemade of pure and S-doped GaSe is carried out. It was established that in spite of not optimized parameters pure and doped GaSe:S(0.3 mass%) crystal are comparable, relatively, in generation efficiency and detection sensitivity to commerce units due to lower nonlinear optical loss and much higher damage threshold. The advantages are in force from pump fluences of below 5 mJ/cm² for pure GaSe. The closer S-doping to optimal concentration, the lover fluences resulting in the advantages. Pure and S-doped GaSe demonstrate higher reliability and larger dynamic range of operation. Recorded absorption spectra well match known spectra.

Doping of polymer particles by a fluorophores results in the sensitization within the visible spectral region becoming very promising materials for sensor applications. Colloids of biocompatible chitosan-based polyelectrolyte complexes (PECs) doped with quantum dots (QD) of CdTe and CdSe/ZnS (with sizes of 2.0-2.4 nm) were synthesized and characterized by scanning electron microscopy, dynamic light scattering, ζ-potential measurements, absorption and luminescence (including time-resolved) spectroscopy. The influence of ionic strength (0.02-1.5 M) on absorption and photoluminescence properties of encapsulated into PEC and unencapsulated quantum dots was investigated. The stability of the emission intensity of the encapsulated quantum dots has been shown to be strongly dependent on concentration of quantum dots.

The paper studies the dynamics of a nanosecond diffuse discharge with no additional preionization at a voltage rise time of less than 1 ns and its effect on drinking and distilled water. It is shown that the diffuse discharge is formed due to avalanche charge multiplication initiated by fast electrons and is sustained by secondary breakdown waves through ionized gas channels. Fourier transform infrared spectroscopy reveals that repeated exposure to the discharge changes the absorption spectra of drinking and distilled water such that the stretching vibration band of OH groups broadens and lacks clearly defined peaks. The water conductivity after irradiation increases. Probably, this is due to cluster rearrangement of water molecules.

The paper revealed the using of industrial production equipment ALTI "Karavella-1", "Karavella-1M", "Karavella-2" and "Karavella-2M" precision components of IEP production [1–4]. The basis for the ALTI using in the IEP have become the positive results of research and development of technologies of foil (0.01–0.2 mm) and thin sheets (0.3–1 mm) materials micromachining by pulsed radiation CVL [5, 6]. To assess the micromachining quality and precision the measuring optical microscope (UHL VMM200), projection microscope (Mitutoyo PV5100) and Carl Zeiss microscope were used.

Research on CVL installations with an average power of 20–25 W of cutting and drilling has shown wide range of applications of these lasers for micromachining of metals and a wide range of non-metallic materials up to 1–2 mm. From the analysis indicated that peak power density in the focused light spot of 10–30 μm diameter must be 10⁹ –10¹² W/cm² the productivity and quality micromachining, when the treatment material is preferably in the evaporative mode micro explosions, followed by the expansion of the superheated vapor and the liquid. To achieve such levels of power density, a minimum heat affected zone (5– 10 μm) and a minimum surface roughness of the cut (1–2 μm), the quality of the output beam of radiation should be as high. Ideally, to ensure the quality of the radiation, the structure of CVL output beam must be single-beam, diffraction divergence and have at duration pulses τi = 20–40 ns. The pulse energy should have low values of 0.1–1 mJ at pulse repetition rates of 10–20 kHz. Axis of the radiation beam instability of the pattern to be three orders of magnitude smaller than the diffraction limit of the divergence. The spot of the focused radiation beam must have a circular shape with clear boundary, and a Gaussian intensity distribution.

Nanoparticles of layered GaSe, InSe were fabricated by laser ablation (LA) method (KrF laser, λ = 248 nm, 50 Hz, maximum energy 200 mJ, τ = 4 ns) and characterized by: •XRF; •GDOES; •SEM and TEM; •UV-, VIS-, and IRabsorption; •Raman and PL spectroscopy (also in confocal geometry). Results are discussed in relation to the particle size. Absorption spectra of particles with diameter 20 nm and less turned out to be blue shifted and is consisted with a weak confinement effect on Wannier-Mott type excitons. It is shown, that with decreasing the particle size the energy position of the low-frequency Raman active phonons in both compounds are shifted to lower frequencies (21 and 18 cm^-1 in bulk GaSe and InSe and 8 and 7 cm^-1 in particles with sizes 5 and 7 nm, respectively). From the low frequency Raman data, decrease of the force constants ca. 25 % (for GaSe) due to the formation of the nanoparticles are estimated, and the origin is suggested. Second harmonic generation (SHG) with 1064 nm line of a mode locked Nd : YAG laser was observed for nanoparticles ablated on different substrates. Potential for using these structures for laser light visualizators are discussed.

Remote sensing of contaminations on water and earth surfaces (oil spills, films) taking place during oil-gas extraction is an interesting and actual problem. This problem may be solved by using different methods of optical spectroscopy, including: •Raman scattering; •light induced breakdown spectroscopy (LIBS); •fluorescence spectroscopy. Fluorescence Light Detection and Ranging (LIDAR) LIDARs are successfully used for remote sensing of chemical and biological substances at atmosphere. A new laser induced fluorescence (LIF) KA-14 LIDAR system for detecting of oil spills on the sea surface was employed at the National Aviation Academy of Azerbaijan. LIDAR’s parameters are as follows: •laser CFR 200- type QUANTEL, λ = 355 nm, beam Ø = 5.35 mm, f = 20 Hz, pulse duration τ = 7 ns, pulse power 60 mJ; •diameter of Newtonian- type telescope is 200 mm; •collimator expansion of the laser beam diameter- not less than 3; •angle range of telescope measurements relative to horizon: from -20 to +20 degree; •spectral range of measurements: from 380 to 750 nm, number of spectral channels- 32; •maximum range of measurements- not less than 250 m. This LIDAR is the first performing these kind of research not only on the Azerbaijan beach of Caspian sea, but also on the earth places of Absheron peninsula, where oil-gas production takes place. We hope that the performance of LIDAR will have an International recognition and will make noticeable input on the International Research of Caspian sea surfaces.

The aim of study is to demonstrate that separation of solvated ions in solution of mix of salts under the action of external periodic electric field happens because of around ions there are formed clusters consisting of molecules of solvent and the sizes of such clusters have dimensions ~ 0.1 μm.

In investigations the sizes of clusters theoretically were defined and experimentally value of frequency of external electric field which action excites the effect of separation of the solvated ions was defined.

Experiments were done in the Technical Physics Chair of the National Research Tomsk Polytechnic University.

At theoretical determination of the dimensions of clusters Poisson's equation was solved and was considered that polar molecules of solvent are oriented under the action of electric field of an ion. The chemical composition of samples of solutions was determined by means of the spectrophotometry and he X-ray excited fluorescent radiation analysis method.

Theoretical estimates and results of experiments confirmed the assumption that clusters which are formed around ions in solutions have the dimensions ~ 0.1 μm.

Results of investigation testify that placing of volume distributed electric charge of ion in dielectric liquid is accompanied by formation of the supramolecular particles, which we called "clusters", linear sizes of which is significantly more than first and second radiuses of solvation (~ 1 Angstrom) and reach size ~ 0.1 μm. At such sizes inertial properties of clusters and their natural frequencies give the chance to operate their movement by means of action of external electric field on solution.

This work scales the present globalism of ecological and energetic problems. The ecological problem is connected with environment pollution by polymeric waste. The energetic problem - with traditional approaches of modern energetic, in particular, use of fossil fuel for energy production and concentration of capacities for ensuring overall performance of global power supply systems that doesn't guarantee a sustainable development of power for long prospect, doesn't provide power safety of the country. The second part of work is devoted to a choice of the most effective solutions of the present global problems. The authors have proposed the plasma-chemical method of the polymer waste processing and developed a schematic diagram of the reactor. The paper contains the results of the theoretical calculation of the polymer waste processing products. The reagents, allowing to obtain hydrogen and other liquid products from polymer waste are selected. It is proposed to use rare elements for increasing the efficiency of hydrogen production from polymer waste. The results of the calculation of the efficiency of hydrogen production from polymer waste using molybdenum are revealed in the paper.

In this paper, a new form of plasma discharge in a liquid under intensive ultrasonic treatment exceeding the cavitation threshold has been explored in view of initiation of various physical and chemical processes. Furthermore, in this plasma discharge, nanoparticles of oxides of various metals with controlled shape and size of particles and narrow particles size distribution have been synthesized. Further research proved that ultrasonic cavitation during synthesis significantly affects the physical and chemical characteristics of nanoparticles. These nanoparticles can be used for formation of nanostructured coatings on surfaces of various materials by an ultrasonic technique.

In this study, plasma discharge in a liquid at intensive ultrasonic field above the cavitation threshold has been proven to be of great interest for initiation of various physical and chemical processes. In such surcharge, nanoparticles of tungsten oxide with controlled size and shape and narrow particle size distribution have been synthesized. Further exploration of synthesized nanoparticles has demonstrated that the factor of ultrasonic cavitation during the synthesis substantially affects physical and chemical characteristics of nanoparticles. Similar procedure might be effective for compounds of tungsten and rare-earth elements.

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 leading to obtaining gaseous products with volume part of hydrogen higher than 90% (up to gas chromatography data). Preliminary evaluations of energetic efficiency, calculated from combustion energy of hydrogen and initial liquids and electrical energy consumption have demonstrated the efficiency about 60-70% depending on initial liquids composition. Theoretical calculations of voltage and current values for this process have been done, that is in good agreement with experimental data.

Measurements of the diffuse reflection coefficients of organic and inorganic materials and media in solid, granular and liquid forms were made in the UV field of 230–400 nm. A single channel spectrometer with an integrating sphere was used. Relation between diffuse reflection coefficients and the structure and composition of the samples is discussed. These data allow us to estimate the prospect of machine vision systems application for the UV range in such areas as biology, geology, remote control of materials and media.

The paper presents the history of active optical systems development from a laser projection microscope to a laser monitor. The examples of object visualization and diagnostics of high speed processes hidden by the intense background radiation are discussed. These are the processes of laser-surface interaction, self-propagating high-temperature synthesis (SHS), the corona discharge in the air, the nanoparticle production process using a high-power fiber laser, and etc. The results obtained by different research groups suggest that high-speed metal vapor brightness amplifiers and active optical systems based on them need further research, development and novel applications.

Integrated photoluminescence spectra of two diamond samples under laser radiation excitation at 193 and 222 nm, depending on the temperature in the range of 80-300 K and the peak intensity in the range of 7-13 MW/cm², were investigated. At temperatures below 200 K, and the peak intensity of more than 10 MW/cm² of laser radiation at 222 nm, the radiative recombination band of electron-hole liquid was observed in integrated photoluminescence spectra of CVD diamond sample.

In recent years the terahertz time-domain spectrometer (THz TDS) [1] has emerged as a key measurement device for spectroscopic investigations in the frequency range of 0.1-5 THz. To date, almost every type of material has been studied using THz TDS, including semiconductors, ceramics, polymers, metal films, liquid crystals, glasses, pharmaceuticals, DNA molecules, proteins, gases, composites, foams, oils, and many others. Measurements with a TDS are made in the time domain; conversion from the time domain data to a frequency spectrum is achieved by applying the Fourier Transform, calculated numerically using the Fast Fourier Transform (FFT) algorithm. As in many other types of spectrometer, THz TDS requires that the sample data be referenced to similarly acquired data with no sample present. Unlike frequency-domain spectrometers which detect light intensity and measure absorption spectra, a TDS records both amplitude and phase information, and therefore yields both the absorption coefficient and the refractive index of the sample material. The analysis of the data from THz TDS relies on the assumptions that: a) the frequency scale is accurate; b) the measurement of THz field amplitude is linear; and c) that the presence of the sample does not affect the performance characteristics of the instrument. The frequency scale of a THz TDS is derived from the displacement of the delay line; via FFT, positioning errors may give rise to frequency errors that are difficult to quantify. The measurement of the field amplitude in a THz TDS is required to be linear with a dynamic range of the order of 10 000. And attention must be given to the sample positioning and handling in order to avoid sample-related errors.

The paper proposes a new atmospheric pressure plasma jet (APPJ) source for operation in air and nitrogen. The conditions for the formation of stable plasma jets 4 cm long are determined. Energy and spectral measurement data are presented.

Power distribution between electrons and positive and negative ions and effect of the distribution on radiative efficiency of XeCl^* (308 nm) and Xe₂^* (172 nm) excimer molecules in the dielectric barrier discharge in Xe-Cl₂ at various pressures and supply voltages have been studied and discussed. The discharge characteristics were simulated using the 1D fluid model. It was shown that at small chlorine fraction in the mixture ~0.1–1% the most emission of the DBD is observed in the B→X band of XeCl^* molecules at 308 nm: in most cases about 90%–95% of the discharge emission falls on the XeCl* radiation. Highest emission in the B→X band of XeCl^* is observed when electrons adsorb about 50 or a bit higher percent of the discharge power. In this case an optimum between emission power and radiative efficiency of XeCl^* UV emission is achieved. When the power absorbed by electrons reaches 70%, the radiation efficiency of Xe₂^* (at 172 nm) sharply increases and riches 10–11% at small increase or even decrease in radiation efficiency of XeCl^* (at 308 nm).

The paper provides a review of research data on applications of XeCl excilamps in agriculture and animal breeding. The data demonstrate a favorable effect of radiation produced by the excilamps on the fertility of animals (outbred mice and pigs) and on the growth of plants (flaxes, potatoes, carrots, cucumbers, conifers). Excilamp models adapted specially for use in stock-raising and grain storage complexes are now available. The research data obtained in 2012–2015 suggest that XeCl excilamps hold promise for prevention of diseases in indoor-housed pigs and for pre-sowing seed preparation.

A study was conducted emission spectra germicidal low pressure mercury lamp at currents 100–306 mA located in a closed opaque cavity. It is shown that the lamps located in the cavity with perfectly reflecting and absorbing internal surfaces, in the emission resonance line of mercury is dominant at λ_r = 253.65 nm. The same pattern is observed in the tube placed in a cavity with diffusely reflecting surface at a low current of about 100 mA. However the picture of spectrum changes at higher discharge current. The spectrum of the lamp with arc discharge at a current of 306 mA contains the maxima of the spectral lines. Its intensities are approximately described by Planck's radiation law at the temperature of 9270 ± 230 K. The mechanisms of establish thermal equilibrium are discussed.

Main parameters of plasma formed during the pulse and pulse-periodic runaway electron preionized diffuse discharge (REP DD) in argon, nitrogen and air at high pressure were measured. An electron concentration in the plasma of pulse and pulse-periodic REP DD in the elevated pressure argon was determined. Average for pulse value of electron density in the argon plasma of pulse REP DD was ~ 3·10¹⁵ cm^-3. Dynamics of electron density in the atmospheric-pressure plasma of the argon during the REP DD was determined. Measured average values of an electron concentration in the plasma of the pulse-periodic REP DD in atmospheric-pressure air and nitrogen were ~ 3·10¹⁴ and ~ 4·10¹⁴ cm^-3, respectively. In addition, for the plasma formed during the pulse-periodic REP DD in atmospheric-pressure nitrogen and air average values of an electron temperature and reduced electric field, as well their dynamics were determined. Average value of an electron temperature during the pulse duration for nitrogen and air plasmas was ~ 2 eV. Dynamics of an electron temperature and reduced electric field strength was registered. Data on rotational and gas temperatures in the discharge plasma of atmospheric-pressure nitrogen formed in pulse (T_r ≈ 350 K, T_g ≈ 380 K) and pulse-periodic (T_r ≈ 750 K, T_g ≈ 820 K) modes were obtained. In addition, measured value of vibrational temperature in REP DD’s plasma formed in pulse mode in nitrogen at pressure of 1 bar was T_v ≈ 3000 K.

In the work the influence of the processes characteristic for atmospheric pressure heavy inert gases discharge plasma on the value of the first Townsend ionization coefficient were investigated. Krypton plasma was considered. Calculations have shown that the greatest impact on the value of the first Townsend ionization coefficient has dissociative recombination of molecular ions, followed by descending influence processes occur: stepwise ionization, the electron-electron collisions and superelastic ones. The effect of these processes begins to appear at concentrations of electrons and excited particles higher than 10¹² cm^-3. At times shorter than the time of molecular ions formation, when dissociative recombination is absent, should expect a significant increase of the ionization coefficient.

Double peak phase matching was recorded during experimental study of parametric frequency converters based on GaSe, its solid solutions crystals like GaSe_1-xSx and ZnGeP₂. Its physical origins are identified as presence of twin, large difference between cut and PM angles, self-heating effect at appropriate conditions, mismatched second (Φ) phase matching angle and microdefects.

Design of top S-doped GaSe growth technology is completed. New methods for characterization of high optical quality crystals are proposed that allowed selection optimally doped crystals. Frequency conversion of fs pulses into 6.5–35 μm and into 0.2–4.5 THz is realized. S-doped crystals demonstrated advantages from 50–70% in the first experiments up to 8.5–15 times in the following experiments depending on experimental conditions.

A new effect of formation of non-stationary optical transmission spectrum of dispersion type in the propagation of nanosecond broadband laser irradiation through the inhomogeneous cylindrical layer of plasma in neon near the spectral absorption line with the wavelength of 650.6 nm has been observed and studied. It is demonstrated that in the process of interaction of laser irradiation with plasma near the long-wave area off the center of the spectral absorption lines, the amplification of light is observed, although there is no population inversion in the plasma. The conditions of formation of optical transmission spectra of dispersion type are determined. Possible mechanisms of the effect observed are discussed

Generation characteristics of laser on polycrystalline ZnSe:Fe²⁺ samples doped by the diffusion method have been investigated at room temperature under the pumping by an electrodischarge HF laser. With the sample doped from two sides (working surfaces) the obtained generation energy was E=253 mJ with the slope efficiency η_sl=33% and efficiency with respect to the absorbed energy η_abs≈28% at the elliptical shape of the pumping spot of dimension a×b=6.8×7.5 mm. It was established that possibilities of further increase of generation energy on samples of this type by increasing the pumping spot area (at a constant density of the pumping energy) are limited by developing parasitic generation that is inherent in lasers with disk geometry. First investigation results are presented for a laser on the polycrystalline sample produced by the technology capable of providing zero doping component concentration on the surface and a maximal concentration at the centre of the sample (sample with "internal doping"). Prospects are discussed for increasing the generation energy of ZnSe:Fe²⁺ laser at room temperature by developing multilayer samples on the bases of the doping technique mentioned.

A numerical simulation of the generation of supercontinuum (SC) in highly-nonlinear photonic crystal fibre pumped with picoseconds-long pulses has been done using the RK4IP algorithm. Simulation and experimental results are in good agreement. The supercontinuum will be used for further amplification.

Model study of not phase matched and phase matched optical rectification or down-conversion of Ti:Sapphire laser pulses at 950 nm into THz and far-IRrange in pure and S-doped GaSe single crystals is carried out. First, the ordinary and extraordinary wave dispersions of the GaSe refractive indices were measured by terahertz time-domain spectroscopy (THz-TDS). Measured data were approximated in the form of Sellmeier dispersion equations for 0.62 – 2000 μm range with using available shorter wave data.

The energy dissipation processes in dielectric barrier discharge KrCl- and XeCl-excilamps at various voltage, frequencies and pulse duration are revealed by a pressure jump method. It is offered and tested a way of radiation power calculation in conditions of non-uniform filling of device bulb by discharge plasma. The previous data (Pikulev A.A., Sosnin E.A., 2010-2013) are confirmed. The regularity was formulated: conditions of maximal ultraviolet radiation power corresponds to conditions of maximal heat release in plasma.

The influence of thermal deformation processes on the phase-matching temperature bandwidth of nonlinear frequency conversion in different uniaxial and biaxial crystals is determined by using the results of calculations and experimental measurements. It is shown that the temperature bandwidths in borate crystals differ considerably in the case of different methods of nonlinear crystal fixation.

Irradiation of various types of microfungi spores by vacuum ultraviolet radiation (VUV) (λ = 172 nm, 2 mW/cm² ) was carried out in this work. It was found, that the VUV radiation leads to inactivation of spores in the dose range 10-240 mJ/cm² , depending on the fungal species. Shadowing effect of overlapping layers of spores was observed. Protective property of melanin at λ = 172 nm has been proven experimentally. Presence of melanin in the cell structure led to an increase of the inactivation dose of VUV radiation in more than one order. Fluorescence microscopy have revealed differences in the structure of the membrane of control and irradiated spore. VUV irradiation of DNA samples (200 ng) at λ=172 nm showed almost complete absence of double-stranded DNA parts at doses of more than 240 mJ/cm² .

Absorption spectra of human breath in 10 μm region were recorded by the use of intracavity laser photo-acoustic gas analyzer based on tunable waveguide CO₂ laser. Healthy persons and patients with various diseases were studied. For determination of CO₂ concentration in exhalation samples gas analyzer was calibrated by reference gaseous mixture CO₂-N₂. It was obtained that CO₂ concentration values in human breath of healthy persons are greater than that of patients with various diseases.

The results of numerical simulation of application principal component analysis to absorption spectra of breath air of patients with pulmonary diseases are presented. Various methods of experimental data preprocessing are analyzed.

We consider the problem of finding concentrations of molecular gases in the models of exhaled air samples in terms of their absorption spectra. We introduce model spectra describing the exhaled air samples as linear combinations of the absorption spectra of individual molecular gases with given coefficients. The absorption spectra are calculated on the basis of the database HITRAN. The concentrations are determined using Principal Component Analysis and Canonical Correlation Analysis.

We explore the problem of thermal interaction of nanoparticles heated by laser radiation with a biological tissue after particle flow entering the cell. The solution of the model equations is obtained numerically under the following assumptions: a single particle is located in a neighborhood exceeding the particle size; the environment surrounding the particle is water with the conventional thermal characteristics. The model equations are deduced from the particle and the environment energy conditions taking into account the heat transfer in the particle and in its environment by conduction. We also assume that at the boundary between the particle and the surrounding water the perfect thermal contact takes place.

The numerical solution of the problem is carried out with the use of an implicit difference scheme and the sweep method. Two cases of the laser pulse action on a particle are considered: a single pulse and a series of pulses. The dynamics of the temperature isoline propagation is obtained at which protein denaturation occurs in the space around the metal nanoparticle in the cases when the particles are heated by a single pulse and a series of pulses. The dependence of the heating rate and the heating depth of the medium on the laser pulse repetition frequency is found.

The informative complex of the features in the task of diagnosis on a base of exhaled air absorption spectra analysis based on the training sequences using nonparametric algorithm of pattern recognition "k-nearest neighbors" and ordered enumeration algorithms characteristics and validation had been revealed.