This work is dedicated to study of the morphology of craters formed on the surface of HPHT synthetic diamond plates under the influence of high-power laser radiation during their studies by Laser-induced breakdown spectroscopy (LIBS). Samples of diamond plates were irradiated with both individual laser pulses and series of up to 30 pulses at one point. Analysis of the obtained results shows that the shape of the crater depends on several factors: the energy of the laser pulse, the number of pulses in the series, and the crystallographic orientation of the plate. The influence of the laser pulse energy value is manifested in the transition from an oval to a polygonal crater shape. The crystallographic orientation of the plate affects the shape of the polygonal crater: in the direction of the cube <100>, rectangular pyramidal depressions with a linear or point bottom are formed, and in the direction of the octahedron <111>, triangular flat-bottomed depressions are formed.

The paper presents the results of experimental observation of two types of stimulated emission (SE) under pulsed laser pumping at 532 nm in diamond with NV centers. A comprehensive spectroscopic characterization of multisectorial HPHT diamond plate was performed. At low pumping power, the stimulated emission from NV- centers was recorded as a broad (>= 80 nm wide) band with a maximum at 706 nm in the {111} and {311} sectors of the diamond plate. As the pump power increased in the {111} sector, narrow-band stimulated emission (<10 nm wide) was detected, with a maximum at 716 nm and a luminescence impulse duration of 1.5-3 ns. As the pump density increased, a fine structure in the spectrum of narrow-band stimulated emission was revealed for the first time. The concentration of NV- centers in the {111} and {311} growth sectors was approximate to 10 ppm. However, there were considerable differences in the concentrations of C (35 and 3.5 ppm) and C+ centers (6.1 and 3.2 ppm, respectively). It was demonstrated that the presence of a high concentration of NV- centers is not the only necessary condition for the initiation of narrow-band SE in the 710-720 nm range. In the {311} sector, lighting at 360, 405, and 488 nm reduced the concentration of NV- centers by 15 % while increasing the concentration of C+ centers in the {311} sector. This effect is weak in the {111} sector. The authors suggested a model for narrowband SE at the transition Valence Band -> C+ with charge-state conversion of C <-> C+ and NV0 <-> NV- centers. Further research on the dynamic processes is required in order to a detailed understanding of the operation of NV centers in diamond during SE generation.

Data on direct observation of stimulated emission of $\mathrm{NV}^{-}$centres in synthetic NRNT-diamonds located in a focused pump beam are presented. The spectra and pulse durations of the stimulated emission were simultaneously recorded. It was found that the shapes of the spectra and the intensity of stimulated emission depend on the number of emitting centres and the position of the crystal relative to the focus of the pump beam.

The article presents the results of micro- and macro morphology studies of HPHT diamond surface after laser-induced breakdown spectroscopy measurement of diamond plates. The article describes the characteristic features of the interaction of laser beams with the surface of sectorial HPHT diamond plates. It was discovered that the mechanism of graphitization during LIBS measurements depends on the crystallographic orientation of the plate, the presence and concentration of the doping element, and its distribution over the diamond growth sectors.

An analysis of the schemes for recording the spectra of wine during optical breakdown was made on the surface, in the bulk of a liquid, in vapors during its boiling, and in the form of a resinous sediment. It is shown that the intensity of the plasma emission spectrum decreases exponentially as the focus of the laser beam moves away from the liquid surface. It was found that the intensity of the plasma emission in wine vapors is lower than by ablation from the surface. In vapors, a less quantity of spectral lines was observed due to the nonstoichiometric nature of the evaporation process. In the spectra of wine detected C, Si, Ca, Mg, Fe, Ti, CA 125 monoclonal antibody and Mn, Sr, As were also found in the sediment spectra.

The structure and impurity composition of the surface of multi-sector HPHT- diamond plates doped with nitrogen or boron were analyzed by laser-induced breakdown spectroscopy. Changes in the plasma spectra in the process of laser-induced transformation of the test sample surface under the action of a series of laser pulses at one selected point were recorded. It was found that after such a laser action on the sample, a different degree of surface graphitization occurs, which depends on the degree of doping of diamond with nitrogen or boron and on the crystallographic orientation of the growth sectors. In this case, an increase in the sensitivity of the LIBS method is also observed. As a result of such a difference in the process of graphitization, it becomes possible to identify the boundaries of the sectoral structure of samples and atomic structures with different strengths of interatomic chemical bonds of carbon and hydrogen. A fast algorithm for spectra processing with their normalization after each laser pulse turned out to be effective in studying samples in real-time mode. Based on the results of the measurements, experimental dependences of impurity distributions in different sectors of multisector HPHT- diamond plates doped with nitrogen or boron were obtained. Moreover, the shape of dependences for various impurities obtained in the process of pulse-to-pulse laser-induced transformation of the HPHT- diamond surface can serve as a criterion for the degree of disorder in its structure

An analysis of the spectra of laser-induced plasma under multi-pulse exposure of a focused laser beam at each point under study on the surface of multi-sector diamond plates doped with nitrogen and boron was performed. A different degree of surface graphitization was found depending on the crystallographic orientation of the growth sectors, the type of doping element, and the degree of doping. The possibility of revealing the sectoral structure of samples and atomic structures, including impurity ones, with different strengths of interatomic chemical bonds is shown.

The paper considers the applied optical spectroscopy methods application in the defluorinated phosphate production, controlling the technological process task. The emission spectral analysis using the method possibilities to control the charge hydrothermal acid processing process, which takes place in special furnaces with natural gas burning and a temperature of 1340 – 1400°C, have been studied. Experiments have been carried out in production conditions, and the radiation spectral characteristics study results from the furnace during the defluorination technological process are presented. It is shown that, by measuring individual spectral lines, it is possible to provide an automatic control mode for the defluorination technological process in the furnace burner controlling the combustion mode terms without the need for visual observation by the operator to ensure a better product yield. The work second part is devoted to the defluorinated phosphate chemical composition study by the laser-spark emission spectrometry method (LIBS). The LIBS method application for the defluorinated phosphate chemical composition analysis is proposed, which allows the production process parameters real-time control. The plasma spectra measurement and interpretation results from the ready-made defluorinated phosphate sample, obtained using the LIBS method, are presented.

The impurity composition of multi-sector plates of nitrogen and boron-containing synthetic HPHT diamonds has been investigated by laser-induced breakdown spectroscopy. It is shown that a comparative analysis of the intensities of the characteristic atomic and molecular bands in the plasma emission spectrum during laser-induced modification of the surface of the samples makes it possible to distinguish both the type of diamond and the crystallographic orientation of the analyzed sector of the sample.

The article describes approaches to creating a laser system that generates radiation simultaneously at two wavelengths, both in the infrared and ultraviolet range. The laser system is based on a pulsed Nd: YAG laser with self-phase conjugation. The generation of synchronized pulses at wavelengths of 1064 and 355 nm is a distinctive feature of the laser system. Ultraviolet pulses are part of the converted fundamental radiation into the third harmonic. Also, energy impulses are equal. The problem is considered in the direction of remote measurements using laser-induced breakdown spectroscopy.

Analysis of impurities in multisectoral plates of boron- and nitrogen-doped synthetic HPHT diamonds was performed by laser-induced breakdown spectroscopy. It was shown that comparative analysis of plasma emission bands during laser-induced graphitization process is effective approach to distinguishing types of diamonds and crystallographic orientations of sectors.

Comparative analysis of atomic and molecular bands in plasma emission spectra of various multi-sectoral HPHT diamond plates was performed. It was shown that laser-induced breakdown spectroscopy is an effective approach to determination of crystallographic orientations of growth sectors of diamonds and impurities incorporation level.

The study of multi-sector plates of nitrogen- and boron-containing synthetic HPHT diamonds by laser- induced breakdown spectroscopy was carried out on a real-time basis. The obtained data were analyzed and compared with the data during scanning of the samples with the data of local measurements in the corresponding sectors of the crystals. Measurements and analysis of plasma emission spectrum in real time into account the process of laser-induced modification of the surface of the samples, makes it possible to distinguish both the type of diamond as well as the crystallographic orientation of the analyzed sector of the sample. It was found that in terms of the streaming measurement of plasma spectrum, a more careful selection of the modes of interaction of laser radiation with the surface of the samples is needed, which, in particular, affects the capabilities of the method in terms of spatial resolution.

A compact laser system based on a Nd: YAG laser with a wavefront self-reversal for remote analysis of substances by laser-induced breakdown spectroscopy at a distance of at least 10 m is proposed. The possibility of creating a reliable system for remote diagnostics of materials by laser-spark emission spectroscopy, including in real time, is shown.

Compact laser system based on Nd:YAG-laser with self-phase conjugation for remote analysis of substances at least ten meters distance by the Laser-Induced Breakdown Spectroscopy was proposed.

A compact laser system based on a Nd:YAG laser with self-phase conjugation for remote analysis of substances by laser-induced breakdown spectroscopy at a distance of not less than 10 m is proposed.

It was experimentally shown that, when nanosecond near-infrared laser pulses are applied to nanoporous silicate glass containing amorphous carbon, nanodiamonds are formed. The formation of these structures is confirmed by the spectra of luminescence and Raman scattering. Mechanisms explaining the observed effects are proposed. (C) 2019 Optical Society of America

For the first time CW laser oscillation on Er-Yb doped PTR glass with diode pumping is demonstrated. For the monolithic laser the maximum output power of 0.47W at wavelength of laser oscillation of 1574 nm and a slope efficiency of 6% was achieved.