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Petukh, M. L.; Rozantsev, V. A.; Shirokanov, A. D.; Yankovskii, A. A.

doi:10.1023/a:1004157412887

Journal of Applied Spectroscopy

2000

DOI: 10.1023/a:1004157412887

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M. L. Petukh

V. A. Rozantsev

A. D. Shirokanov

et al.

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Cited by 18 publications

(3 citation statements)

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“…Consequently, the size of the particles formed decreases, and also growth of particles is inhibited by their coalescence during collisions [12]. We should point out that laser pulses have been successfully used already for more than 30 years for the purpose of obtaining various metal compounds and spectral analysis [13][14][15][16][17][18].…”

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confidence: 99%

Synthesis of oxides and determination of uranium concentration in uranyl nitrate compounds using irradiation by double laser pulses

et al. 2011

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Spectroscopic studies of the surface of a porous solid containing micro amounts of uranyl nitrate hexahydrate using irradiation by two sequential pulses with pulse-to-pulse intervals in the range 4-12 μs have shown that laser chemical synthesis of uranium and uranium oxide nanoclusters within the interior of a porous solid is a promising technique, with the possibility at the same time of determining the uranium content with good sensitivity (~10 -10 g). Introduction. Research in the field of nanoclusters and nanosystems provides a basis for designing new 21stCentury technology: nanotechnology. Thus, for example, cluster catalysts make it possible to develop new directions in control of conversions and selectivity of catalytic reactions as a result of the cluster size and its interaction with the matrix [1]. Uranium oxides are quite attractive for catalysis due to the possibility of varying their stoichiometry over a broad range and varying the valence state of uranium depending on external conditions (temperature, amount of oxygen). In [2,3], it is shown that catalysts based on uranium oxides are active in reactions of exhaustive oxidation of hydrocarbons at low temperatures, and are resistant to the action of such catalytic poisons as sulfur, water, and halogens. We know that uranium oxide catalysts can also be used in partial oxidation processes [4,5]. Mixed Ni-U oxide systems are efficient in processes of conversion of methane to synthesis gas [1,6]. Uranium catalysts in the original state can contain compounds of the 3-, 4-, 5-, or 6-valent metal. This provides more diversity in the composition of active sites than when using derivatives of lanthanides, which generally have a trivalent state [7].

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confidence: 99%

Synthesis of oxides and determination of uranium concentration in uranyl nitrate compounds using irradiation by double laser pulses

et al. 2011

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“…It is important to identify the distinctive features of plasma formation in liquids with one and two pulse operation. We may assume that two pulse operation increases the ablation efficiency [11], mainly because of an enhanced intensity of the emission from atoms and ions in the laser ablation plasma and the greater sensitivity of laser spectral analysis when two pulses, rather than one, are used [12,13]. Furthermore, with two pulse operation it is possible to make smaller particles in the ablation flare owing to heating and fragmentation of particles formed by the first laser pulse.…”

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confidence: 99%

Laser-induced plasmas in liquids for nanoparticle synthesis

2010

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Spatially and temporally resolved emission spectroscopy is used to study the major features of the onset and evolution of plasmas created by pulsed laser irradiation of targets immersed in liquids. It is shown that double pulse operation provides an enhanced rate of nanoparticle formation and increases the emission signal from the plasma atoms and ions owing to more efficient ablation of the target material. The main parameters (density of atoms, electron temperature and density) of laser-induced plasmas in liquids are estimated. The prospects of laser ablation in liquids as a method for producing nanoparticles are analyzed.Keywords: laser-induced plasmas in liquids, double pulse ablation, electron density and temperature, spatially and temporally resolved emission spectroscopy.Introduction. In recent years there has been increased interest in the production and study of nanostructured materials. The structural elements of these materials have characteristic sizes in the range of 1-100 nm so they can have unique electronic, magnetic, and chemical properties which differ from those of the corresponding bulk materials. For example, nanostructured materials can have enhanced mechanical characteristics (hardness, durability), catalytic activity, or luminescence properties, which are absent or less marked in their macroscopic analogs. Thus, nanostructures offer great promise for heterogeneous catalysis and micro-and optoelectronics, and can be used as gas sensors in medicine, biology, and other areas [1][2][3].It should be noted that different methods of nanoparticle synthesis are used, depending on their size, shape, and chemical composition : physical methods based on vapor condensation [4], chemical methods using reduction reactions of metallic ions from solutions of their salts [5], and combined methods [6]. In a number of cases, nanoparticles are obtained in the form of colloidal solutions, which are most often produced by various chemical methods. The main deficiency of these methods is that, besides the nanoparticles, these solutions contain ions and other reaction byproducts which are often difficult to avoid. An alternative method of obtaining nanoparticles that is free of these deficiencies is laser ablation of solids in liquids [7-10].One of the advantages of the laser ablation technique is its universality -the possibility of using it for metals and alloys, semiconductors and dielectrics with different compositions, fairly extensive control of the properties of the synthesized particles by changing the parameters of the laser radiation, and the production of composite particles by ablation of multicomponent targets.Laser ablation of solids can take place in a gaseous atmosphere or in a liquid. In the latter case there is no need use costly vacuum systems and the problem of collecting the nanoparticles is comparatively simple, compared to the difficulties of doing so in gaseous atmospheres. With ablation in a liquid the nanoparticles remain in the volume of the liquid and form a colloidal solution.Although ...

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“…Here, the quantity of the substance vaporized from the sample by the second pulse and the radiation intensity of the cloud are increased. The time of the glow of plasma and correspondingly of the spectral lines is increased and the intensity of the background is decreased [4]. We applied defocusing of the laser beam; the size of the light spot was +900 µm.…”

mentioning

confidence: 99%

Layer-by-Layer Laser Spectrum Microanalysis of Easel-Painting Materials

Klyachkovskaya

Kozhukh²,

Rozantsev

et al. 2005

J Appl Spectrosc

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UDC 535.33A technique of layer-by-layer laser microanalysis of the materials of easel-painting works employing a twopulse scheme of substance excitation and registration of the spectrum from one double pulse is suggested. With paintings from the Nesvizh Portrait Gallery as examples, the effectiveness of the method in identification and attribution of paintings is shown.Keywords: pigments, layer-by-layer laser spectrum microanalysis, double pulse.Introduction. At the present time, in studying paintings, methods of art expertise are more often supplemented with methods of natural sciences. Comprehensive technical-technological investigation of a work of art that encompasses each structural element of the picture (base, primer, drawing, paint layer, protective coating) includes overall examination of the work by luminescent methods on exposure to UV and IR irradiation and by the x-ray graphical method as well as studying the paint materials used. The materials used in painting a picture are very diverse and are determined by the time of creation of a picture, the tradition of the artistic school, and also by the artistic individuality of a painter -his style and technique. Accumulation of information on the materials that were used at different times by various painters and the creation of a database are essential for the success of the investigations carried out.The most difficult problem in studying a work of art is determination of the pigments and binders that enter into the primer and paint layers. Pigments are identified by methods of microchemical analysis, petrography, and various physical methods, for example, x-ray structural analysis, as well as different kinds of spectral analysis (IR Fourier spectroscopy to identify the binder and an emission analysis to identify pigments). The x-ray structural analysis has some limitations because the intensity of a spectrum depends on substance absorption, which, in turn, influences the sensitivity of the method. Therefore, registration of even a relatively high content of pigment with low absorptivity is difficult when this pigment is mixed with a highly absorptive component [1]. The spectral electric-discharge emission method allows one to rather exactly determine the chemical composition of a sample but needs a great amount of it. Moreover, it is extremely difficult to perform a layer-by-layer analysis by this method.In the present work, we suggest a method of two-pulse laser spectrum microanalysis of the chemical composition of easel-painting materials. Its advantage over the electric-discharge method of spectral analysis lies in the fact that it needs no special preparation and it is local and provides the possibility of layer-by-layer examination of the chemical composition of the materials of the work studied.Experimental Technique. Model samples have a multilayer structure with known chemical composition of each layer. As the base for the two samples prepared by us, a linen canvas was used primed by titanium white on an oil binder. The paint layer of the first...

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Cited by 18 publications

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Synthesis of oxides and determination of uranium concentration in uranyl nitrate compounds using irradiation by double laser pulses

Synthesis of oxides and determination of uranium concentration in uranyl nitrate compounds using irradiation by double laser pulses

Laser-induced plasmas in liquids for nanoparticle synthesis

Layer-by-Layer Laser Spectrum Microanalysis of Easel-Painting Materials

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