Laser synthesis of a weakly agglomerated aluminium oxide nanopowder doped with terbium and ytterbium

This paper describes a method of femtosecond laser synthesis of nanoparticles of powdered aluminum oxide doped with terbium and ytterbium was developed. The formation of a plasma torch of nanoparticles of a powdery material is carried out as a result of ablation under the influence of a sharply focused beam of femtosecond laser radiation with an intensity of 108- 1010W/m2. The radiation source is the TETA-10 laser system. SEM images of the obtained nanopowders are presented. Spherical nanoparticles of narrow particle size distribution in the range from 5 to 15 nm was synthesized with the ability to control the size of nanoparticles by purposefully changing the parameters and characteristics of pulsed radiation in the treatment area. The design of a specialized high-voltage electrostatic precipitator up to 25 kV for capturing ablated nanoparticles in an electron cloud of increased concentration was developed.

Femtosecond laser synthesis and comparative analysis of fluorescent carbon dots from L-lysine aqueous solution

Laser synthesis of fluorescent species from biomolecules in living cells and tissues offers unique capabilities for fluorescent bioimaging, yet little is known about its mechanisms and characteristics of products. We examine synthesis of fluorescent products from water solution of L-lysine upon irradiation by trains of femtosecond laser pulses with varying parameters. We demonstrate that irradiation products contain nanoscale carbon-based fluorescent particles (carbon dots) with multi-colour and excitation-dependent emission. Morphology, chemical composition and fluorescent characteristics of irradiation products strongly depend on laser pulses parameters.

Plasmonic Si@Au core-satellite nanoparticles prepared by laser-assisted synthesis for photothermal therapy

We describe a laser-assisted methodology for the fabrication of Si@Au core-satellite nanostructures for photothermal therapy applications. The methodology consists in laser ablative synthesis of Si and Au NPs in water/ethanol solutions, followed by a chemical modification of the Si NPs by APTMS and their subsequent decoration by the Au NPs. We show that despite a relatively small size (< 40 nm) the formed core-satellites exhibit a strong plasmonic absorption peak centred around 610 nm and having a large tail over 700 nm overlapping with the first optical window of relative tissue transparency. Being relatively small and exempt of any toxic impurity due to ultraclean laser synthesis, the fabricated nanoparticles promise a major advancement of imaging and phototherapy modalities based on plasmonic properties of nanomatererials.

MODE INFLUENCE OF SELECTIVE LASER IMPACT UPON POROSITY OF SAMPLES OF COBALT, CHROMIUM AND MOLYBDENUM POWDERS

The purpose of this investigation consists in the analysis of possibility to obtain products by means of the SLP method using powders of cobalt, chromium and molybdenum having considerable difference in melting temperatures of cobalt (1768ºC), chromium (2130ºC) and molybdenum (2890ºC), density, thermal conduction and solving for the optimum technological modes of powder composition melting to obtain samples with lower porosity. The investigation methods include methods of physical material science. Investigation results and novelty: a procedure for obtaining a powder composite of the cobalt-chromium-molybdenum system for selective laser melting is developed. There are carried out experimental investigations on the selection of optimum technological modes for the layer-by-layer laser melting of a cobalt-chromium-molybdenum alloy of powder composition. A method for layer-by-layer laser synthesis for the solution of a principle matter – possibility for the synthesis of the products of cobalt chromium and molybdenum powders having a considerable difference in melting temperatures, density, heat conductivity and so on. The investigations of model alloy samples of cobalt-chromuim-molybdenum system obtained through the method of layer-by-layer laser synthesis on optimized technological modes through the methods of scanning electronic microscopy allow defining sample porosity. The generalization of obtained numerical and experimental investigation results and definition of essential conditions for selective laser melting allow optimizing modes and parameters of the synthesis. Conclusions: the optimum modes of selective laser melting for obtaining the samples with the powder composition of 66 mas. % Co, 28 mas. % Cr, 6 mas.% Mo through the method of selective laser melting with minimum porosity are: laser capacity P=100Wt, scanning rate v=350mm/s, modulation 5000Hz, scanning pitch s=0.1mm, layer thickness h=0.03mm, melting process takes place in protective argon environment.

Generation of an isolated attosecond pulse from aligned molecules via laser synthesis

A laser synthesis scheme via the superposition of single-color and hyper-Gaussian pulses is proposed, and the synthesized laser pulse is adopted to interact with pre-aligned molecules for the production of an isolated attosecond pulse (IAP). The numerical results based on strong-field approximation disclose that the proposed scheme is efficient for the generation of an IAP under suitable hyper-Gaussian parameters, and the intensity of an IAP is sensitive to molecular pre-alignment angles, and thus an optimal set of hyper-Gaussian parameters and pre-alignment angles can support the strongest IAP.

Laser Synthesized Graphene and Its Applications

Since graphene was discovered, a great deal of research effort has been devoted to finding more and more effective synthetic routes, stimulated by its astounding properties and manifold promising applications. Over the past decade, laser synthesis has been proposed as a viable synthesis method to reduce graphene oxide to graphene as well as to obtain graphene from other carbonaceous sources such as polymers or other natural materials. This review first proposes to discuss the various conditions under which graphene is obtained from the reduction of graphene oxide or is induced from other materials using laser sources. After that, a wide range of applications proposed for the obtained materials are discussed. Finally, conclusions are drawn and the author’s perspectives are given.