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Magneto-Optical Effects in Colloidal Solutions of Barium Hexaferrite
摘要： Hydrothermal synthesis was used to obtain lamellar magnetic particles of barium hexaferrite, and colloidal solutions were prepared on their basis. Magneto-optical effects in colloid solutions of barium hexaferrite were examined. It was found that the aqueous colloidal solution of coarse planar particles of barium hexaferrite is a magneto-optical medium that is nearly two orders of magnitude more effective than the colloid formed from isometric cobalt ferrite particles. It was shown that measuring the frequency dependence of the magneto-optical effects and approximating the experimental data with the Debye function makes it possible to find the frequency f0 characteristic of the given colloid and to calculate the characteristic size of particles (or aggregates) creating the optical anisotropy in the colloid under the action of a magnetic field. A dichroism is observed in the aqueous colloid formed by coarse planar barium hexaferrite particles. This phenomenon is due to the change in the light scattering on coarse particles upon their orientation by a magnetic field.
关键词： lamellar magnetic particles,barium hexaferrite,colloidal solution,hydrothermal synthesis,magneto-optical effects
更新于2025-09-23 15:22:29
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Fluorescence Imaging for Ultrafiltration of Individual Nanoparticles from a Colloidal Solution in Track Membranes
摘要： We have used ? uorescence nanoscopy for direct imaging of adsorption of individual colloidal quantum dots of diameter ~10 nm (spherical core/shell CdSeS/ZnS semiconductor nanocrystals, functionalized by organic oleic acid ligands) in nanopores of a nuclear ? lter (a polypropylene track membrane with pores of diameter ~500 nm). We have shown that when a colloidal toluene solution passes through the pores of the membrane, the nanoparticles are completely retained at a depth of 10 μm.
关键词： nanopore,single-photon source,CdSe,membrane,nanoscopy,entangled-photon source,quantum dot,colloidal solution,microscopy,nanoparticles,ultra? ltration,oleic acid,nuclear ? lter,luminescence,polymer
更新于2025-09-23 15:21:21
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Tailoring the Core–Satellite Nanoassembly Architectures by Tuning Internanoparticle Electrostatic Interactions
摘要： The use of plasmonic nanoplatforms has received increasing interest in a wide variety of fields ranging from theranostics to environmental sensing to plant biology. In particular, the development of plasmonic nanoparticles into ordered nanoclusters has been of special interest due to the new chemical functionalities and optical responses that they can introduce. However, achieving predetermined nanocluster architectures from bottom-up approaches in the colloidal solution state still remains a great challenge. Herein, we report a one-pot assembly approach that provides flexibility in precise control of core?satellite nanocluster architectures in the colloidal solution state. We found that the pH of the assembly medium plays a vital role in the hierarchy of the nanoclusters. The architecture along with the size of the satellite gold nanoparticles determines the optical responses of nanoclusters. Using electron microscopy and optical spectroscopy, we introduce a set of design rules for the synthesis of distinct architectures of silica-core gold satellites nanoclusters in the colloidal solution state. Our findings provide insight into advancing the colloidal solution state nanoclusters formation with predictable architectures and optical properties.
关键词： optical responses,colloidal solution state,plasmonic nanoplatforms,core?satellite nanocluster architectures,pH-dependent assembly
更新于2025-09-23 15:21:01
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Laser ablation of Ni in the presence of external magnetic field: Selection of microsized particles
摘要： The study presents results of nanosecond laser ablation of a Ni target in a liquid as a method of producing contamination-free micro- and nanosized colloidal structures. The ablation was performed in two liquids – double distilled water and ethanol, as their role on the characteristics of the ablated material is clarified. The laser ablation method in liquid was extended by applying an external magnetic field during the ablation process. A separation of micron and submicron particles from the nanoparticles in the colloidal solution is achieved by placing a substrate in the liquid, where the micron size structures are deposited under the action of the external magnetic field. At certain experimental conditions, the deposition of ordered one-dimensional microstructures on the substrate can be realized. The influence of different laser wavelengths on the features of the nanostructures dispersed in the liquid and microstructures deposited on the substrate was also investigated. On the basis of detailed analyses using Optical Microscopy, Scanning Electron Microscopy, Selected area electron diffraction, and Transmission Electron Microscopy the morphology, composition, and size distribution of the fabricated structures were studied. The presented method allows the fabrication of contamination-free micro- and nanostructures with potential applications in biotechnology, catalysis, and magneto-optics devices.
关键词： Laser ablation in liquid,Metal nanoparticles,Microstructures,Colloidal solution,External magnetic field
更新于2025-09-23 15:19:57
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Applications of Laser Ablation - Thin Film Deposition, Nanomaterial Synthesis and Surface Modification || Application of Liquid Laser Ablation: Organic Nanoparticle Formation and Hydrogen Gas Generation
摘要： Laser ablation is induced by a heating process of materials through the absorption of laser light and results in an explosive expansion of materials. For materials located in liquid, in contrast to those in vacuum, laser ablation proceeds under rather mild conditions via a cycle of heating and cooling by mediated solvent; therefore, it is applicable for organic solids to fragment into nanoparticles. Alternatively, for effective light absorbers, the irradiated site becomes the reaction centre of a photochemical reaction even in liquids, resulting in hydrogen gas generation. In this chapter, two topics of laser ablation in the liquid phase are presented: nanoparticle formation of organic materials and hydrogen gas generation from solid carbon in water. Thereby, the extended abilities of liquid laser ablation to transform ordinary materials into functional ones are introduced.
关键词： spectroscopy,carbon-based nanoparticles,hydrogen generation,colloidal solution,nanosecond laser pulses,organic nanoparticles
更新于2025-09-12 10:27:22