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Combined effects of nanosecond laser-induced surface oxidation and nanostructure formation for selective colorization of nickel surfaces
摘要： Metal surfaces can be nanostructured by laser irradiation making use of different effects ranging from thin film generation to nanostructures formation. Here, the colorization of pure nickel surfaces by nanosecond laser irradiation in air is demonstrated and studied in detail. Correlations between chromaticity coordinates and laser-processing parameter show that the accumulated fluence is the dominating factor in creation of a specific colored surface. The color of the laser-irradiated surfaces shows both angle-dependent and angle-independent in reliance on the processing conditions. The examination of the laser-colored surface demonstrates that lateral and vertical organized, laser-induced structures with nano-, micro-, and mesoscopic scales can be found simultaneously which contribute to the colorization in a particular manner. A comprehensive analysis of the processes involved in the color formation at nickel was performed by examining the surfaces by SEM, reflectometry, XPS, and XRD to verify the multi-process mechanisms of color formation. The most saturated colors result from interference effects within the redeposited layers. It was found that controlling the hatching distance applying optimized laser fluence enables a wider color range and allows a very precise setting of the color. Based on the extracted laser-processing parameters, the surface coloration of arbitrary pattern with desired optical properties becomes practicable, and nanosecond laser color marking can, therefore, be expanded to potentially new applications.
关键词： colorization,nanosecond laser,nickel surfaces,surface oxidation,nanostructure formation
更新于2025-09-11 14:15:04
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Interfacial Energy Transfer in Hollow Double-Shelled TiO <sub/>2</sub> : <i>x</i> %Eu <sup>3+</sup> @SiO <sub/>2</sub> : <i>y</i> %Tb <sup>3+</sup> Nanospheres for Tissue Imaging
摘要： In this paper, hollow double-shelled TiO2:x%Eu3+@SiO2:y%Tb3+ nanospheres (C1-Ti-x/Si-y) were fabricated using carbon spheres as hard template followed by a two-step sol-gel coating process. The results demonstrate that there is strong interaction between inner TiO2 layer and outer SiO2 layer, which can be characterized by the high surface content of Ti-O-Si bonds. The strong interaction makes it possible to achieve efficient energy transfer from Tb3+ to Eu3+ ions through crossing the double-shelled interface. The interfacial energy transfer (IET) efficiency from Tb3+ to Eu3+ions is strongly influenced by the doping concentration of Eu3+ ions whose maximum is determined to be 30.2%. Furthermore, the surface of inner TiO2 layer is modified by the outer SiO2 layer through this strong interaction, which significantly enhances the emission intensity and suppresses the concentration quenching of Eu3+ ions. Under 377 nm excitation, C1-Ti-x/Si-y simultaneously exhibits red and green emissions derived from Eu3+ and Tb3+ ions, respectively. Moreover, by varying doping concentration of Tb3+ and Eu3+ ions, the luminescence color of the samples can be tuned from green to orange and red. The characterization results show that our proposed phosphors may provide potential applications in tissue imaging.
关键词： Multicolor phosphors,Hollow double-shelled nanostructure,Interfacial energy transfer,Concentration quenching suppressed,Surface modification
更新于2025-09-11 14:15:04
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One-pot synthesis of nanostructured CdS, CuS, and SnS by pulsed laser ablation in liquid environment and their antimicrobial activity
摘要： We describe here a generic method for producing high-quality metal sulfide nanoparticles of a controllable and narrow size distribution in the nano-metric range. Metal sulfide nanostructures (CdS, CuS, and SnS) are synthesized by using nanosecond pulsed laser ablation in a liquid solution containing sulfur precursor in just one step (one-pot versatile synthesis method). The optical properties have been studied using UV–Visible spectroscopy showing the main characteristic transition peaks of metal sulfides. Transmission electron microscope (TEM) shows a uniform Smaller-sized and nearly spherical nanocrystals exhibited a cross lattice pattern. The structure study by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) reveal the purity and the spherical crystalline structure of all the prepared nano metal sulfides. After that, the antibacterial activity has been examined against four types of bacteria and unicellular fungi by using agar plate diffusion methods followed by studying the required time for killing. The tested microorganisms strain is showing that CuS nanoparticles have the highest antimicrobial activity.
关键词： Metal sulfides,PLAL,Antimicrobial,Laser ablation,Nanostructure
更新于2025-09-11 14:15:04
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Vapor-phase synthesis of bimetallic plasmonic nanoparticles
摘要： Regulating the nanostructure of composite nanoparticles is essential for making them suitable for various applications. In general, the chemical reduction method is employed for the preparation of metal nanoparticles in the liquid phase. However, complicated techniques are required to control the nanostructure during particle synthesis. The evaporation/condensation method is used for synthesizing nanoparticles in the vapor-phase. Although this method produces impurity-free particles without aggregation, very few studies have been carried out on the synthesis of composite particles in the vapor-phase. In this study, we synthesized composite nanoparticles in the vapor-phase by using the evaporation/condensation method. The results showed that bimetallic nanoparticles are produced by the evaporation/condensation method. Moreover, it was indicated that the nanostructure of the synthesized nanoparticles is influenced by the order of the electric furnace with different temperature.
关键词： nanomaterial,Plasmonic,nanoparticle synthesis in vapor phase,nanostructure,evaporation/condensation method
更新于2025-09-11 14:15:04
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3D Multi-Branched SnO2 Semiconductor Nanostructures as Optical Waveguides
摘要： Nanostructures with complex geometry have gathered interest recently due to some unusual and exotic properties associated with both their shape and material. 3D multi-branched SnO2 one-dimensional nanostructrures, characterized by a “node”—i.e., the location where two or more branches originate, are the ideal platform to distribute signals of di?erent natures. In this work, we study how this particular geometrical con?guration a?ects light propagation when a light source (i.e., laser) is focused onto it. Combining scanning electron microscopy (SEM) and optical analysis along with Raman and Rayleigh scattering upon illumination, we were able to understand, in more detail, the mechanism behind the light-coupling occurring at the node. Our experimental ?ndings show that multi-branched semiconductor 1D structures have great potential as optically active nanostructures with waveguiding properties, thus paving the way for their application as novel building blocks for optical communication networks.
关键词： SnO2,waveguiding e?ect in nanostructures,3D multi-branched nanostructures,nanowires,light scattering,tin oxide nanostructure,nano-optics
更新于2025-09-11 14:15:04
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Laser fragmentation induced defect‐rich cobalt oxide nanoparticles for electrochemical oxygen evolution reaction
摘要： Sub-5 nm cobalt oxide nanoparticles were produced in a water flowing system by pulsed laser fragmentation in liquid (PLFL). Particle fragmentation from 8 nm to 4 nm was observed and proposed to be induced by the oxidation process in water where oxidative species were present and the local temperature was rapidly elevated under laser irradiation. Significantly higher surface area, crystal phase transformation and formation of structural defects (Co2+ defects and oxygen vacancies) through the PLFL process were evidenced by a detailed structural characterization using nitrogen physisorption, electron microscopy, synchrotron X-ray diffraction and X-ray photoelectron spectroscopy. When employed as electrocatalysts for the oxygen evolution reaction under alkaline conditions, the fragmented cobalt oxides exhibited superior catalytic activity over pristine and nanocasted cobalt oxides, with delivering a current density of 10 mA/cm2 at 369 mV and a Tafel slope of 46 mV/dec, which is attributed to: (i) a larger exposed active surface area, (ii) formation of defects and iii) an increased charge transfer rate. The study provides an effective approach to engineer cobalt oxide nanostructure in a water flowing system, which shows great potential for sustainable production of active cobalt catalysts.
关键词： structural defects,cobalt oxide,nanostructure,Oxygen evolution reaction,laser fragmentation
更新于2025-09-11 14:15:04
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Monitoring subwavelength grating structures for vertical-cavity surface-emitting laser applications by spectroscopic ellipsometry
摘要： GaAs based vertical cavity surface emitting lasers (VCSELs) have one of the fastest growing markets due to their numerous applications in imaging technology, optical sensors, and interconnects. Stable, single-mode operation of these laser diodes is often achieved by forming subwavelength structures on the surface of the GaAs semiconductor. Quick and preferably noncontact inspection of the formed nanostructures is desired during the fabrication process. Nanostructure characterization by spectral ellipsometry-based metrologies has become an indispensable tool in the semiconductor industry. An advanced method of ellipsometry is the application of Mueller-matrix ellipsometry, which enables the characterization of structure details difficult to measure or not reachable by using standard ellipsometry measurements. In this paper, the authors present the results of nanostructure characterization by model-based dimension metrology using spectral ellipsometry and Mueller-matrix spectral ellipsometry of substrates during the process of VCSEL fabrication.
关键词： Mueller-matrix ellipsometry,VCSELs,spectroscopic ellipsometry,nanostructure characterization,GaAs
更新于2025-09-11 14:15:04
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Effect of Micro/Nanostructured P3HT:PCBM Surfaces on the Performance of Organic Photovoltaic Devices
摘要： In this study, the effect of periodic patterned micro/nanostructures on the active layers of thin-film organic photovoltaics (OPVs) was investigated to improve the device performance. The patterned active layer structures were fabricated by a nanoimprinting technique using different templates, including compact disc recordable (CD-R), Blu-ray disc recordable (BD-R), nanowell arrays, nanodot arrays, and honeycomb structures. The OPVs consisted of Al/nanostructured P3HT:PCBM/PEDOT:PSS/ITO. Compared with a flat reference OPV, all the micro/nanostructured OPVs exhibited higher performances, originating from enhanced light absorption due to light scattering and surface plasmon excitation at the patterned Al/P3HT:PCBM interfaces.
关键词： organic polymer solar cell,nanostructure,grating structure,nanoimprinted
更新于2025-09-11 14:15:04
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Synthesis of Plasmonic Photocatalysts for Water Splitting
摘要： Production of H2, O2, and some useful chemicals by solar water splitting is widely expected to be one of the ultimate technologies in solving energy and environmental problems worldwide. Plasmonic enhancement of photocatalytic water splitting is attracting much attention. However, the enhancement factors reported so far are not as high as expected. Hence, further investigation of the plasmonic photocatalysts for water splitting is now needed. In this paper, recent work demonstrating plasmonic photocatalytic water splitting is reviewed. Particular emphasis is given to the fabrication process and the morphological features of the plasmonic photocatalysts.
关键词： metal nanostructure,solar water splitting,surface plasmon resonance,semiconductor,metal nanoparticle
更新于2025-09-11 14:15:04
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Effect of Self-Induced Transparency in a Massive of Spherical Quantum Dots Under the Conditions of Strong Dimensional Quantization
摘要： The influence of dimensional quantization on the process of self-induced transparency in the system of spherical quantum dots in the frames of the model of the simplest interband transition in the symmetrical spherical infinitely deep wall is considered. Expressions describing the evolution of the energy of ultraviolet pulses are obtained. The relative energy losses when it becomes the 2π-pulse during propagation in a nanoscale medium, and also the polarization of the medium of non-homogeneous broadening, caused by the dispersion of radius of spherical quantum dots are obtained. The case when the radial distribution is described by the Lifshitz-Slyozov formula is considered.
关键词： quantum dot,self-induced transparency,nanostructure
更新于2025-09-11 14:15:04