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Enhancement of local electromagnetic fields by periodic optical resonators
摘要： The periodically profiled metasurfaces of silicon and of the same surfaces coated with a thin layer of silver are experimentally investigated to improve the signal-to-noise ratio in the observation of Raman light scattering from molecular compounds. The noise in this case is the unavoidable background molecular luminescence. Our experimental and computer simulation data demonstrate an anomalous optical response due to the excitation of metal-dielectric surface resonances. An enhanced Raman scattering signal is observed from 5,5'-dithiobis(2-nitrobenzoic) acid (DTNB) organic molecules deposited on the metasurface. The proposed metasurface provides a significant enhancement of the RS signal in comparison with the luminescence signal and is an efficient substrate for realising giant Raman scattering of light.
关键词： silicon,metasurface,dielectric resonators,nanostructures,plasmon resonance,giant Raman scattering of light
更新于2025-09-23 15:23:52
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Panorama of boron nitride nanostructures via lamp ablation
摘要： A diverse range of remarkable boron nitride (BN) nanostructures subsuming nano-horns, nano-rods, nano-platelets, and clusters of hollow nanospheres (nano-onions, arguably of greatest applied and fundamental interest) have been produced exclusively from crystalline BN precursor powder via lamp ablation. The procedure is safe, devoid of toxic reagents, simple, rapid and scalable—generating some genres of nanoparticles that had previously proved elusive. Product structure and composition were unambiguously assessed by high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy.
关键词： lamp ablation,non-toxic,boron nitride,nanostructures,nano-onions
更新于2025-09-23 15:23:52
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Spectral and third order nonlinear optical properties of Yttrium-doped BaWO4 nanostructures
摘要： BaWO4 nanostructures doped with different concentrations of Yttrium have been synthesized by a chemical method. The as-prepared samples were characterized by UV–vis diffuse reflectance spectra, X-ray diffraction, Fourier transform infrared spectroscopy, Transmission electron microscopy and Raman spectra. From the UV–vis spectra, it is seen that absorption band edge shifted towards the visible region upon Y doping. The X-ray diffraction and Raman analyses reveal that the BaWO4 powders present a tetragonal structure. The third-order nonlinear optical responses of BaWO4 nanostructures on the effect of Y concentrations was investigated by Z-scan technique using a continuous wave Nd:YAG laser at 532 nm. Experimental results have shown that the observed nonlinear absorption and nonlinear refraction behavior is attributed to saturable absorption and thermal nonlinear effects.
关键词： Nanostructures,Yttrium,Saturable absorption,Z-scan
更新于2025-09-23 15:23:52
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Cu(OH)2 Nanostructures for Dynamic Photodegradation of Methyl Orange under Visible Light
摘要： A new material of Cu(OH)2 nanostructures was prepared using cupric nitrate and sodium hydroxide as raw materials by the chemical precipitation method. The Cu(OH)2 nanostructures were characterized by scanning electron microscope, transmission electron microscopy, infrared spectrometer, and X-ray diffractometer. The results showed that the Cu(OH)2 nanostructures exhibited excellent uniform and dispersion at 40°C. A series of factors was investigated to effect the photocatalytic efficiency of methyl orange (MO), such as the concentration of Cu(OH)2 nanostructures, the reaction time of the Cu(OH)2 nanostructures, the initial concentration of MO, and so on. As a result, the Cu(OH)2 nanostructures exhibited excellent photocatalytic efficiency with the concentration of 20 mg L–1 Cu(OH)2 nanostructures, the initial concentration of MO was 15 mg L–1 and the stirring time was 70 min.
关键词： photocatalytic efficiency,chemical precipitation method,Cu(OH)2 nanostructures
更新于2025-09-23 15:22:29
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Metallic Nanostructures for Multispectral Filters
摘要： A metal-dielectric-metal structure with cross-shaped-hole array in metal thin films is studied for plasmonic multispectral filters, which covers visible to near-infrared wavelengths. Surface plasmons are induced from incident wave by a periodic array of nanostructures, then the localized surface plasmon polaritons oscillate in the cavity, which is formed by the two layers of metals through near-field excitation. The transmission spectrum of the metal-dielectric-metal structure with cross-shaped-hole array is investigated with the finite-difference time-domain method; our simulations show that the features of the hole, and the refractive index and the thickness of the dielectric layer all affect the optical spectral performance. This metal-dielectric-metal structure provides additional flexibility in tuning transmission spectrum due to its Fabry-Perot cavity property. Our study shows that it is possible to obtain desired multispectral filters by programming the refractive index and thickness of the dielectric layer, and these parameters of the metallic structures.
关键词： Surface Plasmon,Metallic Nanostructures,Multispectral Filters
更新于2025-09-23 15:22:29
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GeO <sub/>2</sub> Encapsulated Ge Nanostructure with Enhanced Lithium-Storage Properties
摘要： Germanium (Ge)-based nanostructures, especially those with germanium dioxide (GeO2), have drawn great interest for applications in lithium (Li)-ion batteries due to their ultrahigh theoretical Li+ storage capability (8.4 Li/Ge). However, GeO2 in conventional Ge(s)/GeO2(c) (where (c) means the core and (s) means the shell) composite anodes with Ge shell outside GeO2 undergoes an irreversible conversion reaction, which restricts the maximum capacity of such batteries to 1126 mAhg?1 (the equivalent of storing 4.4 Li+). In this work, a porous GeO2(s)/Ge(c) nanostructure with GeO2 shell outside Ge cores are successfully fabricated utilizing the Kirkendall effect and used as a lithium-ion battery anode, giving a substantially improved capacity of 1333.5 mAhg?1 at a current density of 0.1 Ag?1 after 30 cycles and a stable long-time cycle performance after 100 cycles at a current density of 0.5 A g?1. The enhanced battery performance is attributed to the improved reversibility of GeO2 lithiation/delithiation processes catalyzed by Ge in the properly structured porous GeO2(s)/Ge(c) nanostructure.
关键词： porous,Kirkendall effect,nanostructures,lithium ion batteries,GeO2(s)/Ge(c)
更新于2025-09-23 15:22:29
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Fabrication and Photoluminescence Properties of Monodispersed SiO2@SrAl2Si2O8:Eu2+ Core-Shell Submicron Spheres
摘要： Nanocrystalline SrAl2Si2O8:Eu2+ phosphor layers were coated on the surface of preformed submicron silica spheres by sol-gel method. The resulted monodispersed SiO2@SrAl2Si2O8:Eu2+ core-shell submicron spherical phosphors were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and photoluminescence spectra. The XRD results demonstrated that the SrAl2Si2O8:Eu2+ layers began to crystallize on the SiO2 spheres at 900 °C and the crystallinity increased with raising the annealing temperature. The obtained monodispersed core-shell spherical phosphors have perfect spherical shape with narrow size distribution (average size 500 nm). The Eu2+ shows a strong photoluminescence (dominated by 4f65d1 → 4f7 red emission at 390 nm) due to an efficient energy transfer from vanadate groups to Eu2+. The photoluminescence intensity of Eu2+ increases with raising the annealing temperature.
关键词： Nanostructures,Sol-gel processes,Optical properties,X-ray diffraction,Phosphers
更新于2025-09-23 15:22:29
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</sub> ) Interlayer
摘要： Electrical and dielectric properties of Au/n-Si metal–semiconductor structures with high dielectric have been examined by capacitance/conductance–voltage (C/G–V) measurements in the frequency range of 5–500 kHz at room temperature. Voltage-dependent profiles of interface states (Nss) and resistance (Ri) were extracted from the C and G data using the low–high-frequency capacitance and Nicollian–Brews methods, respectively. The real and imaginary components of the complex dielectric constant (ε', ε''), electric modulus (M', M''), and ac conductivity (σac) were calculated from the C and G data. All parameters have a strong relation with frequency and voltage, especially at low frequencies due to Maxwell–Wagner relaxation and Nss. The observed peaks in the Nss–V and Ri–V plots can be ascribed by the special distribution of Nss at M/S interface. These results confirmed that [2% graphene cobalt-doped (Ca3Co4Ga0.001Ox)] interlayer has high-dielectric constant and can be used an interlayer instead of the traditional SiO2 at M/S interface to increase their capacitance or more charges/energy storage and reduce both the values of Nss and series resistance (Rs). The values of σ are almost constant at lower–intermediate frequencies, but they start to increase at high frequencies that are corresponding to the dc and ac conductivity, respectively.
关键词： electrical properties,nanostructures,Dielectric properties,graphene,polymer
更新于2025-09-23 15:22:29
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Nanoporous water oxidation electrodes with a low loading of laser-deposited Ru/C exhibit enhanced corrosion stability
摘要： For the oxidation of water to dioxygen, oxide-covered ruthenium metal is known as the most efficient catalyst, however, with limited stability. Herein, we present a strategy for incorporating a Ru/C composite onto a novel nanoporous electrode surface with low noble metal loading and improved stability. The Ru/C is coated on the pore walls of anodic alumina templates in a one-step laser-induced deposition method from Ru3(CO)12 solutions. Scanning electron microscopy proves the presence of a continuous Ru/C layer along the inner pore walls. The amorphous material consists of metallic Ru incorporated in a carbonaceous C matrix as shown by X-ray diffraction combined with Raman and X-ray photoelectron spectroscopies. These porous electrodes reveal enhanced stability during water oxidation as compared to planar samples at pH 4. Finally, their electrocatalytic performance depends on the geometric parameters and is optimized with 13 μm pore length, which yields 2.6 mA cm?2, or 49 A g?1, at η = 0.20 V.
关键词： ruthenium catalyst,nanostructures,water splitting,electrochemistry,noble metals
更新于2025-09-23 15:22:29
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Solvent effect on the morphology of the bee: structure observed by atomic force microscopy on bitumen sample
摘要： The objective of this work was to characterize the asphaltic cement penetration grade 30/45 (CAP 30/45) based on the morphology of nanostructures called 'bee' structure observed and its modification when the binder was diluted in heptanes or toluene. The morphology of CAP30/45, toluene and heptane films was studied by Atomic Force Microscopy (AFM) tapping mode and showed typical 'bee' structure in asphaltic cement films, but this structure is not visible on the other films. While, toluene completely dissolved the bees, films attacked with heptane still presented some structures left.
关键词： nanostructures,AFM,asphaltene,bitumen
更新于2025-09-23 15:22:29