scholarly journals Strong Modulations of Optical Reflectance in Tapered Core–Shell Nanowires

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3572 ◽  
Author(s):  
Francesco Floris ◽  
Lucia Fornasari ◽  
Vittorio Bellani ◽  
Andrea Marini ◽  
Francesco Banfi ◽  
...  
Keyword(s):  
Incident Angle ◽  
Core Shell ◽  
Specular Reflectance ◽  
Sensing Applications ◽  
Reflected Light ◽  
Geometrical Features ◽  
Wide Range ◽  
Vertically Aligned ◽  
Reflectance Measurements ◽  
Shell Nanowires

Random assemblies of vertically aligned core–shell GaAs–AlGaAs nanowires displayed an optical response dominated by strong oscillations of the reflected light as a function of the incident angle. In particular, angle-resolved specular reflectance measurements showed the occurrence of periodic modulations in the polarization-resolved spectra of reflected light for a surprisingly wide range of incident angles. Numerical simulations allowed for identifying the geometrical features of the core–shell nanowires leading to the observed oscillatory effects in terms of core and shell thickness as well as the tapering of the nanostructure. The present results indicate that randomly displaced ensembles of nanoscale heterostructures made of III–V semiconductors can operate as optical metamirrors, with potential for sensing applications.

Vertically aligned ZnO–ZnGa2O4 core–shell nanowires: from synthesis to optical properties

2012 ◽  
Vol 14 (4) ◽  
Author(s):  
Miao Zhong ◽  
Yanbo Li ◽  
Takero Tokizono ◽  
Maojun Zheng ◽  
Ichiro Yamada ◽  
...  
Keyword(s):  
Optical Properties ◽  
Core Shell ◽  
Vertically Aligned ◽  
Shell Nanowires

Well-ordered vertically aligned ZnO/CdS core/shell nanowires with enhanced photocatalytic performance

2017 ◽  
Vol 320 ◽  
pp. 467-471 ◽  
Author(s):  
Guifeng Chen ◽  
Xiaolin Song ◽  
Hui Zhang ◽  
Xuenan Zhang ◽  
Jiao Zhang ◽  
...  
Keyword(s):  
Photocatalytic Performance ◽  
Core Shell ◽  
Vertically Aligned ◽  
Shell Nanowires

Selective-area growth of vertically aligned GaAs and GaAs/AlGaAs core–shell nanowires on Si(111) substrate

2009 ◽  
Vol 20 (14) ◽  
pp. 145302 ◽  
Author(s):  
Katsuhiro Tomioka ◽  
Yasunori Kobayashi ◽  
Junichi Motohisa ◽  
Shinjiroh Hara ◽  
Takashi Fukui
Keyword(s):  
Core Shell ◽  
Selective Area Growth ◽  
Selective Area ◽  
Area Growth ◽  
Vertically Aligned ◽  
Shell Nanowires

A SCALE-BASED MODEL OF REFLECTIVITY

Fractals ◽  
1994 ◽  
Vol 02 (03) ◽  
pp. 413-416 ◽  
Author(s):  
E. MICHAEL SHIPULSKI ◽  
CHRISTOPHER A. BROWN
Keyword(s):  
Computer Simulation ◽  
Patch Size ◽  
Specular Reflection ◽  
Incident Angle ◽  
Incident Light ◽  
Design Evaluation ◽  
Patch Area ◽  
Interaction Models ◽  
Specular Reflectance ◽  
Reflectance Measurements

A computer simulation is described that models reflectivity as a set of discrete interactions, represented by perfectly reflecting, triangular mirrors fit to the surface using the patchwork method.1 The model is based on a premise that topographically dependent phenomena, such as reflectivity, interact with surfaces over certain scales and that these interaction scales can be used to characterize the interactions for use in the design evaluation of reflective topographies. The simulation is performed on a reflective topography and the results are discussed. Results from the simulation, plots of degree of specular reflection versus patch area, or scale, show that modeling the surface as a collection of mirrors of decreasing size results in less light reflected in the specular direction, or more scattering. Increased scattering from a reduction in patch size, or size of the interaction, models the increased scattering due to a reduction in wavelength of the incident light and reduced scattering due to an increase in incident angle, both shown experimentally in specular reflectance measurements.

One-Dimensional TiO2@GaON Core-Shell Nanowires with Controlled Shell Thickness from Atomic Layer Deposition for Stable and Efficient Photoelectrochemical Water Splitting

2019 ◽  
Author(s):  
Jiajia Tao ◽  
Hong-Ping Ma ◽  
Kaiping Yuan ◽  
Yang Gu ◽  
Jianwei Lian ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Band Gap ◽  
Water Splitting ◽  
Atomic Layer ◽  
Photoelectrochemical Water Splitting ◽  
Core Shell ◽  
Photoelectrochemical Performance ◽  
Highly Efficient ◽  
Layer Deposition ◽  
Shell Nanowires

<div>As a promising oxygen evolution reaction semiconductor, TiO2 has been extensively investigated for solar photoelectrochemical water splitting. Here, a highly efficient and stable strategy for rationally preparing GaON cocatalysts on TiO2 by atomic layer deposition is demonstrated, which we show significantly enhances the</div><div>photoelectrochemical performance compared to TiO2-based photoanodes. For TiO2@20 nm-GaON core-shell nanowires a photocurrent density up to 1.10 mA cm-2 (1.23 V vs RHE) under AM 1.5 G irradiation (100 mW cm-2) has been achieved, which is 14 times higher than that of TiO2 NWs. Furthermore, the oxygen vacancy formation on GaON as well as the band gap matching with TiO2 not only provides more active sites for water oxidation but also enhances light absorption to promote interfacial charge separation and migration. Density functional theory studies of model systems of GaON-modified TiO2 confirm the band gap reduction, high reducibility and ability to activate water. The highly efficient and stable systems of TiO2@GaON core-shell nanowires provide a deeper understanding and universal strategy for enhancing photoelectrochemical performance of photoanodes now available. </div>

scholarly journals Strain Sensor via Wood Anomalies in 2D Dielectric Array

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1022
Author(s):  
Rashid G. Bikbaev ◽  
Ivan V. Timofeev ◽  
Vasiliy F. Shabanov
Keyword(s):  
Higher Plants ◽  
Numerical Study ◽  
Reciprocal Lattice ◽  
Strain Sensing ◽  
Photonic Materials ◽  
Sensing Applications ◽  
Wide Range ◽  
Sensor Structure ◽  
Optical Behavior ◽  
Chlorophyll Absorption

Optical sensing is one of many promising applications for all-dielectric photonic materials. Herein, we present an analytical and numerical study on the strain-responsive spectral properties of a bioinspired sensor. The sensor structure contains a two-dimensional periodic array of dielectric nanodisks to mimic the optical behavior of grana lamellae inside chloroplasts. To accumulate a noticeable response, we exploit the collective optical mode in grana ensemble. In higher plants, such a mode appears as Wood’s anomaly near the chlorophyll absorption line to control the photosynthesis rate. The resonance is shown persistent against moderate biological disorder and deformation. Under the stretching or compression of a symmetric structure, the mode splits into a couple of polarized modes. The frequency difference is accurately detected. It depends on the stretch coefficient almost linearly providing easy calibration of the strain-sensing device. The sensitivity of the considered structure remains at 5 nm/% in a wide range of strain. The influence of the stretching coefficient on the length of the reciprocal lattice vectors, as well as on the angle between them, is taken into account. This adaptive phenomenon is suggested for sensing applications in biomimetic optical nanomaterials.

scholarly journals Broadband Meta‐Absorber with Au/Ni Core–Shell Nanowires for Solar Vapor Generator

2021 ◽  
Vol 5 (7) ◽  
pp. 2100185
Author(s):  
Soomin Son ◽  
Jaemin Park ◽  
Sucheol Ju ◽  
Daihong Huh ◽  
Junho Jun ◽  
...  
Keyword(s):  
Core Shell ◽  
Vapor Generator ◽  
Shell Nanowires

scholarly journals Femtosecond Laser Fabrication of Hybrid Metal-Dielectric Structures with Nonlinear Photoluminescence

Photonics ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 121
Author(s):  
Ekaterina Ponkratova ◽  
Eduard Ageev ◽  
Filipp Komissarenko ◽  
Sergei Koromyslov ◽  
Dmitry Kudryashov ◽  
...  
Keyword(s):  
Visible Spectral Region ◽  
Single Step ◽  
Hybrid Nanostructures ◽  
Nonlinear Properties ◽  
Nanophotonic Devices ◽  
Sensing Applications ◽  
Structure Morphology ◽  
Wide Range ◽  
Nonlinear Signal ◽  
Dielectric Structures

Fabrication of hybrid micro- and nanostructures with a strong nonlinear response is challenging and represents a great interest due to a wide range of photonic applications. Usually, such structures are produced by quite complicated and time-consuming techniques. This work demonstrates laser-induced hybrid metal-dielectric structures with strong nonlinear properties obtained by a single-step fabrication process. We determine the influence of several incident femtosecond pulses on the Au/Si bi-layer film on produced structure morphology. The created hybrid systems represent isolated nanoparticles with a height of 250–500 nm exceeding the total thickness of the Au-Si bi-layer. It is shown that fabricated hybrid nanostructures demonstrate enhancement of the SHG signal (up to two orders of magnitude) compared to the initial planar sample and a broadband photoluminescence signal (more than 200 nm in width) in the visible spectral region. We establish the correlation between nonlinear signal and phase composition provided by Raman scattering measurements. Such laser-induced structures have significant potential in optical sensing applications and can be used as components for different nanophotonic devices.

scholarly journals Synthesis and Advanced Characterization of Polymer-Protein Core-Shell Nanoparticles

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 730
Author(s):  
Erik Sarnello ◽  
Tao Li
Keyword(s):  
Particle Size ◽  
Small Angle ◽  
Core Shell ◽  
Assembly Process ◽  
Shell Nanoparticles ◽  
X Ray ◽  
X Ray Scattering ◽  
Wide Range ◽  
Core Shell Nanoparticles ◽  
Ray Scattering

Enzyme immobilization techniques are widely researched due to their wide range of applications. Polymer–protein core–shell nanoparticles (CSNPs) have emerged as a promising technique for enzyme/protein immobilization via a self-assembly process. Based on the desired application, different sizes and distribution of the polymer–protein CSNPs may be required. This work systematically studies the assembly process of poly(4-vinyl pyridine) and bovine serum albumin CSNPs. Average particle size was controlled by varying the concentrations of each reagent. Particle size and size distributions were monitored by dynamic light scattering, ultra-small-angle X-ray scattering, small-angle X-ray scattering and transmission electron microscopy. Results showed a wide range of CSNPs could be assembled ranging from an average radius as small as 52.3 nm, to particles above 1 µm by adjusting reagent concentrations. In situ X-ray scattering techniques monitored particle assembly as a function of time showing the initial particle growth followed by a decrease in particle size as they reach equilibrium. The results outline a general strategy that can be applied to other CSNP systems to better control particle size and distribution for various applications.

scholarly journals A Nanoplasmonic-Based Biosensing Approach for Wide-Range and Highly Sensitive Detection of Chemicals

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1961
Author(s):  
Francesco Arcadio ◽  
Luigi Zeni ◽  
Aldo Minardo ◽  
Caterina Eramo ◽  
Stefania Di Di Ronza ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Limit Of Detection ◽  
Slab Waveguide ◽  
Grating Pattern ◽  
Transparent Substrate ◽  
Synthetic Receptor ◽  
Sensing Applications ◽  
Wide Range ◽  
Plastic Optical Fibers ◽  
Highly Sensitive Detection

In a specific biosensing application, a nanoplasmonic sensor chip has been tested by an experimental setup based on an aluminum holder and two plastic optical fibers used to illuminate and collect the transmitted light. The studied plasmonic probe is based on gold nanograting, realized on the top of a Poly(methyl methacrylate) (PMMA) chip. The PMMA substrate could be considered as a transparent substrate and, in such a way, it has been already used in previous work. Alternatively, here it is regarded as a slab waveguide. In particular, we have deposited upon the slab surface, covered with a nanograting, a synthetic receptor specific for bovine serum albumin (BSA), to test the proposed biosensing approach. Exploiting this different experimental configuration, we have determined how the orientation of the nanostripes forming the grating pattern, with respect to the direction of the input light (longitudinal or orthogonal), influences the biosensing performances. For example, the best limit of detection (LOD) in the BSA detection that has been obtained is equal to 23 pM. Specifically, the longitudinal configuration is characterized by two observable plasmonic phenomena, each sensitive to a different BSA concentration range, ranging from pM to µM. This aspect plays a key role in several biochemical sensing applications, where a wide working range is required.

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