Energy Absorption in Gold Nanoshells

A modeling study on energy absorption and transport in an isolated nanoshell and aggregates of nanoshells under localized surface plasma resonance (SPR) conditions is presented. A comprehensive model for multi-scattering of electromagnetic waves by a cluster of multilayered nanoshells is developed, which applies the Wigner-Eckart theorem for the calculation of the total scattering cross sessions of nanoshell aggregates. Absorption by an isolated nanoshell and by nanoshell clusters is studied using the model. Results show that the inter-nanoshell coupling results in strong field enhancement near the particle surface. Energy absorption in a nanoshell can be tuned by varying the structural parameters of the nanoshell. Smaller particles are more absorbing than the large ones, other conditions being equal. Because of the presence of a dielectric cavity, the radial distribution of the absorbed power in the metal shell may differ from the classical skin depth phenomena. The interaction among particles in close proximity causes the energy absorption efficiency and the resonance position of a nanoshell cluster to differ from those of an isolated nanoshell.

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Development of Broadband Underwater Radio Communication for Application in Unmanned Underwater Vehicles

10.20944/preprints202003.0468.v1 ◽

2020 ◽

Author(s):

Igor Smolyaninov ◽

Quirino Balzano ◽

Dendy Young

Keyword(s):

Electromagnetic Waves ◽

Impedance Matching ◽

Field Enhancement ◽

Underwater Vehicles ◽

Skin Depth ◽

Radio Waves ◽

Radio Communication ◽

Propagation Length ◽

Unmanned Underwater Vehicles ◽

Surface Electromagnetic Waves

This paper presents several novel designs of underwater portable radio antennas operating in the 2 MHz, 50 MHz and 2.4 GHz bands and efficient for launching surface electromagnetic waves at the seawater/air interface. The antenna operation is enabled by an impedance matching antenna enclosure, which is filled with de-ionized water. Enhanced coupling to surface electromagnetic waves is based on the field enhancement at the antenna tip. These design features allow us to reduce antenna dimensions and improve the coupling of electromagnetic energy to the surrounding saltwater medium. Since surface wave propagation length far exceeds the skin depth of conventional radio waves at the same frequency, this technique is useful for broadband underwater wireless communication over distances, which far exceed the skin depth in seawater. We conclude that the developed broadband underwater radio communication technique will be useful in networking of unmanned underwater vehicles.

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Study on Negative Poisson Ratio and Energy Absorption Characteristics of Embedded Arrow Honeycomb Structure

Advances in Sciences and Engineering ◽

10.32732/ase.2020.12.2.47 ◽

2020 ◽

Vol 12 (2) ◽

pp. 47-57

Author(s):

Wenzheng Liu ◽

Shiqing Huang ◽

Jiachu Xu

Keyword(s):

Energy Absorption ◽

Poisson’S Ratio ◽

Poisson Ratio ◽

Structural Parameters ◽

Impact Resistance ◽

Honeycomb Structure ◽

Absorption Efficiency ◽

Poisson's Ratio ◽

Negative Poisson’S Ratio ◽

Negative Poisson's Ratio

Impact collision exists widely in people's daily life and threatens people's life safety. Negative Poisson's ratio structure has good mechanical properties. Therefore, it is of great significance to design and study the energy absorption structure with negative Poisson's ratio effect. Based on the traditional symmetrical concave honeycomb structure (SCHS) with negative Poisson's ratio, two modified negative Poisson's ratio honeycomb structures are proposed by adding embedded straight rib arrow structure and embedded curved rib arrow structure, which are respectively called embedded straight rib arrow honeycomb structure (SRAH) and embedded curved rib arrow honeycomb structure (CRAH). Through finite element simulation experiment, the negative Poisson's ratio characteristics of two cellular cells were studied and the influence of structural parameters of the cells on the Poisson's ratio was discussed. ANSYS/LS-DYNA was used to analyze the energy absorption of the proposed three cellular structures at different impact velocities. Numerical simulation results show that the SRHS and CRAH have greater stress platform value, specific energy absorption and impact force efficiency than SCHS, indicating that the SRAH and CRAH exhibited better energy absorption efficiency and impact resistance performance.

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Optically Induced Field-Emission Source Based on Aligned Vertical Carbon Nanotube Arrays

Nanomaterials ◽

10.3390/nano11071810 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1810

Author(s):

Mengjie Li ◽

Qilong Wang ◽

Ji Xu ◽

Jian Zhang ◽

Zhiyang Qi ◽

...

Keyword(s):

Carbon Nanotube ◽

Electric Field ◽

Field Emission ◽

Field Enhancement ◽

Absorption Efficiency ◽

Photon Absorption ◽

Nanotube Arrays ◽

Carbon Nanotube Arrays ◽

Induced Field ◽

Optically Induced

Due to the high field enhancement factor and photon-absorption efficiency, carbon nanotubes (CNTs) have been widely used in optically induced field-emission as a cathode. Here, we report vertical carbon nanotube arrays (VCNTAs) that performed as high-density electron sources. A combination of high applied electric field and laser illumination made it possible to modulate the emission with laser pulses. When the bias electric field and laser power density increased, the emission process is sensitive to a power law of the laser intensity, which supports the emission mechanism of optically induced field emission followed by over-the-barrier emission. Furthermore, we determine a polarization dependence that exhibits a cosine behavior, which verifies the high possibility of optically induced field emission.

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Terahertz quantum plasmonics at nanoscales and angstrom scales

Nanophotonics ◽

10.1515/nanoph-2019-0436 ◽

2020 ◽

Vol 9 (2) ◽

pp. 435-451 ◽

Cited By ~ 1

Author(s):

Taehee Kang ◽

Young-Mi Bahk ◽

Dai-Sik Kim

Keyword(s):

Electron Tunneling ◽

Strong Field ◽

Field Enhancement ◽

Dipole Antenna ◽

Strong Light ◽

Metallic Structures ◽

Terahertz Pulses ◽

Matter Interaction ◽

Light Matter Interaction ◽

Quantum Phenomena

AbstractThrough the manipulation of metallic structures, light–matter interaction can enter into the realm of quantum mechanics. For example, intense terahertz pulses illuminating a metallic nanotip can promote terahertz field–driven electron tunneling to generate enormous electron emission currents in a subpicosecond time scale. By decreasing the dimension of the metallic structures down to the nanoscale and angstrom scale, one can obtain a strong field enhancement of the incoming terahertz field to achieve atomic field strength of the order of V/nm, driving electrons in the metal into tunneling regime by overcoming the potential barrier. Therefore, designing and optimizing the metal structure for high field enhancement are an essential step for studying the quantum phenomena with terahertz light. In this review, we present several types of metallic structures that can enhance the coupling of incoming terahertz pulses with the metals, leading to a strong modification of the potential barriers by the terahertz electric fields. Extreme nonlinear responses are expected, providing opportunities for the terahertz light for the strong light–matter interaction. Starting from a brief review about the terahertz field enhancement on the metallic structures, a few examples including metallic tips, dipole antenna, and metal nanogaps are introduced for boosting the quantum phenomena. The emerging techniques to control the electron tunneling driven by the terahertz pulse have a direct impact on the ultrafast science and on the realization of next-generation quantum devices.

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Energy Absorption of Origami Crash Box: Numerical Simulation and Theoretical Analysis

Volume 5B: 42nd Mechanisms and Robotics Conference ◽

10.1115/detc2018-86261 ◽

2018 ◽

Cited By ~ 1

Author(s):

Mengyan Shi ◽

Jiayao Ma ◽

Yan Chen ◽

Zhong You

Keyword(s):

Energy Absorption ◽

Theoretical Study ◽

Low Cost ◽

Deformation Mode ◽

Absorption Efficiency ◽

Great Promise ◽

Good Match ◽

Energy Absorption Efficiency ◽

Thin Walled ◽

Initial Peak

Thin-walled tubes as energy absorption devices are widely in use for their low cost and high manufacturability. Employing origami technique on a tube enables induction of a predetermined failure mode so as to improve its energy absorption efficiency. Here we study the energy absorption of a hexagonal tubular device named the origami crash box numerically and theoretically. Numerical simulations of the quasi-static axial crushing show that the pattern triggers a diamond-shaped mode, leading to a substantial increase in energy absorption and reduction in initial peak force. The effects of geometric parameters on the performance of the origami crash box are also investigated through a parametric study. Furthermore, a theoretical study on the deformation mode and energy absorption of the origami crash box is carried out, and a good match with numerical results is obtained. The origami crash box shows great promise in the design of energy absorption devices.

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Bending Behavior of Simply-Supported Sandwich Beams Subjected to Large Deflection

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.777.569 ◽

2018 ◽

Vol 777 ◽

pp. 569-574

Author(s):

Zhong You Xie

Keyword(s):

Energy Absorption ◽

Large Deflection ◽

Absorption Efficiency ◽

Sandwich Beams ◽

Element Simulation ◽

Energy Absorption Efficiency ◽

Load Carrying ◽

Absorption Performance ◽

Bending Behavior ◽

The Moment

Due to thin skins and soft core, it is apt to local indentation inducing the concurrence of geometrical and material nonlinearity in sandwich structures. In the paper, finite element simulation is used to investigate the bending behavior of lightweight sandwich beams under large deflection. A modified formulation for the moment at mid-span section of sandwich beams under large deflection is presented, and energy absorption performance is assessed based on energy absorption efficiency. In addition, it is found that no local indentation arises initially, while later that increases gradually with loading displacement increasing. The height of the mid-span section as well as load-carrying capacity decreases significantly with local indentation depth increasing.

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Formation, Optical Properties and Applications of Edge Gold-Coated Silver Nanoprisms

MRS Proceedings ◽

10.1557/opl.2015.581 ◽

2015 ◽

Vol 1737 ◽

Author(s):

Mohammad M. Shahjamali ◽

Michael Salvador ◽

Negin Zaraee

Keyword(s):

High Stability ◽

Light Harvesting ◽

Strong Field ◽

Field Enhancement ◽

Localized Surface Plasmon ◽

High Yield ◽

Bulk Heterojunctions ◽

Silver Nanoprisms ◽

Photovoltaic Applications ◽

Microscopic Techniques

ABSTRACTA facile, high-yield synthesis of edge gold-coated silver nanoprisms (GSNPs) with a gold nanoframe as thin as 1.7 nm and their comprehensive characterizations by using various spectroscopic and microscopic techniques is introduced. The GSNPs exhibit remarkably higher stability than silver nanoprisms (SNPs) and are therefore explored as effective optical antennae for light-harvesting applications. When embedded into a bulk heterojunctions film of P3HT:PCBM, plasmonic GSNPs with a localized surface plasmon resonance (LSPR) around 500 nm can effectively act as optical antennae to enhance light harvesting in the active layer. As a result, we measured up to 7-fold enhancement in the polaron generation yield through photoinduced absorption spectroscopy. Owing to the high stability and strong field enhancement, the presented GSNPs feature great potential as plasmonic probes for photovoltaic applications and LSPR sensing.

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Preparation and Characterization of Gradient Compressed Porous Metal for High-Efficiency and Thin-Thickness Acoustic Absorber

Materials ◽

10.3390/ma12091413 ◽

2019 ◽

Vol 12 (9) ◽

pp. 1413 ◽

Cited By ~ 6

Author(s):

Xiaocui Yang ◽

Xinmin Shen ◽

Panfeng Bai ◽

Xiaohui He ◽

Xiaonan Zhang ◽

...

Keyword(s):

Sound Absorption ◽

High Efficiency ◽

Structural Parameters ◽

Porous Metal ◽

Theoretical Models ◽

Absorption Efficiency ◽

Total Thickness ◽

Porous Metals ◽

Absorption Coefficients ◽

Optimal Average

Increasing absorption efficiency and decreasing total thickness of the acoustic absorber is favorable to promote its practical application. Four compressed porous metals with compression ratios of 0%, 30%, 60%, and 90% were prepared to assemble the four-layer gradient compressed porous metals, which aimed to develop the acoustic absorber with high-efficiency and thin thickness. Through deriving structural parameters of thickness, porosity, and static flow resistivity for the compressed porous metals, theoretical models of sound absorption coefficients of the gradient compressed porous metals were constructed through transfer matrix method according to the Johnson–Champoux–Allard model. Sound absorption coefficients of four-layer gradient compressed porous metals with the different permutations were theoretically analyzed and experimentally measured, and the optimal average sound absorption coefficient of 60.33% in 100–6000 Hz was obtained with the total thickness of 11 mm. Sound absorption coefficients of the optimal gradient compressed porous metal were further compared with those of the simple superposed compressed porous metal, which proved that the former could obtain higher absorption efficiency with thinner thickness and fewer materials. These phenomena were explored by morphology characterizations. The developed high-efficiency and thin-thickness acoustic absorber of gradient compressed porous metal can be applied in acoustic environmental detection and industrial noise reduction.

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