Anomalous forward scattering of gain-assisted dielectric shell-coated metallic core spherical particles

AbstractWe have investigated the scattering properties of an individual core-shell nanoparticle using the Mie theory, which can be tuned to support both electric and magnetic modes simultaneously. In general, the suppression of forward scattering can be realized by the second Kerker condition. Here, a novel mechanism has to be adopted to explain zero-forward scattering, which originates from the complex interactions between dipolar and quadrupolar modes. However, for lossy and lossless core-shell spherical nanoparticles, zero-forward scattering can never be achieved because the real parts of Mie expansion coefficients are always positive. By adding proper gain in dielectric shell, zero-forward scattering can be found at certain incident wavelengths, which means that all electric and magnetic responses in Mie scattering can be counteracted totally in the forward direction. In addition, if the absolute values of dipolar and quadrupolar terms are in the same order of magnitude, the local scattering minimum and maximum can be produced away from the forward and backward directions due to the interacting effect between the dipolar and quadrupolar terms. Furthermore, by adding suitable gain in shell, super-forward scattering can also be realized at certain incident wavelengths. We also demonstrated that anomalously weak scattering or superscattering could be obtained for the core-shell nanoparticles with suitable gain in shell. In particular, for such a choice of suitable gain in shell, we can obtain zero-forward scattering and anomalously weak scattering at the same wavelength as well as super-forward scattering at another wavelength. These features may provide new opportunities for cloaking, plasmonic lasers, optical antennas, and so on.

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Ultra-directional forward scattering by individual core-shell nanoparticles

Optics Express ◽

10.1364/oe.22.016178 ◽

2014 ◽

Vol 22 (13) ◽

pp. 16178 ◽

Cited By ~ 109

Author(s):

Wei Liu ◽

Jianfa Zhang ◽

Bing Lei ◽

Haotong Ma ◽

Wenke Xie ◽

...

Keyword(s):

Forward Scattering ◽

Core Shell ◽

Shell Nanoparticles ◽

Core Shell Nanoparticles ◽

Individual Core

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Broadband zero-backward and near-zero-forward scattering by metallo-dielectric core-shell nanoparticles

Scientific Reports ◽

10.1038/srep12491 ◽

2015 ◽

Vol 5 (1) ◽

Cited By ~ 34

Author(s):

Yan Li ◽

Mingjie Wan ◽

Wenyang Wu ◽

Zhuo Chen ◽

Peng Zhan ◽

...

Keyword(s):

Forward Scattering ◽

Core Shell ◽

Shell Nanoparticles ◽

Core Shell Nanoparticles

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Design of Bistable Gold@Spin-Crossover Core-Shell Nanoparticles Showing Large Electrical Responses for the Spin Switching

10.26434/chemrxiv.7543121 ◽

2019 ◽

Author(s):

Ramón Torres-Cavanillas ◽

Rocher Sanchis-Gual ◽

Julien Dugay ◽

Marc Coronado-Puchau ◽

Dr. Mónica Giménez Marqués ◽

...

Keyword(s):

Spin Crossover ◽

Thermal Hysteresis ◽

Spin Transition ◽

Hysteresis Loops ◽

Large Change ◽

Core Shell ◽

Shell Nanoparticles ◽

Simple Protocol ◽

Order Of Magnitude ◽

Core Shell Nanoparticles

A simple protocol to prepare core-shell gold@spin-crossover (Au@SCO) nanoparticles (NPs) based on the 1D spin-crossover [Fe(Htrz)2(trz)](BF4) coordination polymer is reported. The synthesis relies on a two-step approach consisting on a partial surface ligand substitution of the citrate-stabilized Au NPs followed by the controlled growth of a very thin layer of the SCO polymer. As a result, colloidally stable core@shell spherical NPs of 19 nm in size exhibiting a narrow distribution in sizes have been obtained, revealing a switchable SCOshell of ca.4 nm. Temperature-dependent charge transport measurements of an electrical device based on assemblies of these Au@SCO NPs display well-defined, reproducible and sharp thermal hysteresis loops in the conductance near room temperature. This device is characterized both, by a large change in conductance upon spin state switching, and a remarkable transition abruptness, as compared with other memory devices based on the pristine SCO NPs. As a result, the sensitivity of the device to the spin transition is dramatically improved, with values for the ON/OFF ratio which are an order of magnitude better than the best ones obtained in previous SCO devices.

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Enhanced light trapping in thin film solar cells by Ag/Al2O3 core-shell nanoparticles

Modern Physics Letters B ◽

10.1142/s0217984914500407 ◽

2014 ◽

Vol 28 (05) ◽

pp. 1450040 ◽

Cited By ~ 2

Author(s):

Feng-Xiang Chen ◽

Li-Sheng Wang ◽

Bao-Zhu Wang

Keyword(s):

Shell Thickness ◽

Light Trapping ◽

Mie Scattering ◽

Shell Structures ◽

Localized Surface Plasmon ◽

Core Shell ◽

Ag Nps ◽

Shell Nanoparticles ◽

Plasmon Resonance Peak ◽

Scattering Efficiency

In this paper, the localized surface plasmon properties of Ag NPs and Ag / Al 2 O 3 core-shell NPs with core radii ranging from 20–120 nm were analyzed by Mie scattering theory. Using numerical simulations, we show that an increasing shell thickness for core-shell NPs results in a red-shifted plasmon resonance peak compared to Ag core NPs. An averaged scattering efficiency under AM1.5 illumination is used to characterize the scattering abilities of different NPs. For Ag / Al 2 O 3 core-shell structures, the averaged scattering efficiency increases and subsequently decreases with increasing shell thickness due to the competing influences of plasmon hybridization and phase delay. For larger radii NPs, such as R > 100 nm, the scattering abilities of core-shell structures are superior to those of spherical Ag NPs.

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Ag@TiO2 nanogranular films by gas phase synthesis as hybrid SERS platforms

Physical Chemistry Chemical Physics ◽

10.1039/c9cp03998h ◽

2019 ◽

Vol 21 (45) ◽

pp. 25090-25097 ◽

Cited By ~ 2

Author(s):

Nicolò Bontempi ◽

Emanuele Cavaliere ◽

Valentina Cappello ◽

Pasqualantonio Pingue ◽

Luca Gavioli

Keyword(s):

Gas Phase ◽

Inner Core ◽

Core Shell ◽

Shell Nanoparticles ◽

Cluster Technique ◽

Phase Synthesis ◽

Dielectric Substrates ◽

Dielectric Shell ◽

Core Shell Nanoparticles ◽

Beam Deposition

The synthesis of hybrid metallic-dielectric substrates as reliable SERS platforms relies on core–shell nanoparticles, obtained by supersonic beam deposition cluster technique, with an outer dielectric shell composed of TiO2 and an inner core of Ag.

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Design of Bistable Gold@Spin-Crossover Core-Shell Nanoparticles Showing Large Electrical Responses for the Spin Switching

10.26434/chemrxiv.7543121.v1 ◽

2019 ◽

Author(s):

Ramón Torres-Cavanillas ◽

Rocher Sanchis-Gual ◽

Julien Dugay ◽

Marc Coronado-Puchau ◽

Dr. Mónica Giménez Marqués ◽

...

Keyword(s):

Spin Crossover ◽

Thermal Hysteresis ◽

Spin Transition ◽

Hysteresis Loops ◽

Large Change ◽

Core Shell ◽

Shell Nanoparticles ◽

Simple Protocol ◽

Order Of Magnitude ◽

Core Shell Nanoparticles

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Wavelength-specific forward scattering of light by Bragg-reflective iridocytes in giant clams

Journal of The Royal Society Interface ◽

10.1098/rsif.2016.0285 ◽

2016 ◽

Vol 13 (120) ◽

pp. 20160285 ◽

Cited By ~ 9

Author(s):

Amitabh Ghoshal ◽

Elizabeth Eck ◽

Michael Gordon ◽

Daniel E. Morse

Keyword(s):

Lamellar Spacing ◽

Forward Direction ◽

Mie Scattering ◽

Forward Scattering ◽

Giant Clam ◽

Optical Behaviour ◽

Back Reflection ◽

Electromagnetic Simulations ◽

Giant Clams ◽

Reflected Light

A surprising recent discovery revealed that the brightly reflective cells (‘iridocytes’) in the epithelia of giant clams actually send the majority of incident photons ‘forward’ into the tissue. While the intracellular Bragg reflectors in these cells are responsible for their colourful back reflection, Mie scattering produces the forward scattering, thus illuminating a dense population of endosymbiotic, photosynthetic microalgae. We now present a detailed micro-spectrophotometric characterization of the Bragg stacks in the iridocytes in live tissue to obtain the refractive index of the high-index layers (1.39 to 1.58, average 1.44 ± 0.04), the thicknesses of the high- and low-index layers (50–150 nm), and the numbers of pairs of layers (2–11) that participate in the observed spectral reflection. Based on these measurements, we performed electromagnetic simulations to better understand the optical behaviour of the iridocytes. The results open a deeper understanding of the optical behaviour of these cells, with the counterintuitive discovery that specific combinations of iridocyte diameter and Bragg-lamellar spacing can produce back reflection of the same colour that is also scattered forward, in preference to other wavelengths that are scattered at higher angles. We find for all values of size and wavelength investigated that more than 90% of the incident energy is carried by the photons that are scattered in the forward direction; while this forward scattering from each iridocyte shows very narrow angular dispersion ( ca ±6°), the multiplicative scattering from a layer of ca 20 iridocytes broadens this dispersion to a cone of approximately ±90°. This understanding of the complex biophotonic dynamics enhances our comprehension of the physiologically, ecologically and evolutionarily significant light environment inside the giant clam, which is diffuse and nearly white at small tissue depths and downwelling, relatively monochromatic, and can be the same colour as the back-reflected light at greater depths in the tissue. Originally thought to be unique, cells of similar structure and photonic activity are now recognized in other species, where they serve other functions. The behaviour of the iridocytes opens possible new considerations for conservation and management of the valuable giant clam resource and new avenues for biologically inspired photonic applications.

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