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1

Valagiannopoulos, Constantinos, S. Ali Hassani Gangaraj, and Francesco Monticone. "Zeeman gyrotropic scatterers." Nanomaterials and Nanotechnology 8 (January 1, 2018): 184798041880808. http://dx.doi.org/10.1177/1847980418808087.

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Anomalous scattering effects (invisibility, superscattering, Fano resonances, etc) enabled by complex media and metamaterials have been the subject of intense efforts in the past couple of decades. In this article, we present a full analysis of the unusual and extreme scattering properties of an important class of complex scatterers, namely, gyrotropic cylindrical bodies, including both homogeneous and core–shell configurations. Our study unveils a number of interesting effects, including Zeeman splitting of plasmonic scattering resonances, tunable gyrotropy-induced rotation of dipolar radiation patterns as well as extreme Fano resonances and non-radiating eigenmodes (embedded eigenstates) of the gyrotropic scatterer. We believe that these theoretical findings may enable new opportunities to control and tailor scattered fields beyond what is achievable with isotropic reciprocal objects, being of large significance for different applications, from tunable directive nano-antennas to selective chiral sensors and scattering switches, as well as in the context of nonreciprocal and topological metamaterials.
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2

Orzechowski, Kamil, Martyna Wasiluk, Konrad Jabłoński, et al. "Designated ligand functionalization of gold nanoparticles for optimizing blue-phase liquid crystal composites." Photonics Letters of Poland 16, no. 4 (2024): 71–75. https://doi.org/10.4302/plp.v16i4.1304.

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This work presents the impact of the composition of the organic shell of 4 nm gold nanoparticles (Au NPs) on the optical properties and stability of the nanoparticle-doped blue-phase liquid crystals (BPLCs). Particularly, we show that the binary shell of NPs, comprising LC-like ligands, can significantly enhance the thermal stability of BPs. Moreover, modifying the shell composition enables control over the Bragg wavelength of BPLCs. Our findings highlight the potential of ligand-functionalized Au NPs to optimize BPLC-based photonic devices, emphasizing ligand functionalization as a crucial factor for improving stability of NPs, and controlling BPLC properties. Full Text: PDF References S. Meiboom and M. Sammon, "Structure of the Blue Phase of a Cholesteric Liquid Crystal", Phys. Rev. Lett., 44(13), 882 (1980). CrossRef S. Tanaka et al. "Muographic mapping of the subsurface density structures in Miura, Boso and Izu peninsulas, Japan", Sci. Rep. 5(1), 16180 (2015). CrossRef W. Cao, A. Muñoz, P. Palffy-Muhoray, B. Taheri, "Lasing in a three-dimensional photonic crystal of the liquid crystal blue phase II", Nat. Mater. 1(2), 111 (2002). CrossRef H. Yoshida et al. "Heavy meson spectroscopy under strong magnetic field", Phys. Rev. E 94(4), 042703 (2016). CrossRef K. Orzechowski et al. "Polarization properties of cubic blue phases of a cholesteric liquid crystal", Opt. Mater. 69, 259 (2017). CrossRef H. Yoshida et al. "Nanoparticle-Stabilized Cholesteric Blue Phases", Appl. Phys. Express 2(12), 121501 (2009). CrossRef M. A. Gharbi et al. "Reversible Nanoparticle Cubic Lattices in Blue Phase Liquid Crystals", ACS Nano, 10(3), 3410 (2016). CrossRef W.-L. He et al. "Preparation and optical properties of Fe3O4 nanoparticles-doped blue phase liquid crystal", hys. Chem. Chem. Phys. 18(42), 29028 (2016). CrossRef A.P. Draude, T.Y. Kalavalapalli, M. Iliut, B. McConnell, and I. Dierking, "Stabilization of liquid crystal blue phases by carbon nanoparticles of varying dimensionality", Nanoscale Adv. 2(6), 2404 (2020). CrossRef M. Lavrič et al. "Blue phase stabilization by CoPt-decorated reduced-graphene oxide nanosheets dispersed in a chiral liquid crystal", J. Appl. Phys. 127(9), 095101 (2020). CrossRef M. Ravnik, G.P. Alexander, J.M. Yeomans, and S. Žumer, "Three-dimensional colloidal crystals in liquid crystalline blue phases", Proc. Natl. Acad. Sci. 108(13), 5188 (2011). CrossRef K. Orzechowski et al. "Achiral Nanoparticle-Enhanced Chiral Twist and Thermal Stability of Blue Phase Liquid Crystals", ACS Nano 16(12), 20577 (2022). CrossRef U.N. Tohgha, E.P. Crenshaw, M.E. McConney, K.M. Lee, N.P. Godman, "Tuning of optical properties and phase behavior of Nanomaterial-stabilized blue phase liquid crystals", J. Colloid Interface Sci. 639, 401 (2023). CrossRef O. Chojnowska, R. Dąbrowski, J. Yan, Y. Chen, S.T. Wu, "Electro-optical properties of photochemically stable polymer-stabilized blue-phase material", J. Appl. Phys. 116(21), 213505 (2014). CrossRef P. Kula, J. Herman, O. Chojnowska, "Synthesis and properties of terphenyl- and quaterphenyl-based chiral diesters", Liq. Cryst. 40(1), 83 (2013). CrossRef M. Brust, M. Walker, D. Bethell, D.J. Schiffrin, R. Whyman, "Synthesis of thiol-derivatised gold nanoparticles in a two-phase Liquid–Liquid system", J. Chem. Soc. Chem. Commun. 7, 801 (1994). CrossRef J. Grzelak, M. Żuk, M. Tupikowska, and W. Lewandowski, "Modifying Thermal Switchability of Liquid Crystalline Nanoparticles by Alkyl Ligands Variation", Nanomaterials 8(3), 147 (2018). CrossRef M. Bagiński et al. "Understanding and Controlling the Crystallization Process in Reconfigurable Plasmonic Superlattices", ACS Nano 15(3), 4916 (2021). CrossRef
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3

Wei Si-Yu, Huang Hao, Ma Xiao-Yun, Huang Hai-Wen, Xu Xin, and Wang Rong-Yao. "Selective modulation of the plasmonic circular dichroism enabled by synergic asymmetric optomechanical and photothermal effects in nano-plasmonic chiral structures." Acta Physica Sinica 74, no. 14 (2025): 0. https://doi.org/10.7498/aps.74.20250423.

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Nano-plasmonic chiral structures exhibit stronger plasmonic circular dichroism than most organic materials. In addition to the circular dichroism response, the interaction between light and nano-plasmonic chiral structures also involves the photothermal and optomechanical effects. However, the synergistic effect between the photothermal and optomechanical effects under circularly polarized light excitation remains poorly understood. This article investigates the synergistic effect of the photothermal and optomechanical effects in chiral gold nanorod trimers. The asymmetric photothermal and optomechanical effects in gold nanorod trimers with adjacent homochiral centers are analyzed by finite element simulation. The simulation results show that the dynamic structure of the chiral gold nanorod trimers is activated when the photothermal temperature reaches the threshold value. At the same time, the asymmetric optical torque generated by left- and right-handed circularly polarized light will lead to asymmetric changes in the geometry of the gold nanorod trimer, especially in the twist angle of the chiral center, so that the spectral response of the gold nanorod trimer is polarization-dependent. More significantly, based on the synergistic effect of the photothermal and optomechanical effects, experimental results show that the chiral gold nanorod oligomers can be used to control the asymmetric enhancement and suppression of the plasmonic circular dichroic spectral response through the enantioselective interaction of left- and right-handed circularly polarized light. This study provides an important reference for the design of advanced nano-photonics devices.
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4

Zakomirnyi, Vadim I., Ilia L. Rasskazov, Lasse K. Sørensen, P. Scott Carney, Zilvinas Rinkevicius, and Hans Ågren. "Plasmonic nano-shells: atomistic discrete interaction versus classic electrodynamics models." Physical Chemistry Chemical Physics 22, no. 24 (2020): 13467–73. http://dx.doi.org/10.1039/d0cp02248a.

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Using the extended discrete interaction model and Mie theory, we investigate the tunability of the optical polarizability and show the size-dependence of the plasma frequency of small metallic nano-shells in the 1–15 nm size region.
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5

Csernai, L. P., N. Kroo, and I. Papp. "Radiation dominated implosion with nano-plasmonics." Laser and Particle Beams 36, no. 2 (2018): 171–78. http://dx.doi.org/10.1017/s0263034618000149.

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AbstractInertial Confinement Fusion is a promising option to provide massive, clean, and affordable energy for mankind in the future. The present status of research and development is hindered by hydrodynamical instabilities occurring at the intense compression of the target fuel by energetic laser beams. A recent patent combines advances in two fields: Detonations in relativistic fluid dynamics (RFD) and radiative energy deposition by plasmonic nano-shells. The initial compression of the target pellet can be decreased, not to reach the Rayleigh–Taylor or other instabilities, and rapid volume ignition can be achieved by a final and more energetic laser pulse, which can be as short as the penetration time of the light across the pellet. The reflectivity of the target can be made negligible as in the present direct drive and indirect drive experiments, and the absorptivity can be increased by one or two orders of magnitude by plasmonic nano-shells embedded in the target fuel. Thus, higher ignition temperature and radiation dominated dynamics can be achieved with the limited initial compression. Here, we propose that a short final light pulse can heat the target so that most of the interior will reach the ignition temperature simultaneously based on the results of RFD. This makes the development of any kind of instability impossible, which would prevent complete ignition of the target.
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6

Tatsuma, Tetsu, and Takuya Ishida. "(Invited) Plasmonic Fabrication of Chiral and Magneto-Chiral Nanostructures." ECS Meeting Abstracts MA2024-02, no. 59 (2024): 3970. https://doi.org/10.1149/ma2024-02593970mtgabs.

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Chiral and magneto-chiral plasmonic nanostructures attract attention because they have various potential applications including catalysts, chemical sensors, and optical and optoelectronic materials and devices. In many cases, those nanostructures are fabricated by lithographic techniques. However, those top down methods are generally time-consuming and expensive. Therefore, we have developed photoelectrochemical methods in which site-selective deposition or dissolution reactions are driven by optical near field generated around anisotropic metal nanoparticles under right- or left-circularly polarized light (CPL). We have used gold or silver nanocuboids,1 nanorods,2 nanocubes,3 triangular nanoplates,4 and intricate nanoporous films5 on semiconducting or dielectric substrates as anisotropic metal precursors for preparation of chiral plasmonic nanostructures. If an anisotropic metal nanoparticle is irradiated with CPL, chiral electric field is generated around the nanoparticle, and energetic electron-hole pairs generate at the resonance sites, where electric field is localized. As a result, reductive deposition of silver or oxidative deposition of lead oxide proceeds preferentially at the resonance sites, resulting in formation of chiral plasmonic nanostructures, which exhibit circular dichroism (CD). Chiral metal nanoparticles were also prepared from less anisotropic, circular metal nanodisks. In this case, initial nucleation of metal at an arbitrary site of the nanodisk edge breaks its symmetry and gives rise to chiral electric field distributions under CPL. As a result, the nanodisk is grown into chiral plasmonic nanostructure. We also prepared magneto-chiral nanostructures by employing superparamagnetic magnetite nanocubes as precursors. The magnetite nanocubes on a glass substrate exhibit magnetic circular dichroism (MCD) but not CD. Magnetite is also reported to be conducting enough for its nanoparticles to show LSPR. Therefore, chiral electric field generates at around a magnetite nanocube under CPL and plasmonic photoelectrochemical reactions can proceed at those localized resonance sites. In addition, magnetite also has valence band and conduction band, and an electron in the valence band can be excited to the conduction band by a photon with energy higher than the band-gap energy. This photoexcitation can also occur at the localized resonance sites.6 As a result of those localized photoelectrochemical reactions induced by CPL, chiral magnetite-silver nanocomposite structures were obtained, and those nanocomposites not only MCD but also CD based on the chiral morphologies. Thus, the nanocomposites break both inversion and time-reversal symmetries. As a result, they exhibit nonreciprocal transmission of visible light, which is recognized also as magneto-chiral dichroism (MChD). K. Saito and T. Tatsuma, Nano Lett. 18, 3209-3212 (2018). K. Morisawa, T. Ishida, and T. Tatsuma, ACS Nano 14, 3603-3609 (2020). K. Shimomura, Y. Nakane, T. Ishida, and T. Tatsuma, Appl. Phys. Lett. 122, 151109 (2023). T. Ishida, A. Isawa, S. Kuroki, Y. Kameoka, and T. Tatsuma, Appl. Phys. Lett. 123, 061111 (2023). H. Nishi, T. Tojo, and T. Tatsuma, Electrochemistry in press (doi: 10.5796/electrochemistry.24-00027). Y. Oba, S. H. Lee, and T. Tatsuma, J. Phys. Chem. C 128, 827-831 (2024). Figure 1
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7

Amboli, Jayeeta, Guillaume Demésy, Bruno Galas, and Nicolas Bonod. "Numerical investigation of far-field circular dichroism and local chiral response of pseudo-chiral meta-surface with FEM." EPJ Web of Conferences 266 (2022): 05001. http://dx.doi.org/10.1051/epjconf/202226605001.

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Circular dichroism spectroscopy is a sensitive and widely applied technique to detect chiral molecules. Recent studies have shown high prospects for plasmonic metasurfaces of pseudo-chiral nano-resonators in enhancing chiral sensitivity. Here we study the far-field circular dichroism for gold U-shaped metasurfaces by calculating Mueller matrix elements with the Finite element method and investigate its response in light of the near field electric energy and optical chiral density.
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8

Tatsuma, Tetsu, Takuya Ishida, and Yuri Kameoka. "(Invited) Plasmonic Nanofabrication of Chiral Nanodisk Ensembles." ECS Meeting Abstracts MA2024-01, no. 13 (2024): 1099. http://dx.doi.org/10.1149/ma2024-01131099mtgabs.

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Chiral plasmonic nanostructures attract attention because those could be applied to enantioselective chemical sensors, optical isolators, light sources for circularly polarized light (CPL), metasurfaces, and metamaterials. In many cases, chiral plasmonic nanostructures are fabricated by a top-down method such as electron beam lithography (EBL). Since EBL is time-consuming and expensive, we have developed photoelectrochemical methods in which a site-selective reaction is driven by optical near field generated around anisotropic metal nanoparticles under right- or left-CPL. As anisotropic metal precursors for preparation of chiral nanoparticles, we have used gold or silver nanocuboids, nanorods, nanocubes, and triangular or hexagonal nanoplates so far.1-5 In the present work we demonstrate that laterally isotopic, circular nanodisks can also be used as precursors for the preparation of chiral nanostructures. We prepared ensembles of circular gold nanodisks on a glass plate by a nanosphere lithography method. A glass plate was coated with a gold thin film, and an array of polystyrene spheres (500 nm diameter) was prepared on the gold film. The polystyrene spheres were etched by oxygen plasma, and the exposed gold film was etched by argon ion milling. As a result, an ensemble of gold nanodisks (~200 nm diameter) was obtained. Each nanodisk was capped with a polystyrene cone, and the cap was removed by sonication in toluene if necessary. We used both capped and uncapped nanodisk ensembles. The ensemble was irradiated with visible right- or left-CPL in the presence of silver ions and sodium citrate. The obtained Au-Ag nanostructures exhibited circular dichroism (CPL), indicating that the nanostructures have chirality. Initial deposition at arbitrary site may break the geometric symmetry, resulting in the growth into chiral structures. Saito, K.; Tatsuma, T. Nano Lett. 2018, 18, 3209–3212. Morisawa, K.; Ishida, T.; Tatsuma, T. ACS Nano 2020, 14, 3603–3609. Shimomura, K.; Nakane, Y.; Ishida, T.; Tatsuma, T. Appl. Phys. Lett. 2023, 122, 151109. Homma, T.; Sawada, N.; Ishida, T.; Tatsuma, T. ChemNanoMat 2023, 9, e202300096. Ishida, T.; Isawa, A.; Kuroki, S.; Kameoka, Y.; Tatsuma, T. Appl. Phys. Lett. 2023, 123, 061111.
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9

Yadav, Vikas, and Soumik Siddhanta. "Engineering chiral plasmonic nanostructures for gain-assisted plasmon amplification and tunable enhancement of circular dichroism." Materials Advances 3, no. 3 (2022): 1825–33. http://dx.doi.org/10.1039/d1ma01067k.

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We have demonstrated that the SPASER configuration can provide giant chiroptical enhancements in plasmonic nano assemblies within the lasing threshold which can be harnessed for highly efficient chiral sensing or imaging of complex biological environments.
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10

Klös, Gunnar, Amanda Andersen, Matteo Miola, Henrik Birkedal, and Duncan S. Sutherland. "Oxidation controlled lift-off of 3D chiral plasmonic Au nano-hooks." Nano Research 12, no. 7 (2019): 1635–42. http://dx.doi.org/10.1007/s12274-019-2412-x.

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11

Tatsuma, Tetsu, Takuya Ishida, and Hiroyasu Nishi. "(Invited) Photoelectrochemical Fabrication of Chiral Plasmonic Nanostructures By Circularly Polarized Light." ECS Meeting Abstracts MA2022-01, no. 13 (2022): 929. http://dx.doi.org/10.1149/ma2022-0113929mtgabs.

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Chiral plasmonic nanostructures attracts attention because they are potentially applicable to optical materials such as enantioselective sensors and metamaterials, as well as photoelectrochemical devices. Chiral nanostructures are often prepared by electron beam lithography or synthesis based on DNA templates. We have recently developed a photoelectrochemical method, in which handedness of the chiral nanostructure can be controlled by right- or left- circularly polarized light. The photoelectrochemical method is based on plasmon-induced charge separation (PICS),1,2 in which electrons are injected from a plasmonic metal nanoparticle to a semiconductor such as titania in direct contact. In PICS, anodic reactions often occur at the resonance sites of the plasmonic nanoparticle, at which electron oscillation is localized.3,4 Energetic electron-hole pairs generate at the resonance site, and holes are used for the local anodic reaction, probably via trap sites. On the basis of the mechanisms, we have demonstrated site-selective etching of silver nanoparticles and site-selective deposition of lead oxide on gold nanoparticles. Under right-circularly polarized light (CPL), distribution of the resonance sites could be the mirror image of that under left-CPL.5 Therefore, we performed site-selective deposition of lead oxide on gold nanocuboids on titania under right- or left-CPL.6 As a result, lead oxide was deposited on the gold nanocuboids in a chiral geometry. The nanostructures thus obtained exhibited circular dichroism (CD), and the CD spectrum obtained for the structure prepared under right-CPL was opposite to that obtained for the structure prepared under left-CPL. Reversible switching of the handedness of the chiral plasmonic nanostructures can also be possible.7 This method also allows us to fabricate spiral nanostructures. 1. Y. Tian and T. Tatsuma, J. Am. Chem. Soc., 127, 7632 (2005). 2. T. Tatsuma, H. Nishi, and T. Ishida, Chem. Sci., 8, 3325 (2017) [review]. 3. I. Tanabe and T. Tatsuma, Nano Lett., 12, 5418 (2012). 4. T. Tatsuma and H. Nishi, Nanoscale Horiz., 5, 597 (2020) [review]. 5. S. Hashiyada, T. Narushima, and H. Okamoto, J. Phys. Chem. C, 118, 22229 (2014). 6. K. Saito and T. Tatsuma, Nano Lett., 18, 3209 (2018). 7. K. Morisawa, T. Ishida, and T. Tatsuma, ACS Nano, 14, 3603 (2020).
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12

Zhao, Jun, Bettina Frank, Frank Neubrech, Chunjie Zhang, Paul V. Braun, and Harald Giessen. "Hole-mask colloidal nanolithography combined with tilted-angle-rotation evaporation: A versatile method for fabrication of low-cost and large-area complex plasmonic nanostructures and metamaterials." Beilstein Journal of Nanotechnology 5 (May 6, 2014): 577–86. http://dx.doi.org/10.3762/bjnano.5.68.

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Many nano-optical applications require a suitable nanofabrication technology. Hole-mask colloidal nanolithography has proven to be a low-cost and large-area alternative for the fabrication of complex plasmonic nanostructures as well as metamaterials. In this paper, we describe the fabrication process step by step. We manufacture a variety of different plasmonic structures ranging from simple nano-antennas over complex chiral structures to stacked composite materials for applications such as sensing. Additionally, we give details on the control of the nanostructure lateral density which allows for the multilayer-fabrication of complex nanostructures. In two accompanying movies, the fabrication strategy is explained and details are being demonstrated in the lab. The movies can be found at the website of Beilstein TV.
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13

Chen, Shanshan, Chang-Yin Ji, Yu Han, et al. "Plasmonic diastereoisomer arrays with reversed circular dichroism simply controlled by deformation height." APL Photonics 7, no. 5 (2022): 056102. http://dx.doi.org/10.1063/5.0085981.

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Chirality reversal between enantiomers is of great importance in both fundamental science and practical applications in chiroptics, biomedicine, and analytical chemistry. Here, we demonstrate an abrupt sign reversal of circular dichroism (CD) between artificial plasmonic diastereoisomers, which are a kind of stereo twisted metamolecules with different strength of deformations. The sign of the CD response is reversed in the same wavelength region by simply engineering the deformation height of nanostructures. Electromagnetic multipolar analysis shows that the sign of CD is determined by the phase-controlled handedness-dependent excitations of electric quadrupole modes. The numerical simulations are further verified by experiments using a nano-kirigami fabrication method. This work reveals that under certain circumstances, the CD response of the plasmonic diastereoisomers can be very close to that of enantiomers, which is useful for the exploration of profound chiroptics, as well as for the applications in chirality switching, chiral biosensing, and chiral separation.
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14

Roychoudhury, Piya, Rahul Bose, Przemysław Dąbek, and Andrzej Witkowski. "Photonic Nano-/Microstructured Diatom Based Biosilica in Metal Modification and Removal—A Review." Materials 15, no. 19 (2022): 6597. http://dx.doi.org/10.3390/ma15196597.

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The siliceous exoskeletal shells of diatoms, commonly known as frustules, have drawn attention because of their photoluminescence property and high volume to surface area. Photonic biosilica can also enhance the plasmonic sensitivity of nanoparticles. Because of this, researchers have studied the effectiveness of various metal particles after combining with biosilica. Additionally, naturally occurring diatom-based biosilica has excellent adsorption and absorption capabilities, which have already been exploited for wastewater treatment. Moreover, the nanoporous, ultra-hydrophilic frustules can easily accumulate more molecules on their surfaces. As a consequence, it becomes easier to conjugate noble metals with silica, making them more stable and effective. The main focus of this review is to agglomerate the utility of biocompatible diatom frustules, which is a no-cost natural resource of biosilica, in metal modification and removal.
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15

Ghimire, Rupesh, Jhih-Sheng Wu, Vadym Apalkov, and Mark I. Stockman. "Topological nanospaser." Nanophotonics 9, no. 4 (2020): 865–74. http://dx.doi.org/10.1515/nanoph-2019-0496.

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AbstractWe propose a nanospaser made of an achiral plasmonic–metal nanodisk and a two-dimensional chiral gain medium – a monolayer nanoflake of a transition-metal dichalcogenide (TMDC). When one valley of the TMDC is selectively pumped (e.g. by a circular-polarized radiation), the spaser (surface plasmon amplification by stimulated emission of radiation) generates a mode carrying a topological chiral charge that matches that of the gain valley. There is another, chirally mismatched, time-reversed mode with exactly the same frequency but the opposite topological charge; it is actively suppressed by the gain saturation and never generates, leading to a strong topological protection for the generating matched mode. This topological spaser is promising for use in nano-optics and nanospectroscopy in the near field especially in applications to biomolecules that are typically chiral. Another potential application is a chiral nanolabel for biomedical applications emitting in the far field an intense circularly polarized coherent radiation.
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Osanloo, Nahid, Vahid Ahmadi, Mohammad Naser-Moghaddasi, and Elham Darabi. "Engineered nano-sphere array of gold-DNA core–shells and junctions as opto-plasmonic sensors for biodetection." RSC Advances 11, no. 44 (2021): 27215–25. http://dx.doi.org/10.1039/d1ra03079e.

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17

Csernai, L. P. "Advances in Relativistic Fluid Dynamics, Observables, and Applications - In Memoriam Walter Greiner." EPJ Web of Conferences 182 (2018): 01002. http://dx.doi.org/10.1051/epjconf/201818201002.

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Walter Greiner was one of the first physicists using Relativistic Fluid Dynamics for High Energy Nuclear Reactions. The present Inertial Confinement Fusion research and development is hindered by hydrodynamic instabilities, occurring at the intense compression of the target fuel by energetic laser beams. The suggested method combines recent advances in two fields: detonations in relativistic fluid dynamics and radiative energy deposition by plasmonic nano-shells. The compression of the target can be negligible and a laser pulse achieves rapid volume ignition, which is as short as the penetration time of the light across the pellet. The reflectivity of the target can be made negligible, and the absorptivity can be increased by one or two orders of magnitude using plasmonic nanoshells embedded in the target fuel. Thus, higher ignition temperature can be achieved with modest compression. The short light pulse can heat most of the interior of the target to the ignition temperature simultaneously. This prevents the development of any kind of instability, which would prevent complete ignition or transition of the target.
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18

Tatsuma, Tetsu, Seung Hyuk Lee, Yuki Oba, and Genki Horiuchi. "(Invited) Near Field Photocatalysis for Site-Selective Reactions By Using ZnO Nanoplates." ECS Meeting Abstracts MA2024-01, no. 35 (2024): 1963. http://dx.doi.org/10.1149/ma2024-01351963mtgabs.

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Nanofabrication is a technology for control of the morphology, orientation, and configuration of nanomaterials. When ordinary, propagating light is employed as a processing tool, subwavelength fabrication is difficult due to the diffraction limit. However, if optical near field, which is localized in a subwavelength region is used, nanofabrication beyond the diffraction limit is possible. We have demonstrated that subwavelength nanofabrication is possible by taking advantage of the optical near field. Since hot electron-hole pairs are generated at around the plasmonic resonance sites, the energetic carriers can be used to drive oxidative dissolution of Ag,1,2 oxidative deposition of PbO2,3,4 and reductive deposition of Ag,5 in a site-selective manner. These techniques have been applied to subwavelength photochromic data storage,1,2 fabrication of chiral nanoparticles,4-7 and site-selective modification of a plasmonic photocatalyst with a co-catalyst.8 Generation of optical near field is possible even at non-plasmonic, semiconducting or dielectric nanostructures. Here we employed In-doped ZnO (In:ZnO) as a semiconductor photocatalyst. Hexagonal In:ZnO nanoplates were synthesized and adsorbed onto a glass substrate, and irradiated with linearly polarized UV light in the presence of Ag ions for reductive deposition of Ag. The optical near field generated under polarized UV light gave rise to site-selective Ag deposition. Also, the sample exhibited linear dichroism (LD) signals, indicating that the nanoparticles have optical anisotropy. On the other hand, unpolarized UV light gave no optical anisotropy. Electromagnetic simulations successfully reproduced the LD spectra. We have also performed site-selective oxidation reactions by using the hexagonal In:ZnO nanoplates. Tanabe, I.; Tatsuma, T. Nano Lett. 2012, 12, 5418–5421. Saito, K.; Tanabe, I.; Tatsuma, T. J. Phys. Chem. Lett. 2016, 7, 4363–4368. Nishi, H.; Sakamoto, M.; Tatsuma, T. Chem. Commun. 2018, 54, 11741–11744. Saito, K.; Tatsuma, T. Nano Lett. 2018, 18, 3209–3212. Ishida, T.; Isawa, A.; Kuroki, S.; Kameoka, Y.; Tatsuma, T. Appl. Phys. Lett. 2023, 123, 061111. Morisawa, K.; Ishida, T.; Tatsuma, T. ACS Nano 2020, 14, 3603–3609. Shimomura, K.; Nakane, Y.; Ishida, T.; Tatsuma, T. Appl. Phys. Lett. 2023, 122, 151109. Kim, K.; Nishi, H.; Tatsuma, T. J. Chem. Phys. 2022, 157, 111101.
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Krishana, Shivam, and Nabin Kumar. "Asymmetric Transmission in Diffractive Chiral Metasurfaces Consisting of Nanoantennas." Bulletin of Pure and Applied Sciences – Physics 42, no. 2 (2023): 89–92. http://dx.doi.org/10.48165/bpas.2023.42d.2.5.

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We have studied the asymmetric transmission in diffractive chiral metasurfaces consisting of nanoantennas. The study was made of lattice plasmon modes on the phenomenon of asymmetric transmission in chiral two dimensional arrays of plasmonic nanoparticles. It was demonstrated that asymmetric transmission resulted from contribution of higher order diffracted waves. It was shown that the isolated nanostructures has a fourfold rotational symmetry, the diffractive metasurfaces exhibited asymmetric transmission for normal incidence light within spectral range for which lattice plasmon modes were supported. It was found that lattice plasmon modes played role in enabling symmetric transmission in diffractive chiral metasurfaces. The symmetric transmission mechanism is due to different lattice plasmon mode excitation efficiencies of left circularly polarized and right circularly polarized and right circularly polarized light. The excitation efficiencies are controlled by tailoring the nano particles in plan distribution of scattered light for circularly polarized excitation and its alignment with the inplane diffraction orders of the metasurfaces. The phenomenon for a metasurface composed of an array of a chiral nanoparticles consisting of four nanoantennas. It was shown that the Rayleigh anomaly condition where the asymmetric transmission effect was strongest and metasurfaces supported lattice plasmon modes. It was found that the difference in the inplane scattered intensity varied as a function of the inplane angle around the nanostructure, rotating the nanostructure in the plane of the metasurface. The obtained results found in good agreement with previously obtained results.
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20

Biswas, Sudipta, M. R. C. Mahdy, Saikat Chandra Das, Md Ariful Islam Bhuiyan, and Mohammad Abir Talukder. "Controlling the counterintuitive optical repulsive thrust of nano dimers with counter propagating type waves and background medium." PLOS ONE 18, no. 12 (2023): e0295679. http://dx.doi.org/10.1371/journal.pone.0295679.

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This work focuses on the utilization of counter-propagating plane waves for optical manipulation, which provides a unique approach to control the behavior of Rayleigh and Dipolar nanoparticles immersed in a homogeneous or heterogeneous medium. Our study presents an interesting finding of a repulsive force between plasmonic-chiral heterodimers where the particles move away from each other in both near and far field regions. Interestingly, this repulsive thrust supports the wave like nature of light for the case of homogeneous background but particle type nature of light for heterogenous background. At first, we have investigated the theory underlying the optical trapping of the chiral particle and the impact of this phenomenon on the overall repulsive behavior of the heterodimers placed in air (homogeneous) background. After that, our proposed set-up has further been investigated putting in air-water interface (heterogenous background) and by varying light angle only a little bit. Our observation for this interface case is suggesting the transfer of Minkowski momentum of photon to each optically pulled Rayleigh or dipolar particle of the dimer set, which ultimately causes a broad-band giant repulsive thrust of the dimers. However, in absence of the other particle in the cluster, a single half-immersed particle does not experience the pulling force for the broad-band spectrum. The ‘common’ reason of the observed repulsive thrust of the dimers for both the aforementioned cases has been attributed to "modified" longitudinal Optical Binding Force (OBF). Technically, this work may open a new way to control the repulsion and attraction between the nanoparticles both in near and far field regions by utilizing the background and the counter-propagating waves. We also believe that this work manifests a possible simple set-up, which will support to observe a background dependent wave ‘or’ particle nature of light experimentally.
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21

Thomas, K. George. "(Invited) Emergent Chiroptical Properties in Assembled Molecules and Materials: From Native Chirality to Global Chirality." ECS Meeting Abstracts MA2024-01, no. 10 (2024): 940. http://dx.doi.org/10.1149/ma2024-0110940mtgabs.

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The emergence of chiroptical properties in molecules and materials through their asymmetric organizations has fascinated humankind in general and the scientific community in particular. By adopting molecules, plasmonic systems, and semiconductor quantum dots as examples, the translation of ‘local’ chirality in these building blocks to the ‘global’ chirality when they self-assemble as nanoobjects will be explained. The presentation covers the following aspects. In assembled molecular systems, induced circular dichroism (ICD) originates through the off-resonance coupling of transition dipoles, resulting in monosignated CD signals. In contrast, exciton-coupled circular dichroism (EC-CD) originates through the on-resonance exciton coupling, displaying bisignated CD signals.1-3 Bisignation in the CD responses of assembled plasmonic systems results from the resonant plasmon coupling, termed surface plasmon-coupled circular dichroism (SP-CD).4,5 The presentation will draw parallels between the emergence of EC-CD and SP-CD based on the coupling of their transition dipoles.3 More importantly, our studies have concluded that the sign of the EC-CD/SP-CD depends not only on the handedness of the assembly but also on the sign of the interaction energy between the neighboring dipoles.6 The presentation will also discuss how chiral surface domains of various self-assembled amino acid-based templates transfer chiral information to bound achiral chromophores. The origin of CD and CPL of achiral molecules on these templates are explained based on exciton coupling.7 The presentation will also provide fundamental insight into the interaction of chiral molecules with silicon nanoparticles and the emergence of its CD and CPL.8 An open challenge is to develop a universal model which can explain the chiroptical properties of assembled systems based on the transition dipolar coupling and interaction energy: our findings in this direction will be presented. Thomas R, Kumar J, George J, et al. Phys. Chem. Lett., 2018, 9, 919-932. Kar S, Swathi K, Sissa C, et al., Phys. Chem. Lett., 2018, 9, 4584-4590. Nizar NSS, Sujith M, Swathi K, et al. Soc. Rev.,2021, 50 , 11208-11226. George J, Thomas KG, J. Am. Chem. Soc. 2010, 132, 2502-2503. George J, Kar S, Anupriya ES, et al. ACS Nano 13, 2019, 4392-4401. Swathi K, Sissa C, Painelli A, et al. Commun. , 2020 , 56, 8281-8284. Somasundaran SM, Kompella SVK, Mohan TMN, et al. ACS Nano 2023 17, 11054-11069. Sujith M, Vishnu EK, Sappati S, et al. J. Am. Chem. Soc. , 2022, 144, 5074-5086. The theoretical collaborations with Dr. R. S. Swathi, IISER Thiruvananthapuram (India), Dr. Cristina Sissa and Prof. Anna Painelli, University of Parma (Italy), and Prof. S. Balasubramanian, JNCASR, Bangalore are greatly acknowledged. KGT acknowledges the J. C. Bose National Fellowship and Nanomission project (DST/NM/TUE/EE-01/2019), the Department of Science and Technology, Government of India, for financial support.
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22

Romero, Marcelo R., Alicia V. Veglia, Maria Valeria Amé, and Angel Guillermo Bracamonte. "Multimodal Spectroscopy Assays for Advanced Nano-Optics Approaches by Tuning Nano-Tool Surface Chemistry and Metal-Enhanced Fluorescence." Crystals 14, no. 4 (2024): 338. http://dx.doi.org/10.3390/cryst14040338.

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In this research work, different chemical modifications were applied to gold nanoparticles and their use in enhanced non-classical light emitters based on metal-enhanced fluorescence (MEF) was evaluated. In order to achieve this, gold core–shell nanoparticles with silica shells were modified via multilayered addition and the incorporation of a covalently linked laser dye to develop MEF. Their inter-nanoparticle interactions were evaluated by using additional silica shell multilayers and modified cyclodextrin macrocycles. In this manner, the sizes and chemical surface interactions on the multilayered nanoarchitectures were varied. These optical active nanoplatforms led to the development of different nanoassembly sizes and luminescence behaviors. Therefore, the interactions and nanoassembly properties were evaluated by using various spectroscopic and nanoimaging techniques. Highly dispersible gold core–shell nanoparticles with diameters of 50–60 nm showed improved colloidal dispersion that led to single ultraluminescent gold core–shell nanoparticles with MEF. Then, the addition of variable silica lengths produced increased interactions and consequent nanoaggregation. However, the silanized nanoparticles were easily dispersible after agitation or sonication. Thus, their sizes were proportional only to the diameter and the van de Waals interaction did not affect their sizes in bulk. Then, the covalent linking of different concentrations of modified cyclodextrins was applied to the chemical surfaces by incorporating additional hydroxyl groups from the glucose monomeric unities of cyclodextrins. In this manner, variable larger-sized and inter-branched grafted gold core–shell silica nanoparticles were generated. The ultraluminescent properties were conserved due to the non-optical activity of the cyclodextrins. However, they generated enhanced ultraluminescence phenomena. Laser fluorescence microscopy nanoimaging showed enhanced resolutions in comparison to non-grafted supramolecular gold core–shell nanoparticles. The differences in their interactions and the sizes of the nanoassemblies were explained by their single nanoparticle diameters and the interacting chemical groups on their nanosurfaces. While the varied luminescence emissions generated were tuned by plasmonics, enhanced plasmonic phenomena and light scattering properties were seen depending on the type of nanoassembly. Thus, optically active and non-optically active materials led to different optical properties in the bright field and enhanced the excited state within the electromagnetic near-field of the gold nanotemplates. In this manner, it was possible to achieve high sensitivity by varying the spacer lengths and optical properties. Therefore, further perspectives regarding the design of nano-tools composed of light for various applications were discussed.
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Frosch, Timea, Andreas Knebl, and Torsten Frosch. "Recent advances in nano-photonic techniques for pharmaceutical drug monitoring with emphasis on Raman spectroscopy." Nanophotonics 9, no. 1 (2019): 19–37. http://dx.doi.org/10.1515/nanoph-2019-0401.

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AbstractInnovations in Raman spectroscopic techniques provide a potential solution to current problems in pharmaceutical drug monitoring. This review aims to summarize the recent advances in the field. The developments of novel plasmonic nanoparticles continuously push the limits of Raman spectroscopic detection. In surface-enhanced Raman spectroscopy (SERS), these particles are used for the strong local enhancement of Raman signals from pharmaceutical drugs. SERS is increasingly applied for forensic trace detection and for therapeutic drug monitoring. In combination with spatially offset Raman spectroscopy, further application fields could be addressed, e.g. in situ pharmaceutical quality testing through the packaging. Raman optical activity, which enables the thorough analysis of specific chiral properties of drugs, can also be combined with SERS for signal enhancement. Besides SERS, micro- and nano-structured optical hollow fibers enable a versatile approach for Raman signal enhancement of pharmaceuticals. Within the fiber, the volume of interaction between drug molecules and laser light is increased compared with conventional methods. Advances in fiber-enhanced Raman spectroscopy point at the high potential for continuous online drug monitoring in clinical therapeutic diagnosis. Furthermore, fiber-array based non-invasive Raman spectroscopic chemical imaging of tablets might find application in the detection of substandard and counterfeit drugs. The discussed techniques are promising and might soon find widespread application for the detection and monitoring of drugs in various fields.
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Li, Lianmeng, Xiangyu Zeng, Manna Gu, et al. "Plasmonic Metasurfaces for Superposition of Profile-Tunable Tightly Focused Vector Beams and Generation of the Structured Light." Photonics 10, no. 3 (2023): 317. http://dx.doi.org/10.3390/photonics10030317.

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Vector beams (VBs) and their superposition have found important applications in versatile fields such as optical communications, super-resolution microscopy and quantum information, and metasurfaces have enabled the miniaturization and integration of the optical systems manipulating the vector beams, providing potential applications to subwavelength regimes. In this work, we propose a metasurface to realize the superposition of profile-tunable tightly focused VBs, with the novel structured light fields generated. The metasurface is composed of two sets of orthogonal-nanoslit pairs arranged on the inner and outer rings. By realizing the chiral conversion of circularly polarized light with the slit-pairs which act as half-wave plates, and by creating helical phase profiles of optical vortices with the geometrical phase of rotational nano-slit pairs, two focused Bessel VBs are formed. By finely varying the diameters of two sets of rings, the doughnuts of the two Bessel VBs of different orders are tuned to be of the same size, and the superposition of the two VBs is realized. The theoretical analyses of the superimposed fields were presented, the FDTD simulations were performed to optimize the designed metasurfaces, and the experimental measurements were carried out to validate feasibility of the metasurface. The novel and interesting characteristics of the superposed fields different from those of the conventional VBs were demonstrated. This work will be of significance for classical and quantum applications of VBs in various fields.
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Lopez-Munoz, Gerardo, Dominik Grochala, Anna Paleczek, et al. "Lithography-Free Metaplasmonic Sensors Developed by TWD/GLAD Technique." ECS Meeting Abstracts MA2024-01, no. 49 (2024): 2705. http://dx.doi.org/10.1149/ma2024-01492705mtgabs.

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Nowadays, plasmonic sensors are the most widely used and commercialized label-free optical biosensors and have become a widespread tool for studying chemical/biochemical interactions. Label-free, real-time, and direct measurements are the major benefits of the plasmonic sensors, including high-throughput surface bio-functionalization strategies without amplification or pretreatment of the sample [1]. The working principle of plasmonic sensing has been extensively described and reviewed over the decades [2], however, the possibility to develop cheap, effective, and clinically-accepted biosensors has recently become available due to the development of nanotechnology. Briefly, these nanostructures can be localized or can be arranged on 2D arrays of plasmonic metasurfaces, and can be fabricated by single-layer metallic films and a combination of metallic and dielectric films. The most popular plasmonic metals are gold and silver due to their high conductivity and low dielectric losses. Generally, top-down nanofabrication methods based on laser/e-beam lithography have been used, including nanostencil lithography based on shadow-masked nano-pattering and nanoimprint lithography [3]. Although such technologies have a high potential to achieve scalable and cost-effective nanofabrication at the wafer scale, these processes maintain the following main challenge: a master nano-mold/pattern is required to transfer metasurfaces with an associated high cost. Therefore, other technologies are the subject of research that overcomes this limitation and still offer an outstanding quality of metallic films, such as TDW (thermal dewetting) and GLAD (glancing angle deposition) (Fig.1). These techniques do not require master nano-mold/patterns; consequently, they can achieve lithography-free large-scale plasmonic metasurfaces [4]. TDW and GLAD usually generate quasi-ordered plasmonic metasurfaces compared to conventional lithographic methods. In this paper, the experimental results of the optical sensing properties of the sensors developed by the utilization of the combination of these two technologies in a single system are presented. The TWD/GLAD magnetron sputtering system has been designed and manufactured based on the Kurt J. Lesker MAG-Torus magnetrons, supplied with DC/RF power sources and an ECR manipulator that enables deposition at various angles with maximal 20 rpm rotation speed and heating option up to 850oC. The system is controlled by the software that enables deposition of the samples with the same parameters which pave the way for fabrication of the sensors on the industrial scale. The optical-sensing system was built based on an ST-VIS-50 spectrometer (Ocean Optics) and Tungsten Halogen Source (360-2000 nm, 2800 K, Ocean Optics) and optical table from Thorlabs. The obtained reflectance measurement has shown that the utilization of the GLAD technique decreases the reflectance peak in comparison with samples deposited without GLAD (flat samples). At the same time, angles in the range of 82-86oC seem to be preferable for nanostructure fabrication. Additionally, the utilization of the TWD technique, i.e. deposition at lower temperatures in the range of 60-100oC (depending on the substrate) and then annealed at higher temperatures such as 250oC and 300oC in a vacuum and under argon flow in the deposition chamber led to increased normalized response. However, the experiments have shown that the optimal annealing time is between 30-45 min depending on the SPR multi-structure, for example for Ag (6nm), Ti (2nm), and Au (2nm) the 30min at 250oC seems to be the best set. For such compositions, the surface sensitivity (nm/nm) and bulk sensitivity (nm/RIU) are more or less the same - 0.9 and 300, respectively. The obtained results are very promising for developing cheap, rapid, and very effective biosensors for various applications. Therefore, the obtained results seem to be very interesting for the ECS conference audience, for example, the developed Ag/Ti/Au multi-structures can be applied in novel organ-on-a-chip platforms for LADMET (liberations, absorption, distribution, metabolism, excretion, and toxicology) analysis [5]. Fig. 1. Schematic diagram representation of lithography free methods for developing quasi-ordered metamaterials from left to right: Thermal dewetting and glancing angle deposition. The insert shows the chiral plasmonic nanospirals fabrication by glanced angle deposition [4]. References: [1] LC Oliveira et al., Springer, 2019. ISBN: 9783030174859 [2] VG Kravets et al., Chem. Rev. 2018, 118, 12, 5912–5951. doi.org/10.1021/acs.chemrev.8b00243 [3] M. Zandieh et al., Analytical Biochemistry. 2018, 548, 96-101. doi.org/10.1016/j.ab.2018.02.023 [4] GA López-Muñoz et al., Front. Sens. 2022, 3:945525. doi: 10.3389/fsens.2022.945525 [5] J. Ramon, A. Rydosz, Human Organs-on-a-chip, 2023. ISBN: 9780443153846 The work was financially supported by the National Science Centre, Poland Sonata-BIS project no 2022/46/E/ST7/00008. Figure 1
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Tatsuma, Tetsu. "(Invited) Plasmonic Photocatalysis and Near-Field Photocatalysis." ECS Meeting Abstracts MA2024-02, no. 68 (2024): 4810. https://doi.org/10.1149/ma2024-02684810mtgabs.

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It is well known that finding of Honda-Fujishima effect1 opened up the way to semiconductor photocatalysis. The semiconductor photocatalysts, typically TiO2, are often modified with noble metal nanoparticles such as platinum as co-catalysts, for improvement of the photocatalytic activity. We modified TiO2 photocatalysts with plasmonic silver2 or gold3 nanoparticles and found that plasmon-induced charge separation (PICS) occurs at the metal-TiO2 interface.3,4 If a metal nanoparticle such as silver or gold is irradiated with light of the resonant wavelength, energetic electrons and holes are generated in the course of relaxation of the photoexcited plasmons. The electron can be injected into the conduction band of the TiO2 in contact with the resonant metal nanoparticle, and PICS is achieved (Figure 1a).3,4 We have applied PICS to visible-light-driven and NIR-light-driven photovoltaics and optoelectronic devices,3,4 photocatalysts,3,4 plasmonic chemical sensors,4 multicolor photochromic materials,2,4 and photo-morphing gels.4 For PICS, we can employ not only silver and gold nanoparticles, but also other plasmonic metal nanoparticles such as copper and plasmonic and electroconducting compound nanoparticles such as ITO. We have developed photovoltaic devices responsive to NIR light by coupling TiO2 with plasmonic ITO nanoparticles.5 If the plasmonic nanoparticles are morphologically or optically anisotropic, plasmonic electron oscillation is localized at certain resonance sites. In other words, optical near field is confined at the resonance sites. We can take advantage of the localization for nanoscale photo-fabrication beyond the diffraction limit, on the basis of deposition and dissolution reactions.6 We have fabricated variety of nanostructures, for instance anisotropic composite nanostructures and chiral plasmonic nanostructures (Figure 1b).7 ,8 Optical near field is generated by various processes other than plasmon resonance, for instance Mie resonance. Mie resonance occurs not only at metal nanoparticles but also at dielectric and semiconducting nanomaterials. We employed hexagonal ZnO nanoplates to achieve near-field photocatalysis based on Mie resonance.9 The ZnO nanoplates were adsorbed onto a glass plate, and irradiated with linearly polarized UV light for reductive deposition of silver. The optical near field was localized at sites corresponding to the polarization direction of the irradiated light. Namely, silver deposition site can be controlled by the polarization angle (Figure 1c). Self-oxidative etching of the ZnO nanoplates themselves and oxidative deposition of cobalt oxide onto the ZnO nanoplates can also be conducted in the site-selective manner. Thus, near-field photocatalysis has been achieved via plasmon resonance and Mie resonance. The technique enables photonic nanofabrication beyond the diffraction limit and design of nanomaterials and nanodevices including sophisticated photocatalysts and metamaterials. A. Fujishima and K. Honda, Nature 238, 37-38 (1972). Y. Ohko, T. Tatsuma, T. Fujii, K. Naoi, C. Niwa, Y. Kubota, and A. Fujishima, Nature Mater. 2, 29-31 (2003). Y. Tian and T. Tatsuma, J. Am. Chem. Soc. 127, 7632-7637 (2005). T. Tatsuma, H. Nishi, and T. Ishida, Chem. Sci. 8, 3325-3337 (2017) [review]. S. H. Lee, H. Nishi, and T. Tatsuma, Phys. Chem. Chem. Phys. 21, 5674-5678 (2019). K. Saito, I. Tanabe, and T. Tatsuma, J. Phys. Chem. Lett. 7, 4363-4368 (2016). K. Saito and T. Tatsuma, Nano Lett. 18, 3209-3212 (2018). T. Tatsuma and H. Nishi, Nanoscale Horiz. 5, 597-606 (2020) [review]. Y. Oba, S. H. Lee, and T. Tatsuma, J. Phys. Chem. C 128, 827-831 (2024). Figure 1
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Zhang, Chen, Takuya Ishida, Seung Hyuk Lee, and Tetsu Tatsuma. "Synthesis and Characterization of Superparamagnetic CoPt Alloy Nanoparticles Exhibiting Magneto-Plasmonic Responses." ECS Meeting Abstracts MA2024-02, no. 67 (2024): 4595. https://doi.org/10.1149/ma2024-02674595mtgabs.

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Magnetic materials containing transition metals such as Fe, Co, and Ni have attracted considerable interest, in particular for their unique properties, which allow them to be applied to devices for magnetic control of optical communications and magneto-optical data storage. Magnetic control of catalysis and electrocatalysis is also a potential application of magnetic materials. Apparent catalytic activity can be controlled via a magnetohydrodynamic (MHD) effect, which affect mass transport rate in the vicinity of the magnetic material.[1] In addition, enantioselectivity can be given to the system by taking advantage of chiral-induced spin selectivity (CISS), which can be induced by magnetic materials.[2] If a magnetic material is broken down into nanoparticles, they could also obtain high catalytic activities. In addition, they would be superparamagnetic materials, which respond very rapidly to external magnetic fields without hysteresis. If the magnetic nanoparticles are metallic, they might exhibit magneto-optical responses such as magnetic circular dichroism (MCD), in association with localized surface plasmon resonance (LSPR).[3] LSPR would also allow the nanoparticles to be used for photocatalysis based on plasmon-induced charge separation (PICS).[4] These characteristics render magnetic nanomaterials suitable for catalysis, electrocatalysis, and photoelectrocatalysis with controllable activity and selectivity. With these points in mind, we synthesize superparamagnetic CoPt nanoparticles through a convenient wet chemical process[5] and examine their magneto-optical properties, more specifically, magnetic circular dichroism (MCD), in the UV-visible range. MCD characteristics would be important indices for magnetic materials to assess their magnetic properties including CISS. CoPt nanoparticles are well known for their high electrocatalytic activities as well as high magnetism due to strong spin-orbit interaction.[6] CoPt superlattice nanoparticles has been reported to show MCD in the near-infrared range and applied to magnetic switching of plasmonic laser.[7] However, MCD in the UV-visible range has not yet been reported for CoPt materials to the best of our knowledge. Co, Pt, and CoPt nanoparticles were synthesized via an oleylamine co-reduction method. Scanning electron microscopy (SEM) image shows that CoPt nanoparticles have a spherical shape with an average size of 6 nm (Fig. 1a). On the basis of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and superconducting quantum interference device (SQUID) analyses, we have confirmed that the synthesized CoPt nanoparticles have face-centered cubic (fcc) structure with a small amount of cobalt oxides at the particle surface of CoPt, and show superparamagnetism at room temperature. The magneto-optical properties of the Co, Pt, and CoPt nanoparticles were evaluated by a dissymmetry factor, g MCD-factor which was obtained by normalizing MCD with extinction. As shown in Fig. 1b, the Pt nanoparticles showed almost no MCD responses, and the Co nanoparticles exhibited very weak MCD responses, although the latter are magnetic. In contrast, the CoPt nanoparticles showed sufficiently strong MCD signals over the UV-visible range examined. The value of their g MCD-factor was approximately 0.034, which was in the range of very high g MCD-factor values. The possible origin of the MCD properties is circular electron motion in the metallic nanoparticle induced by circularly polarized light. It could also be coupled with circular mode of LSPR. In an external magnetic field, a Lorentz force is applied to the rotating charges, and the resonant light energy depends on the direction of the rotation, resulting in lifted degeneracy (Fig. 1c). Although this type of MCD is also observed for non-magnetic Au nanoparticles, introduction of a magnetic component to the nanosystem enhances the local magnetic field and thereby MCD responses. Likewise, the magnetism of Co would be positive for the MCD responses in the present system. In addition, the spin-orbit coupling induced by Pt may enhance the MCD responses further. [1] S. Luo, K. Elouarzaki, and Z. J. Xu, Angew. Chem. Int. Ed. 61, e202203564 (2022). [2] B. Göhler, V. Hamelbeck, T. Z. Markus, M. Kettner, G. F. Hanne, Z. Vager, R. Naaman, and H. Zacharias, Science 331, 894 (2011). [3] F. Pineider, G. Campo, V. Bonanni, C. d. J. Fernández, G. Mattei, A. Caneschi, D. Gatteschi, and C. Sangregorio, Nano Lett. 13, 4785 (2013). [4] Y. Tian and T. Tatsuma, J. Am. Chem. Soc. 127, 7632 (2005). [5] Y. Yu, W. Yang, X. Sun, W. Zhu, X.-Z. Li, D. J. Sellmyer, and S. Sun, Nano Lett. 14, 5, 2778 (2014). [6] J. Okabayashi, Y. Miura, and H. Munekata, Sci. Rep. 8, 8303 (2018). [7] F. Freire-Fernández, J. Cuerda, K. S. Daskalakis, S. Perumbilavil, J.-P. Martikainen, K. Arjas, P. Törmä, and S. van Dijken, Nat. Photon. 16, 27 (2022). Figure 1
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Fujii, Minoru, and Hiroshi Sugimoto. "(Invited) Mie Resonant Silicon Nanosphere Nanoantenna for Fluorescence Enhancement." ECS Meeting Abstracts MA2024-01, no. 23 (2024): 1356. http://dx.doi.org/10.1149/ma2024-01231356mtgabs.

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A nanoantenna is a device that manipulates light propagation and enhances light-matter interaction at the nanoscale. Integration of an emitter into a nanoantenna capable of increasing local density of photonic states at the emission wavelength results in the enhancement of the spontaneous emission rate (Purcell effect) and modifies the emission spectrum. A nanoantenna can also control the directionality and radiation pattern of an emitter. Traditionally, plasmonic nanoantennas made from gold or silver nanostructures supporting localized surface plasmon resonances had been the main stream of the nanoantenna research. Recently, high refractive index nanoparticles having low-order Mie resonances have been attracting attention as a new type of dielectric nanoantennas. Advantages of a dielectric nanoantenna compared to a plasmonic one are the smaller loss and the possession of magnetic type Mie resonances arising from light-induced displacement current. By properly controlling the overlap of the magnetic and electric multipole resonances, radiation patters of an emitter placed nearby can be tailored with high degree of freedom. Furthermore, magnetic-type Mie resonances can couple with higher-order optical transitions of an emitter such as a magnetic-dipole transition, and thus can enhance and control radiation from otherwise weak forbidden transitions. Recently, we have succeeded in producing perfectly spherical nanoparticles of crystalline silicon (Si) in 100-300 nm in diameters. These Si nanospheres exhibit the electric and magnetic multipole resonances at the optical frequency [1]. In this presentation, we first show scattering and absorption properties of the Mie resonant Si nanospheres. Especially, we show that solutions of size-purified Si nanospheres exhibit vivid structural color and the solutions can be used as structural color inks. We then show that the solutions can preserve helicity of incoming circularly-polarized light and can enhance local chiral fields around nanospheres [2, 3]. This property can be used to improve the sensitivity of enantiomer-selective chiral molecular sensing. We then show some examples of enhanced light-matter interaction by Si nanoparticles. These include enhancement of magnetic dipole transitions of an emitter by magnetic-type Mie resonances of Si nanospheres (magnetic Purcell effect) [4, 5], enhancement of excitation and emission processes of in-plane dipoles of monolayer transition metal dichalcogenides (TMDC) [6], and enhancement of a spin forbidden singlet-to-triplet absorption transition of a molecule by Si nanodisks [7, 8]. References [1] H. Sugimoto, et. al., "Mie Resonator Color Inks of Monodispersed and Perfectly Spherical Crystalline Silicon Nanoparticles", Advanced Optical Materials, 8 (2020) 2000033. [2] T. Hinamoto, et. al., “Colloidal Solutions of Silicon Nanospheres toward All-Dielectric Optical Metafluids”, Nano Letters, 20 (2020) 7737. [3] H. Negoro, et. al., “Helicity-Preserving Optical Metafluids”, Nano Letters, 23 (2023) 5101. [4] H. Sugimoto, and Minoru Fujii, "Magnetic Purcell Enhancement by Magnetic Quadrupole Resonance of Dielectric Nanosphere Antenna", ACS Photonics, 8 (2021) 1794. [5] H. Kasai, et. al., “Selective Enhancement of Crystal-Field-Split Narrow f-f Emission Lines of Europium Ions by Electric and Magnetic Purcell Effect of Mie Resonant Silicon Nanosphere”, Advanced Optical Materials (2023) (DOI: 10.1002/adom.202301204). [6] H. Shinomiya, et. al., “Enhanced Light Emission from Monolayer MoS2 by Doubly Resonant Spherical Si Nanoantennas”, ACS Photonics, 9 (2022) 1741. [7] H. Sugimoto, et. al., "Direct Excitation of Triplet State of Molecule by Enhanced Magnetic Field of Dielectric Metasurfaces", Small 17 (2021) 2104458. [8] H. Hasebe, et. al., “Photosensitizing Metasurface Empowered by Enhanced Magnetic Field of Toroidal Dipole Resonance”, Small, (2023) (DOI: 10.1002/smll.202302519).
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Yang, Xiu, Shanshan Huang, Rohit Chikkaraddy, et al. "Chiral Plasmonic Shells: High-Performance Metamaterials for Sensitive Chiral Biomolecule Detection." ACS Applied Materials & Interfaces, November 15, 2022. http://dx.doi.org/10.1021/acsami.2c16752.

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Sunaba, Yuji, Masaki Ide, Ryo Takei, Kyosuke Sakai, Christophe Pin, and Keiji Sasaki. "Nano-shaping of chiral photons." Nanophotonics, May 16, 2023. http://dx.doi.org/10.1515/nanoph-2022-0779.

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Abstract Localized surface plasmon polaritons can confine the optical field to a single-nanometer-scale area, strongly enhancing the interaction between photons and molecules. Theoretically, the ultimate enhancement might be achieved by reducing the “photon size” to the molecular extinction cross-section. In addition, desired control of electronic transitions in molecules can be realized if the “photon shape” can be manipulated on a single-nanometer scale. By matching the photon shape with that of the molecular electron wavefunction, optically forbidden transitions can be induced efficiently and selectively, enabling various unconventional photoreactions. Here, we demonstrate the possibility of forming single-nanometer-scale, highly intense fields of optical vortices using designed plasmonic nanostructures. The orbital and spin angular momenta provided by a Laguerre–Gaussian beam are selectively transferred to the localized plasmons of a metal multimer structure and then confined into a nanogap. This plasmonic nano-vortex field is expected to fit the molecular electron orbital shape and spin with the corresponding angular momenta.
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31

Massimo, Cuscuna, Manoccio Mariachiara, Esposito Marco, et al. "Gallium chiral nanoshaping for circularpolarization handling." June 7, 2021. https://doi.org/10.1039/d0mh01078b.

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In this work we report the local growth of ordered arrays of 3D core&ndash;shell chiral nanohelices based on plasmonic gallium metal. The structures can be engineered in a single step using focused ion beam induced deposition, where a Ga<sup>+</sup> ion source is used to shape the metallic nanohelix core, while the dielectric precursor is dissociated to create dielectric shells. The solubility of gallium in the different investigated dielectric matrices controls the core&ndash;shell thickness ratio of the nanohelices. The chiral plasmonic behaviour of these gallium-based nanostructures is experimentally measured by circularly polarized light transmission through nanostructure arrays and compared with numerical simulations. Large chiroptical effects in the visible range are demonstrated due to the plasmonic effects arising from gallium nanoclusters in the core.
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32

Huang, Shanshan, Siyi Wang, Xiu Yang, et al. "Ultrasensitive Ultraviolet Chiral Plasmonic Biosensor Based on Passivated Al Shells." ACS Applied Materials & Interfaces, May 1, 2025. https://doi.org/10.1021/acsami.5c02061.

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33

Wang, Fei, Zexiang Han, Juehan Sun, XueKang Yang, Xiaoli Wang, and Zhiyong Tang. "Reversible Ultrafast Chiroptical Responses in Planar Plasmonic Nano‐Oligomer." Advanced Materials, September 2023. http://dx.doi.org/10.1002/adma.202304657.

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Abstract(Ultracompact chiral plasmonic nanostructures with unique chiral light‐matter interactions are vital for future photonic technologies. However, previous studies are limited to reporting their steady‐state performance, presenting a fundamental obstacle to the development of high‐speed optical devices with polarization sensitivity. Here, we provide a comprehensive analysis of ultrafast chiroptical response of chiral gold nano‐oligomers using time‐resolved polarimetric measurements. We observe significant differences in terms of the absorption intensity, thus hot electron generation, and hot carrier decay time upon polarized photo‐pumping, which are explained by a phenomenological model of the helicity‐resolved optical transitions. Moreover, the chiroptical signal is switchable by reversing the direction of the pump pulse, demonstrating the versatile modulation of polarization selection in a single device. Our results offer fundamental insights into the helicity‐resolved optical transitions in photoexcited chiral plasmonics and could facilitate the development of high‐speed polarization‐sensitive flat optics with potential applications in nanophotonics and quantum optics.)This article is protected by copyright. All rights reserved
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34

Xie, Yuanyang, Alexey V. Krasavin, Diane J. Roth, and Anatoly V. Zayats. "Unidirectional chiral scattering from single enantiomeric plasmonic nanoparticles." Nature Communications 16, no. 1 (2025). https://doi.org/10.1038/s41467-024-55277-9.

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Abstract Controlling scattering and routing of chiral light at the nanoscale is important for optical information processing and imaging, quantum technologies as well as optical manipulation. Here, we introduce a concept of rotating chiral dipoles in order to achieve unidirectional chiral scattering. Implementing this concept by engineering multipole excitations in helicoidal plasmonic nanoparticles, we experimentally demonstrate enantio-sensitive and highly-directional forward scattering of circularly polarised light. The intensity of this highly-directional scattering is defined by the mutual relation between the handedness of the incident light and the chirality of the structure. The concept of rotating chiral dipoles offers numerous opportunities for engineering scattering from chiral nanostructures and optical nano-antennas paving the way for innovative designs and applications of chiral light-matter interactions.
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35

Yao, Chongyang, Huibin He, Weijia Kong, et al. "Polymer‐Driven Co‐Assembly of Achiral and Chiral Nanoparticles into Plasmonic Nanoclusters with Quantitatively Modulated Optical Chirality." Advanced Science, June 19, 2025. https://doi.org/10.1002/advs.202504850.

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AbstractChiral plasmonic nanoassemblies demonstrate enhanced chiral optical activity through plasmonic mode coupling, holding transformative potential for applications in sensing, catalysis, and quantum‐optical technologies. However, the mechanisms underlying this enhancement—particularly the roles of structural geometry, plasmonic coupling, and chiral field amplification—remain incompletely elucidated. A significant challenge persists in designing coupled nanoassemblies with precisely controlled nanostructures to systematically investigate chirality enhancement. Departing from conventional approaches that incorporate chiral molecules, we present the co‐assembly of achiral and chiral plasmonic nanoparticles (NPs) into ABn‐type nanoclustersand the correlation between inherent plasmonic chirality and the quantity of hotspots. Complementary polymer‐grafted achiral nanospheres and chiral nano arrows assemble into stable ABn clusters through a combination of electrostatic interactions and hydrogen bonding. The coordination number (n) of ABn can be tuned from 2 to 7 by adjusting polymer configurations through modulation of solution pH. The g‐factor of ABn exhibits a linear increase with the n value of ABn. Simulation results indicate that the enhanced optical chirality arises from the increase in electric field strength due to the increasing number of hotspots within the NP assemblies.
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36

Wang, Hanwei, and Yang Zhao. "Plasmon-enhanced chiral absorption through electric dipole-electric quadrupole interaction." Journal of Optics, June 3, 2024. http://dx.doi.org/10.1088/2040-8986/ad535e.

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Abstract Enantioselective interactions of chiral molecules include distinct absorptions to opposite-handed circularly polarized light, known as chiral absorption. Traditionally, chiral absorption has been primarily attributed to electric dipole and magnetic dipole interaction with molecular chirality. However, this approach falls short for large molecules that support high-order multipolar components, such as electric quadrupole moment. Here, we introduce a theoretical model to study the chiral absorption of large molecules in the presence of plasmonic nanostructures. This model considers both electric dipole-magnetic dipole interaction and electric dipole-electric quadrupole interaction enhanced by a resonant structure. We numerically study such interactions of the chiral molecular solution in the vicinity of a nonchiral plasmonic nano-resonator. Our results show the distinct spectral information of the chiral medium on- and off-resonance of the resonator.&amp;#xD;
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37

Kim, Juhwan, Jang‐Hwan Han, Hyun Min Kim, Tung‐Chun Lee, and Hyeon‐Ho Jeong. "Plasmonic Nano‐Rotamers with Programmable Polarization‐Resolved Coloration." Advanced Optical Materials, November 20, 2023. http://dx.doi.org/10.1002/adom.202301730.

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Abstract3D‐shaped artificial Mg nano‐rotamers with a programmable dihedral angle between two plasmonic arms, designed to exhibit both programmable linear and circular polarization properties, are presented. The nanoscale physical shadow growth technique offers precise control over the angular alignment in these nanostructures with 1° angular precision, thus controlling their symmetry from achiral C2v and C2h to chiral C2. As a result, they give rise to a wide range of polarization‐resolved coloration, spanning from invisible to visible colors with 46% transmission contrast for linear polarization while exhibiting 0.08 g‐factor in visible for circular polarization. These nano‐rotamers hold great potential for various applications in adaptive photonic filters, memory, and anticounterfeiting devices, benefiting from their tunable plasmonic properties.
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38

Raad, Shiva Hayati, Mehdi Afshari-Bavil, and Dong Liu. "Efficient and high-quality absorption enhancement using epsilon-near-zero cylindrical nano-shells constructed by graphene." Scientific Reports 14, no. 1 (2024). http://dx.doi.org/10.1038/s41598-024-55194-3.

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AbstractThis paper presents a detailed scattering analysis of a hollow-core plasmonic-shell cylindrical wire to design an efficient, compact, narrowband, and reconfigurable optical absorber. The shell is formed by a thin graphene material, investigated in its epsilon-near-zero (ENZ) plasmonic region. Compared to the graphene plasmonic resonances in the terahertz(THz)/far-infrared (FIR) frequencies, the ENZ plasmonic resonances offer a blue shift in the operating frequency of the second-order plasmonic resonances by increasing the geometrical dimensions. This feature is successfully used to design efficient optical wave absorbers with absorption cross-sections much larger than geometrical and scattering cross-sections. The observed blue shift in the resonance spectrum, which is the key point of the design, is further verified by defining each particle with its polarizability and fulfilling the resonant scattering condition in the framework of Mie’s theory. Furthermore, graphene relaxation time and chemical potential can be used to manipulate the absorption rate. Observed resonances have narrow widths, achieved with simple geometry. To consider more practical scenarios, the one-dimensional arrangement of the cylindrical elements as a dense and sparse array is also considered and the design key point regarding graphene quality is revealed. The quality factor of the sparse array resonance is 2272.8 and it demands high-quality graphene material in design. It is also observed that due to the use of small particles in the design, the near-field and cooperative effects are not visible in the absorption cross-section of the array and a clear single peak is attained. This polarization-insensitive absorber can tolerate a wide range of incident angles with an absorption rate above 90%.
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39

Zhang, Yan, Yemeng Sun, Xi Ren, et al. "Chiral Polar Bifunctional Polyimide Enantiomers for Asymmetric Photo‐ and Piezo‐catalysis." Angewandte Chemie, October 7, 2024. http://dx.doi.org/10.1002/ange.202416221.

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Chiral catalysts for asymmetric catalysis represent a crucial research focus in chemistry and materials science. However, a few cases about chiral‐dependent photocatalysts primarily focus on plasmonic noble metals. Particularly, developing chiral nano‐catalysts that can be driven by mechanical energy remains in the blank stage. Herein, organic polymer‐based enantiomers, chiral polar polyimide (PI) microspheric nano‐assembly are synthesized as novel bifunctional catalysts for asymmetric photocatalysis and piezocatalysis. The PI catalyst enantiomers present enantioselectivity towards left‐ and right‐circularly polarized light, demonstrating chiral‐dependent H2O2 photoproduction. Interestingly, enantioselectivity of the catalyst reverses under irradiation of different bands, presenting tunability in the interaction between chiral catalysts and circularly polarized light. For the first time, enantioselective piezocatalytic behavior is demonstrated by the chiral polar PI catalysts. They show remarkable chiral preference for asymmetric Diels‐Alder reaction and enantioselective conversion of tyrosine substrates under ultrasonic vibration. The findings provide a new perspective into exploring metal‐free chiral catalysts and their asymmetric catalysis applications across multiple energy forms.
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40

Zhang, Yan, Yemeng Sun, Xi Ren, et al. "Chiral Polar Bifunctional Polyimide Enantiomers for Asymmetric Photo‐ and Piezo‐catalysis." Angewandte Chemie International Edition, October 7, 2024. http://dx.doi.org/10.1002/anie.202416221.

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Chiral catalysts for asymmetric catalysis represent a crucial research focus in chemistry and materials science. However, a few cases about chiral‐dependent photocatalysts primarily focus on plasmonic noble metals. Particularly, developing chiral nano‐catalysts that can be driven by mechanical energy remains in the blank stage. Herein, organic polymer‐based enantiomers, chiral polar polyimide (PI) microspheric nano‐assembly are synthesized as novel bifunctional catalysts for asymmetric photocatalysis and piezocatalysis. The PI catalyst enantiomers present enantioselectivity towards left‐ and right‐circularly polarized light, demonstrating chiral‐dependent H2O2 photoproduction. Interestingly, enantioselectivity of the catalyst reverses under irradiation of different bands, presenting tunability in the interaction between chiral catalysts and circularly polarized light. For the first time, enantioselective piezocatalytic behavior is demonstrated by the chiral polar PI catalysts. They show remarkable chiral preference for asymmetric Diels‐Alder reaction and enantioselective conversion of tyrosine substrates under ultrasonic vibration. The findings provide a new perspective into exploring metal‐free chiral catalysts and their asymmetric catalysis applications across multiple energy forms.
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41

Zhang, Yingjie, Junqing Li, Rui Zhao, and Xingguang Liu. "Characteristics of surface plasmonic modes in cylindrical chiral-graphene-dielectric waveguide structure." Journal of Physics D: Applied Physics, November 29, 2022. http://dx.doi.org/10.1088/1361-6463/aca6f4.

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Abstract A cylindrical chiral-graphene-dielectric waveguide structure is proposed. Correspondingly, characteristics of surface plasmonic mode are theoretically investigated, including dispersion relation, intensity, phase and polarization distribution. The proposed waveguide can only support the vortex modes with the hybrid polarization distribution, which originates from the spin-momentum locking of evanescent electromagnetic waves. The circular birefringence of chiral materials releases the degeneracy between same-order vortex modes. In addition, the number of modes can be controlled by changing the radius of the dielectric nanowire and the Fermi level of graphene. The effective index and corresponding propagation length of the mode are sensitive to the chiral parameter. We believe the proposed waveguide can find some potential applications in multiplex communication, chiral sensing and the fabrication of tunable nano-photonic devices.
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42

Huang, Xuedong, Qian Shi, Yanwei Lu, et al. "Single‐Molecule Electrochemiluminescence Imaging of Plasmonic Hot Spot Reactivity." Angewandte Chemie International Edition, July 2, 2025. https://doi.org/10.1002/anie.202508266.

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Localized surface plasmon resonance (LSPR), an important optical property of noble metal nanomaterials, is extensively applied in electrochemistry. However, the specific LSPR effects on metallic nanoparticles are difficult to unravel and evaluate owing to simultaneous factors like intrinsic electroactivity and surface interactions. Herein, we designed a series of shell‐isolated nanostructures, with mesoporous silica shells and plasmonic Au Nanorod cores (AuNR@mSiO2), for precisely investigating both LSPR and nanoconfinement effects. Single‐molecule electrochemiluminescence (ECL) imaging was employed to monitor the in situ turnover frequency (TOF) of photon emissions on individual plasmonic nano‐amplifiers to determine the dominant factors influencing LSPR and nanoconfinement effects. TOF heatmaps and super‐resolution ECL images unveiled distinct hot spot distributions along the plasmonic nanostructures. Our approach provides insight into and in‐depth understanding of plasmonic effects during electrochemical reactions, thereby facilitating precise electrocatalyst design based on the physiochemical properties of LSPR.
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43

Huang, Xuedong, Qian Shi, Yanwei Lu, et al. "Single‐Molecule Electrochemiluminescence Imaging of Plasmonic Hot Spot Reactivity." Angewandte Chemie, July 2, 2025. https://doi.org/10.1002/ange.202508266.

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Localized surface plasmon resonance (LSPR), an important optical property of noble metal nanomaterials, is extensively applied in electrochemistry. However, the specific LSPR effects on metallic nanoparticles are difficult to unravel and evaluate owing to simultaneous factors like intrinsic electroactivity and surface interactions. Herein, we designed a series of shell‐isolated nanostructures, with mesoporous silica shells and plasmonic Au Nanorod cores (AuNR@mSiO2), for precisely investigating both LSPR and nanoconfinement effects. Single‐molecule electrochemiluminescence (ECL) imaging was employed to monitor the in situ turnover frequency (TOF) of photon emissions on individual plasmonic nano‐amplifiers to determine the dominant factors influencing LSPR and nanoconfinement effects. TOF heatmaps and super‐resolution ECL images unveiled distinct hot spot distributions along the plasmonic nanostructures. Our approach provides insight into and in‐depth understanding of plasmonic effects during electrochemical reactions, thereby facilitating precise electrocatalyst design based on the physiochemical properties of LSPR.
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44

Qin, Jin, Xiaofei Wu, Anke Krueger, and Bert Hecht. "Light-driven plasmonic microrobot for nanoparticle manipulation." Nature Communications 16, no. 1 (2025). https://doi.org/10.1038/s41467-025-57871-x.

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Abstract Recently light-driven microdrones have been demonstrated, making use of plasmonic nanomotors based on directional resonant chiral light scattering. These nanomotors can be addressed individually, without requiring the tracking of a focused laser, leading to exceptional 2D maneuverability which renders microdrones a versatile robotic platform in aqueous environments. Here, we incorporate a light-operated manipulator, a plasmonic nano-tweezer, into the microdrone platform, rendering it a microrobot by enabling precise, all-optical transport and delivery of single nanoparticles suspended in solution. The plasmonic nano-tweezer consists of a resonant cross-antenna nanostructure exhibiting a central near-field hot spot, extending the ability of traditional optical tweezers based on focused laser beams to the trapping of nanoparticles. However, most of plasmonic nano-tweezers are fixed to the substrates and lack mobility. Our plasmonic microrobot utilizes circularly polarized light to control both motors and for stable trapping of a 70-nanometer fluorescent nanodiamond in the cross-antenna center. Complex sequences of microrobot operations, including trap-transport-release-trap-transport actions, demonstrate the microrobot’s versatility and precision in picking up and releasing nanoparticles. Our microrobot design opens potential avenues in advancing nanotechnology and life sciences, with applications in targeted drug delivery, single-cell manipulation, and by providing an advanced quantum sensing platform, facilitating interdisciplinary research at the nanoscale.
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45

Wang, Qifa, Jiahe Liu, Chenyang Li, et al. "On‐Demand Fabrication and Manipulation of Single Plasmonic Trimers for Ultrasensitive Enantiomer Detection." Advanced Functional Materials, October 25, 2024. http://dx.doi.org/10.1002/adfm.202412985.

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AbstractThe capability of plasmonic nanostructures in generating superchiral near‐fields holds great potential for a wide range of applications, including enantioselective sensing, medical diagnosis, and chirality‐based bioimaging. To implement high‐performance chiral nanophotonic devices, achieving in situ tuning of chiroptical activity in plasmonic nanostructures is highly desirable yet remains a formidable challenge. Here, a straightforward method is developed for deterministic assembly of plasmonic nanosphere trimers using spectroscopy‐assisted nano‐manipulation. The technique offers in situ, real‐time, and site‐specific control over the chiroptical response of trimers by adjusting their vertex angle and in‐plane orientation. The combination of numerical simulations with the Born‐Kuhn model reveals that oblique excitation effectively induces the symmetry breaking of the trimer structure, resulting in a preferential response of two distinct hybridized plasmonic modes to the handedness of light. Consequently, this yields a significant chiroptical response with the g factor up to 0.37. Remarkably, the trimer with an optimized obtuse angle exhibits a 193‐fold enhancement of optical chirality density, enabling the detection of molecular chirality with a record‐large spectral dissymmetric factor of 12 nm. The study facilitates the rational design of plasmonic nanostructures, offering promising prospects for chiral sensing at the single‐molecule level and asymmetric photocatalysis.
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46

Hussain, Shahid, Xueyu Guan, Ruonan Ji, and Shao-Wei Wang. "Ultra-wideband chiroptical response by tri-layer anisotropic plasmonic metamaterial." Journal of Physics D: Applied Physics, October 24, 2023. http://dx.doi.org/10.1088/1361-6463/ad066d.

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Abstract The use of plasmonic chiral metamaterials for the control of circular polarization has the potential to replace conventional optical equipment for the polarization-related applications. The ultra-broadband chiroptic response using plasmonic constituents is delivered by elaborate three-dimensional (3D) helical structures, nevertheless, their implementation is complicated, time-consuming, and poses a significant scaling difficulty at the nano level. Ultra-broadband response from planar constituents is particularly necessary as a means to circumvent the challenges of 3D metamaterials. Here we present a planar plasmonic structure composed of tri-layer anisotropic arrays constituting nanowires and cut-wires to generate dual overlapped chiral bands. Based on this tri-layer approach, we numerically realized ultra-broadband planar plasmonic metamaterials to function in the near- and mid-infrared regions with a bandwidth range of 1.38–3.07 µm and 4.00–8.10 µm, and maximum circular dichroism performance of 0.90 and 0.92 respectively. The structures are ultracompact, misalignments tolerant, and can be extended to additional spectral regions through structural engineering. The proposed metamaterial has the potential to be used in the creation of ultra-compact, high-performance devices for a wide variety of uses, such as those in the fields of optical communication, biological diagnosis, high-contrast polarization imaging, high-accuracy polarimetric measurements, and spectroscopy.
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47

Ghamari, Shahin, Hsin-Yu Wu, Srikanth Pedireddy, and Frank Vollmer. "Plasmonic nanorod and dimer chiral molecule sensing from cysteine monolayer to bi-layers and multilayered shells." npj Biosensing 2, no. 1 (2025). https://doi.org/10.1038/s44328-025-00036-z.

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48

Huang, Shanshan, Shilin Xian, Jialong Peng, Xiu Yang, Jinglei Du, and Yidong Hou. "Long‐Range Disorder MetaSurface Enabled High‐Performance One‐Shot Ultraviolet Full‐Stokes Polarimeter." Laser & Photonics Reviews, August 22, 2024. http://dx.doi.org/10.1002/lpor.202400784.

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AbstractThe rapidly‐developed nanophotonics enable the realization of highly‐precise, ultra‐compact full Stokes polarimeters. However, realizing large‐area well‐designed structures with complex chiral morphology and subwavelength size is still a challenge to the current micro/nano‐engineering technology. Here, one high‐performance, ultra‐compact, and one‐shot full‐Stokes polarimeters in the ultraviolent waveband for the first time based on the long‐range disorder chiral shells fabricated by the micro‐sphere lithography are experimentally demonstrated. This chiral–shell monolayer owns strong and distinct optical chirality and anisotropy between the shells in adjacent micro‐domains and thus leads to different photo‐electric responses to the incident polarized lights for the photodetectors placed underneath. Through employing the residual convolutional neural network to extract the Stokes parameter , a small detection averaged mean square error (MSE) of &lt;0.5% from 316 nm to 410 nm is realized, and the minimum MSEs at 361 nm can reach recorded values of ≈0.02% (), 0.017% (), and 0.014% (). The influence of exposure time and pixel number, and the system stability are systematically investigated. This work brings new inspiration for the disorder structures based on Bottom‐Up methods, high‐performance polarimeters, and polarization imaging devices.
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49

Petronijevic, Emilija, T. Cesca, C. Scian, et al. "Demonstration of extrinsic chirality in self-assembled asymmetric plasmonic metasurfaces and nanohole arrays." Scientific Reports 14, no. 1 (2024). http://dx.doi.org/10.1038/s41598-024-68007-4.

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AbstractChirality, the lack of mirror symmetry, can be mimicked in nanophotonics and plasmonics by breaking the symmetry in light-nanostructure interaction. Here we report on versatile use of nanosphere lithography for the fabrication of low-cost metasurfaces, which exhibit broadband handedness- and angle-dependent extinction in the near-infrared range, thus offering extrinsic chiro-optical behavior. We measure wavelength and angle dependence of the extinction for four samples. Two samples are made of polystyrene nanospheres asymmetrically covered by silver and gold in one case and silver only in the other case, with a nanohole array at the bottom. The other two samples are nanohole arrays, obtained after the nanosphere removal from the first two samples. Rich extrinsic chiral features are governed by different chiro-optical mechanisms in the three-dimensional plasmonic semi-shells and planar nanohole arrays. We also measure Stokes parameters in the same wavelength and incidence angle range and show that the transmitted fields follow the extrinsic chirality features of the extinction dissymmetry. We further study the influences of the nanostructured shapes and in-plane orientations on the intrinsic vs extrinsic chirality. The nanoholes are modelled as oval shapes in metal, showing good agreement with the experiments. We thus confirm that nanosphere lithography can provide different geometries for chiral light manipulation at the nanoscale, with the possibility to extend functionalities with optimized oval shapes and combination of constituent metals.
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50

Cognée, Kévin G., Hugo M. Doeleman, Philippe Lalanne, and A. F. Koenderink. "Cooperative interactions between nano-antennas in a high-Q cavity for unidirectional light sources." Light: Science & Applications 8, no. 1 (2019). http://dx.doi.org/10.1038/s41377-019-0227-x.

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AbstractWe analyse the resonant mode structure and local density of states in high-Q hybrid plasmonic-photonic resonators composed of dielectric microdisks hybridized with pairs of plasmon antennas that are systematically swept in position through the cavity mode. On the one hand, this system is a classical realization of the cooperative resonant dipole–dipole interaction through a cavity mode, as is evident through predicted and measured resonance linewidths and shifts. At the same time, our work introduces the notion of ‘phased array’ antenna physics into plasmonic-photonic resonators. We predict that one may construct large local density of states (LDOS) enhancements exceeding those given by a single antenna, which are ‘chiral’ in the sense of correlating with the unidirectional injection of fluorescence into the cavity. We report an experiment probing the resonances of silicon nitride microdisks decorated with aluminium antenna dimers. Measurements directly confirm the predicted cooperative effects of the coupled dipole antennas as a function of the antenna spacing on the hybrid mode quality factors and resonance conditions.
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