The chirality and chiroptical response of materials have attracted significant attention for their potential to introduce the new science of light-matter interactions. We demonstrate that collective mode formation under modal coupling between localized surface plasmon resonances (LSPRs) with a chiral arrangement and Fabry-Pérot (FP) nanocavity modes can induce chiroptical responses. We fabricated a cluster of isotropic gold nanodisks with a chiral arrangement (gold nano-windmills, Au-NWs) on the FP nanocavities of TiO and Au film.
View Article and Find Full Text PDFStudies on chiral spectroscopy have recently demonstrated strong enhancement of chiral light-matter interaction in the chiral near-field of Mie resonance in high-refractive-index dielectric nanostructures by studies on chiral spectroscopy. This situation has motivated researchers to demonstrate effective chiral photosynthesis under a chiral near-field beyond circularly polarized light (CPL) as a chiral source. However, the effectivity of the chiral near-field of Mie resonance for chiral photosynthesis has not been clearly demonstrated.
View Article and Find Full Text PDFWe developed a substrate that enables highly sensitive and spatially uniform surface-enhanced Raman scattering (SERS). This substrate comprises densely packed gold nanoparticles (d-AuNPs)/titanium dioxide/Au film (d-ATA). The d-ATA substrate demonstrates modal ultrastrong coupling between localized surface plasmon resonances (LSPRs) of AuNPs and Fabry-Pérot nanocavities.
View Article and Find Full Text PDFDiversity in structures of water endowed by a hydrogen-bonding network plays crucial roles in wide varieties of phenomena in nature. Chiral ordering of water molecules is an intriguing phenomenon from the viewpoint of bimolecular functions. However, experimental reports on chiral ordering have been limited to the water molecules interacting with biomolecules on the molecular scale.
View Article and Find Full Text PDFDepending on the photoirradiation conditions, metal nanostructures exhibit various plasmonic modes, including dipolar, quadrupolar, and hexapolar modes. This work demonstrates numerically that these high-order plasmonic modes can be used to switch nanoscale temperature distributions during the plasmonic heating of a manganese (Mn) nanorod. The key feature of Mn is its low thermal conductivity.
View Article and Find Full Text PDFExpression of concern for 'Versatile plasmonic-effects at the interface of inverted perovskite solar cells' by Ahmed Esmail Shalan, , , 2017, , 1229-1236, https://doi.org/10.1039/C6NR06741G.
View Article and Find Full Text PDFWe fabricate a novel photoanode consisting of TiO/Au nanoparticles (Au-NPs)/GaO/TiN/Au-film (TAGA), efficiently increasing light absorption and electron transfer from Au-NPs to GaO under modal strong coupling. A TiN thin layer deposited on an Au film enables stable high-temperature deposition of GaO onto the reflective Au film mirror. Modal strong coupling is observed when the resonance wavelength of the GaO/TiN/Au-film Fabry-Pérot cavity overlaps with the plasmon resonance wavelength of Au-NPs partially inlaid in a thin TiO layer.
View Article and Find Full Text PDFHot-hole injection from plasmonic metal nanoparticles to the valence band of p-type semiconductors and reduction by hot electrons should be improved for efficient and tuneable reduction to obtain beneficial chemical compounds. We employed the concept of modal strong coupling between plasmons and a Fabry-Pérot (FP) nanocavity to enhance the hot-hole injection efficiency. We fabricated a photocathode composed of gold nanoparticles (Au-NPs), p-type nickel oxide (NiO), and a platinum film (Pt film) (ANP).
View Article and Find Full Text PDFThe optical near field (NF) induced by circularly polarized light (CPL) is a hot scientific topic. We observed a chiral NF intensity distribution on a series of achiral gold nanorectangular structures (Au-NRs) under CPL irradiation by using multiphoton photoemission electron microscopy (MP-PEEM). Additionally, the differential NF spectra under left and right CPL irradiation, which represent the asymmetry of the NF intensity distribution, were investigated.
View Article and Find Full Text PDFWe developed a photoanode consisting of Au-Ag alloy nanoparticles (NPs), a TiO thin film and a Au film (AATA) under modal strong coupling conditions with a large splitting energy of 520 meV, which can be categorized into the ultrastrong coupling regime. We fabricated a photoanode under ultrastrong coupling conditions to verify the relationship between the coupling strength and photoelectric conversion efficiency and successfully performed efficient photochemical reactions. The AATA photoanode showed a 4.
View Article and Find Full Text PDFThe spatiotemporal origin of plasmonic chiroptical responses in nanostructures remains unexplored and unclear. Here, two orthogonally oriented Au nanorods as a prototype were investigated, with a giant chiroptical response caused by antisymmetric and symmetric mode excitations for obliquely incident left-handed circular polarization (LCP) and right-handed circular polarization (RCP) light. Time-resolved photoemission electron microscopy (PEEM) was employed to measure the near-field spatial distributions, spectra, and spatiotemporal dynamics of plasmonic modes associated with the chiroptical responses at the nanofemto scale, verifying the characteristic near-field distributions at the resonant wavelengths of the two modes and a very large spectral dichroism for LCP and RCP.
View Article and Find Full Text PDFWe experimentally demonstrate and theoretically study the formation of coherent plasmon-exciton states which exhibit absorption of >90% of the incident light (at resonance) and cancellation of absorption. These coherent states result from the interaction between a material supporting an electronic excitation and a plasmonic structure capable of (near) perfect absorption of light. We illustrate the potential implications of these coherent states by measuring the charge separation attainable after photoexcitation.
View Article and Find Full Text PDFIn this study, an interfacial modification layer was applied to improve the plasmon-induced light energy conversion of a gallium(iii) oxide (Ga2O3) photoelectrode, which possesses a much more negative conduction band potential compared with the reduction potential of photons to hydrogen. The plasmon-induced photocurrent generation under visible light irradiation was observed with Au nanoparticle-loaded Ga2O3 (Au-NPs/Ga2O3). An interfacial modification was carried out by depositing a titanium dioxide (TiO2) thin-film layer on Au-NPs/Ga2O3via atomic layer deposition.
View Article and Find Full Text PDFLocalized surface plasmon resonances (LSPRs) are gaining considerable attention due to the unique far-field and near-field optical properties and applications. Additionally, the Fermi energy, which is the chemical potential, of plasmonic nanoparticles is one of the key properties to control hot-electron and -hole transfer at the interface between plasmonic nanoparticles and a semiconductor. In this article, we tried to control the diffusion potential of the plasmonic system by manipulating the interface dipole.
View Article and Find Full Text PDFStrong coupling between two resonance modes leads to the formation of new hybrid modes exhibiting disparate characteristics owing to the reversible exchange of information between different uncoupled modes. Here, we realize the strong coupling between the localized surface plasmon resonance and surface plasmon polariton Bloch wave using multilayer nanostructures. An anticrossing behavior with a splitting energy of 144 meV can be observed from the far-field spectra.
View Article and Find Full Text PDFStrong coupling between plasmons and optical modes, such as waveguide or resonator modes, gives rise to a splitting in the plasmon absorption band. As a result, two new hybrid modes are formed that exhibit near-field enhancement effects. These hybrid modes have been exploited to improve light absorption in a number of systems.
View Article and Find Full Text PDFIn the molecular world, molecular ratchets can realize the unidirectional movement in molecular machines. However, construction of artificial molecular ratchets has been still a great challenge. In this study, we investigate the formation of pseudo-rotaxane of a newly designed two-station axis molecule with α-cyclodextrin (α-CD) and the deuteration of acidic protons in the axis in DO by H NMR at varying temperatures.
View Article and Find Full Text PDFMetallic nanoparticles such as silver and gold show localized surface plasmon resonances (LSPRs), which are associated with near-field enhancement effects in the vicinity of nanoparticles. Therefore, strong light-matter interaction is induced by the near-field enhancement effects of LSPRs. Because the resonant wavelength of LSPRs can be easily controlled by the size and shape of the metallic nanoparticles in the visible and near-infrared wavelength range, LSPRs have received considerable attention as optical antennae for light energy conversion systems such as solar cells.
View Article and Find Full Text PDFWe investigated the grating effect in complex gold dolmen structures, in which multiple plasmon modes are present due to plasmon hybridization, experimentally from both the far field and the near field. In particular, the near-field properties were investigated using photoemission electron microscopy, and it was demonstrated that two hybridized plasmon modes on the dolmen structures could be influenced by the grating effect. For comparison, we also investigated the grating effect in arrays of simple nanoblocks and heptamer structures, which were supposed to support a strong bright plasmon mode and a strong dark plasmon mode, respectively, in the near field.
View Article and Find Full Text PDFWe developed a localized surface plasmon-induced visible light-responsive photoelectrochemical (PEC) biosensor using a titanium dioxide (TiO) photoelectrode loaded with gold nanoislands (AuNIs) for in situ real-time measurement of biotin-streptavidin association. As a proof of concept, self-assembled thiol-terminated biotin molecules bound on a AuNIs/TiO photoelectrode were successfully utilized to explore the photocurrent response to streptavidin-modified gold nanoparticle (STA-AuNP) solutions. This plasmon-induced PEC biosensor is simple and easy to miniaturize.
View Article and Find Full Text PDFPlasmonics is a highly promising approach to enhancing the light-harvesting properties of hybrid organic/inorganic perovskite solar cells. In the present work, our cells have a p-i-n inverted planar structure. An ultrathin NiO film with two different thicknesses of 5 and 10 nm prepared by a pulsed laser deposition process on an ITO substrate with a faceted and furrowed surface enabled the formation of a continuous and compact layer of well-crystallized CHNHPbIvia an anti-solvent chlorobenzene process.
View Article and Find Full Text PDFCoO is a promising hole-extracting layer (HEL) for inverted planar perovskite solar cells with device configuration ITO/CoO/CHNHPbI/PCBM/Ag. The devices fabricated according to a simple solution procedure showed the best photovoltaic performance attaining power conversion efficiency (PCE) of 14.5% under AM 1.
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