[en] A strong coupling regime between propagating surface plasmons (PSPs) and the dark resonant mode in a metallic nano-dimer and film structure spaced with a dielectric layer is theoretically demonstrated. Compared with the reported coupling scheme based on bright mode-PSPs interaction, larger mode splitting and stronger anticrossing are presented in the dispersion diagram. At the same time, a hybridized mode consisting of short-range surface plasmons on the dimer and longe-range surface plasmons on the metallic film is observed. The results indicate that the plasmonic dispersion could be tuned flexibly by introducing coupling between the dark mode and PSPs, which provides a significant tool for the design of future plasmonic nanodevices and metamaterials. (paper)

[en] To investigate the effect of a reagent's rotational and vibrational excitations on the stereo-dynamics of the reaction product, the title reaction is theoretically simulated using the quasi-classical trajectory (QCT) method on the ³A″ and ³A′ potential energy surfaces (PESs). The reaction cross section is considered as the only scalar property in this work at four different collision energies. Furthermore the vector properties including two polarization-dependent differential cross sections (PDDCSs), the angular distributions of product' rotational momentum are discussed at one fixed collision energy. Effects of reagents' rotational excitation on the reaction do exist regularly

[en] A tunable dual-band stop-band THz spectrum can be realized in a hybrid structure, which consists of metal nanoribbon arrays clad by graphene nanoribbons. Dual-band spectra can be controlled separately by the nanoribbon width w and graphene chemical potential μ_c. We explain that two local plasmonic modes excited at graphene ribbons belong to different gratings, which uncouple with each other by electro-magnetic shielding of the metal ribbons. Furthermore, plasmonic induced transparent (PIT) effects can also be realized by making the two transmission notches close to each other, with better performance than the PIT system based on plasmonic coupling, such as with a larger extinction radio and a tunable transparency window. (paper)

[en] We have investigated the resonant properties of a composite meander wire array, which is composed of physically connected ‘metamolecules’ each with two face-to-face hetero-connected split-ring resonators (SRRs). The hybridization of the symmetric modes and antisymmetric modes of the two hetero-connected SRRs results in four resonant modes in the isolated ‘metamolecule’. In the chain case however, only the hybridized symmetric modes, the so-called optical modes, exist, leading to the observed trapped modes. These two trapped modes show an opposite frequency shift between the chain and isolated metamolecule. Numerical simulations and a theoretical analysis based on the hybridization model are used to interpret the underlying physics of the above observation. Our results provide a further understanding of the hybridization effect in complex metamaterials. The continuous morphology of our double-chain structure may be applied tp the design of reconfigurable metamaterials and flexible devices. (paper)

[en] Suitable solvent additives provide an effective means to control the morphology of polymer blend films. In this work, we systematically investigate the impact of the solvent additive chloronaphthalene (CN) on the morphology of P3HT : EP-PDI blends. The optimum volume fraction of solvent additive CN was found to be 0.5 vol% by atom force microscopy and transmission electron microscopy. UV–visible absorption spectroscopy and grazing incidence x-ray diffraction indicate that the crystallinity of both the P3HT and EP-PDI domains significantly decreased in the blends with 0.5 vol% CN. Grazing incidence small-angle x-ray scattering results show that the size of the small EP-PDI aggregation decreases from 44–22 nm with the addition of CN. Time-resolved photoluminescence measurement reveals that the decreased EP-PDI domains give rise to increased donor–acceptor interfacial areas, which not only facilitate the exciton dissociation, but suppresses the formation of the EP-PDI intermolecular state. (paper)

[en] The coupling between the high order localized resonant mode and diffraction mode in meta-molecule arrays consisting of three identical split ring resonators (SRRs) in each cell was demonstrated numerically with finite difference time domain method. By introducing both the near-field interaction and diffraction coupling mechanism, two types of interesting resonant modes are observed. One is the excitation of the second and the third-order plasmon resonance simultaneously with linear polarized light at normal incidence. The other one is a dark plasmonic state with sharper line shape produced by the third-order plasmon resonance and diffraction coupling. These resonant modes based on the ‘designed’ coupling scheme present higher quality factors than those in hybridized plasmonic state due to the electric dipole interaction, which is of great interest for application in the field of nanophotonic devices such as sensing, detector and spaser. (paper)

[en] The non-linear responses of optical materials offer useful mechanisms for optical switching, novel optical sources, and harmonic frequency conversion. However, the non-linear response of traditional materials is usually extremely weak and requires high input power for excitation. In this study, we theoretically propose a scheme for enhancing the third harmonic generation (THG) efficiency and output power of layered graphene disks array by introducing a plasmonic antibonding state with enhanced oscillation strength due to plasmonic coupling. We verify that, the THG efficiency of a double-layer stacked graphene/SiO₂ disk structure under relatively low input intensity can be significantly enhanced more than one order of magnitude with appropriate design, as compared with monolayer patterned graphene nanostructure. We also demonstrate that the THG efficiency can be further improved by optimizing the geometry parameters such as spacer distance and Fermi energy. Our results offer an effective mechanism for significantly improving THG efficiency in the mid-infrared and terahertz ranges, thereby paving the way for new frequency converters and modulators in optical communication and signal processing. (paper)

[en] We propose and numerically analyze an ultra-compact tunable plasmon ring resonator which is composed of monolayer graphene and a graphene ring. The results, calculated using the finite element method, reveal that the resonant frequency can be tuned over a wide frequency range by a small change of Fermi level in the graphene ring. Both a high quality factor and extinction ratio of the resonant mode can be achieved when the plasmonic waves in the ring and the input waveguide are properly coupled. As applications, this proposed resonator can be used to construct an ultra-compact fast-tunable filter, modulator, switch or directional coupler in the mid-infrared range. (paper)

[en] We propose and numerically analyze a terahertz tunable plasmonic directional coupler which is composed of a thin metal film with a nanoscale slit, dielectric grating, a graphene sheet, and a dielectric substrate. The slit is employed to generate surface plasmon polaritons (SPPs), and the metal-dielectric grating-graphene-dielectric constructs a Bragg reflector, whose bandgap can be tuned over a wide frequency range by a small change in the Fermi energy level of graphene. As a graphene-based Bragg reflector is formed on one side of the slit, the structure enables SPP waves to be unidirectionally excited on the other side of the slit due to SPP interference, and the SPP waves in the Bragg reflector can be efficiently switched on and off by tuning the graphene's Fermi energy level. By introducing two optimized graphene-based Bragg reflectors into opposite sides of the slit, SPP waves can be guided to different Bragg reflectors at different Fermi energy levels, thus achieving a tunable bidirectional coupler.

[en] Two new d¹⁰ based coordination polymers having formula [Cd(HL1)(L2)] (1) and [Zn(HL1)(L2)] (2) (H₃L1=5-(4-carboxyphenoxy)isophthalic acid and L2=3-(4-methyl-6-(pyridine-3-yl)pyridine-2-yl)pyridine) have been synthesized and characterized using IR, thermogravimetric analyses (TGA), photoluminescence and single-crystal X-ray diffraction techniques. The single-crystal X-ray investigation reveals that both of 1 and 2 show 2D layer architectures with square lattice topology. The photoluminescence investigation indicates that both 1 and 2 could be a prospective candidate for developing luminescence sensors for the highly sensing of nitroaromatic analytes. Furthermore, the luminescent property of 1 and 2 in different solvents analytes as well as nitrobenzene derivative have been investigated and the observed quenching in fluorescence have been corroborated by theoretical calculations. - Graphical abstract: Two new d¹⁰-based luminescent MOFs synthesized and their sensing properties towards different nitroaromatics investigated.