Resonance Hybrid Research Articles

Revisiting the Redox Transitions of Polyaniline. Semiquantitative Interpretation of Electrochemically Induced IR Bands

• Quantification of redox forms of polyaniline. • Octameric model for PANI transitions. • Back to aniline-black structures. The redox transitions of PANI in acidic medium have been monitored by a combination of cyclic voltammetry, in situ conductance and in situ FTIR spectroscopy. The results of the semiquantitative analysis strongly suggest that the classical tetrameric model of PANI does not satisfactorily describe the actual structures of the polymer at different redox states. An octameric model is revisited, with the inclusion of essential resonant structures, to provide an appropriate prediction of the relative IR intensity changes of the aromatic C C stretching (at around 1520 cm −1 ) and the quinoid C C stretching (at around 1590 cm −1 ) vibrations observed by FTIR, which are difficult to interpret by considering only 4 aniline rings. Particularly, it is found that the emeraldine state is better described as a resonance hybrid of the classical bipolaronic and semiquinoid (polaron lattice) structures, while most of the charge transferred at the onset of the second voltammetric peak comes from the additional oxidation of this hybrid, which becomes unstable in the electrochemical environment producing mineralization to CO 2 and release of soluble quinones.

Photoactivation of ambient oxygen via plasmon-coupled valence-band hybridization in AgPd nanoalloy for reaction pathway alteration

To achieve green, economic, and selective catalytic oxidation processes for pathway-controllable chemical synthesis, the activation of molecular oxygen is a crucial requirement but faces thermodynamic challenges. Here we show that the synergy of the plasmon resonance and valence-band hybridization exciting both interband and intraband transitions in nanoalloys is a promising strategy for O2 dissociation and reaction pathway alteration at mild conditions. For the oxidation of benzyl alcohol over AgPd nanoalloys, at compositions with Ag content around the Golden Ratio and under visible illumination we observe >95 % selectivity to esters, which is superior to that at other compositions or in the dark. The plasmon-coupled valence-band hybridization promotes the generation of atomic oxygen species at near room temperature, driving the direct oxidative esterification and reducing the aldehyde formation. These results exemplify a predictable design for the electronic structure regulation in plasmonic nanoalloys to develop new reaction pathways via photoactivation of reactants.

Coherent Pulse Echo in Hybrid Magnonics with Multimode Phonons

The hybridization of magnons and phonons is playing a critical role in the emerging field of hybrid magnonics because it combines the high tunability of magnetism with the long lifetime of mechanics for comprehensive coherent information processing. Recently there has been increasing interest in thin-film bulk acoustic waves because of their long lifetimes at high frequencies. However, the unique multimode nature of such phonon modes has not been exploited as an important resource for coherent information processing. In this Letter we study the simultaneous hybridization of multiple high-overtone bulk acoustic resonances with a magnon and a microwave mode. The demonstrated multimode hybridization allows us to observe coherent pulse echoes, opening opportunities for both fundamental studies and practical applications of hybrid magnonics.

Ultrathin hybrid absorber based on high-order metamaterial

In this work, we utilized a hybrid resonator to achieve near-perfect and dual-band absorption in the VHF and the LTE/Bluetooth/WiMAX bands. An electromagnetic (EM) wave at an oblique incidence was captured efficiently by exciting the fundamental magnetic resonances at 106 and 123.4 MHz. In particular, the effective thickness of the metamaterial perfect absorber (in comparison with the working wavelength ) is miniaturized to be at the high-order resonances (induced in the 2.0–4.0 GHz range) at a specific incident angle of EM wave, = 45°, 30°, 15° and = 5°. Our results contribute to the realization of meta-devices, such as sensors, optical filters/switchers, photodetectors, and energy converters, for future applications in the radio to the microwave frequency bands.

Factors in Protobiomonomer Selection for the Origin of the Standard Genetic Code.

Natural selection of specific protobiomonomers during abiogenic development of the prototype genetic code is hindered by the diversity of structural, spatial, and rotational isomers that have identical elemental composition and molecular mass (M), but can vary significantly in their physicochemical characteristics, such as the melting temperature Tm, the Tm:M ratio, and the solubility in water, due to different positions of atoms in the molecule. These parameters differ between cis- and trans-isomers of dicarboxylic acids, spatial monosaccharide isomers, and structural isomers of α-, β-, and γ-amino acids. The stable planar heterocyclic molecules of the major nucleobases comprise four (C, H, N, O) or three (C, H, N) elements and contain a single -C=C bond and two nitrogen atoms in each heterocycle involved in C-N and C=N bonds. They exist as isomeric resonance hybrids of single and double bonds and as a mixture of tautomer forms due to the presence of -C=O and/or -NH2 side groups. They are thermostable, insoluble in water, and exhibit solid-state stability, which is of central importance for DNA molecules as carriers of genetic information. In M-Tm diagrams, proteinogenic amino acids and the corresponding codons are distributed fairly regularly relative to the distinct clusters of purine and pyrimidine bases, reflecting the correspondence between codons and amino acids that was established in different periods of genetic code development. The body of data on the evolution of the genetic code system indicates that the elemental composition and molecular structure of protobiomonomers, and their M, Tm, photostability, and aqueous solubility determined their selection in the emergence of the standard genetic code.

Resonant multi-soliton, M-breather, M-lump and hybrid solutions of a combined pKP-BKP equation

In the present paper, first, resonant multi-soliton solutions of a combined pKP-BKP equation were obtained by carrying out the linear superposition principle and a group of 3D and contour images vividly represent the process of wave motion with physical interpretation. Next, M-breather solutions including 1-breather, 2-breather, 3-breather and hybrid solutions between breather and soliton have been constructed with their dynamic characters and physical structure via the complex conjugate method and symbolic computation. Finally, by combining the long wave limit method and the complex conjugate method in term of N-soliton solutions, M-lump solutions including 1-lump, 2-lump and 3-lump and two types of hybrid solutions between lumps and solitons were obtained. In addition, several groups of images exhibited their dynamic structure and physical properties with physical interpretation via symbolic computation. Furthermore, the obtained results have immensely augmented the exact solutions of a combined pKP-BKP equation on the available literature and enabled us to understand the nonlinear dynamic system deeply.

Magnetically tuned hybrid resonance emission of terahertz waves from the interaction of intense laser beams with warm collisional inhomogeneous plasma

Enhancing the terahertz emission at hybrid resonant frequencies is observed from a warm collisional inhomogeneous plasma irradiated by intense laser beams in the presence of an external transverse magnetic field. To reach this result, we utilize the dielectric permittivity tensor of the plasma affected by the strength and the direction of the magnetic field and analyze the nonlinear current density induced by the ponderomotive force due to the beating of two Gaussian laser beams. The calculations reveal resonance emission at several frequencies, which depend on the thermal speed of the electrons, the wavenumber, the electron plasma frequency, the collision frequency, and the cyclotron frequency. However, the amplitude of THz waves at these frequencies mainly depends on the electron temperature as well as the external magnetic field strength.

Optical activity in resonant hybrid photonic crystals and clusters

Optical activity in resonant hybrid photonic crystals and clusters

Quasi‐Ordered Nanoforests with Hybrid Plasmon Resonances for Broadband Absorption and Photodetection

AbstractWith the continuing development of green energy technology, solar energy is the most widely distributed and easily utilized form of energy in nature. High‐absorption absorbers over a wide spectrum range are beneficial for solar energy harvest. Herein, a fast and efficient method is developed to fabricate a broadband absorber consisting of quasi‐ordered nanoforests and metal nanoparticles using a simple plasma bombardment process on a 4‐inch silicon wafer, offering high throughputs that can meet practical application demands. The absorber exhibits high absorption exceeding 90% from 300 to 2500 nm, good absorption stability with negligible disturbance from the polarization and the incident angle of light. This effective absorption behavior can be ascribed to multilevel hybridization of the plasmon resonances in the hybrid structures and cavity mode resonances inside the nanoforests. Furthermore, the absorber is integrated onto a thermopile for photodetection with largely enhanced photoresponse from 532 to 2200 nm. The photoinduced voltage of the devices shows a large increment of 433% at 100 mW cm−2 light power density, in comparison with a contrast pristine thermopile. It is expected that such a broadband absorber holds great potential for multiple applications, including solar steam generation, photodetection, and solar cells.

High Q-Factor Hybrid Metamaterial Waveguide Multi-Fano Resonance Sensor in the Visible Wavelength Range.

We propose a high quality-factor (Q-factor) multi-Fano resonance hybrid metamaterial waveguide (HMW) sensor. By ingeniously designing a metal/dielectric hybrid waveguide structure, we can effectively tailor multi-Fano resonance peaks’ reflectance spectrum appearing in the visible wavelength range. In order to balance the high Q-factor and the best Fano resonance modulation depth, numerical calculation results demonstrated that the ultra-narrow linewidth resolution, the single-side quality factor, and Figure of Merit (FOM) can reach 1.7 nm, 690, and 236, respectively. Compared with the reported high Q-value (483) in the near-infrared band, an increase of 30% is achieved. Our proposed design may extend the application of Fano resonance in HMW from mid-infrared, terahertz band to visible band and have important research value in the fields of multi-wavelength non-labeled biosensing and slow light devices.

Ultra High Q and Widely Tunable Mie Resonance Nanofilter at Telecom Wavelengths

Mie resonators offer a novel way for the subwavelength localization of light, showing large local field enhancement without metal optical absorption. In this paper, an ultra-high quality factor Q and widely tunable Mie resonance nanofilter at telecom wavelengths is presented. The loss mechanisms in this hybrid resonators are systematically analyzed. A selected high-index Ge disk embedded at the center of plasmonic nanocavity acts well as a Mie resonator for coupling the incident light. Based on the theoretical analysis and modeling, a widely tunable spectra linewidth from 14.2 nm to 1.2 nm and the maximum corresponding Q as high as 1292 is achieved. The Mie resonance nanofilters provide the possibility to make high performance and practical resonance component for nanophotonics integration.

A Miniaturized Ka-Band Bandpass Filter Using Folded Hybrid Resonators Based on Monolithic Microwave Integrated Circuit Technology

A miniaturized Ka-band bandpass filter (BPF) is presented by using monolithic microwave integrated circuit (MMIC) technology in this brief. Aiming at low cost and high integration, small die area of MMIC BPFs is significantly required for RF front-end modules.However, the filtering performance of BPFs is negatively correlated to its miniaturization. To this end, the folded hybrid resonator is investigated in this brief, which is composed of a quasi-lumped capacitor and a distributed microstrip line. To realize miniaturization, two metal layers of GaAs process are fully utilized. For low loss, the distributed inductor is designed on the top thick layer, while the quasi-lumped capacitor is on the lower metal layer of high sheet resistance. To reduce the unwanted mutual coupling between adjacent quasi-lumped capacitors, shielding structures are added into BPFs, resulting in a 5-dB and 12-dB enhancement to the lower and upper stopbands, respectively. Based on the mixed electric-magnetic coupling topology, a second-order MMIC bandpass filter is designed and fabricated by using GaAs process. Small die area, low loss, high selectivity, and wide stopband are simultaneously obtained, indicating a promising application of the proposed miniaturized MMIC bandpass filters.

Light–matter interactions in the coupling system of quantum emitter and hyperbolic nanorod

Plasmonic nanostructures are widely applied to couple with quantum emitters (QEs), so as to improve the optical performances of QE and obtain advanced photonic devices, such as the quantum photon source, quantum circuit. However, the huge loss of plasmonic nanostructures greatly hinders the future development of plasmon–QE hybrid systems. Herein, we propose the hyperbolic nanorods (HNR) which are built by alternate Au and SiO2 thin layers. The size of HNR discussed in this paper is mainly around 40 × 50 × 60 nm3, which is a subwavelength size benefiting for device miniaturization and integration. The photonic resonant mode of HNR can be tuned by simply changing its length/width ratio. Due to the hybridization of the surface plasmon polariton resonances associated with each metal–dielectric interface, the HNR possesses the advantage of small mode volume (V) as the Au plasmonic nanorod (PNR) with similar size, and its mode quality factor (Q) can be larger due to the lower loss. Therefore, when coupled with a resonant QE, the Purcell factor in HNR/QE is ∼20 times larger than that in the PNR/QE system. Furthermore, the HNR/QE hybrid also demonstrates obvious superiority over the PNR/QE in generating strong coupling and quantum entanglement. With the features of small V and low loss, it is believed that the HNR can not only greatly improve the optical properties of QE, but also be a powerful nanostructure for studying light–matter interactions.

Anomalous hybridization complementation effect on phonon transport in heterogeneous nanowire cross junction

Controlling phonon transport via its wave nature in nanostructures can achieve unique properties for various applications. In this paper, thermal conductivity of heterogeneous nano cross junction (hetero-NCJ) is studied through molecular dynamics simulation. It is found that decreasing or increasing the atomic mass of four side wires (SWs) severed as resonators, thermal conductivity of hetero-NCJ is enhanced, which is larger than that of homogeneous NCJ (homo-NCJ). Interestingly, by setting two SWs with larger atomic mass and other two SWs with smaller atomic mass, thermal conductivity of hetero-NCJ is abnormally decreased, which is even smaller than that of homo-NCJ. After further non-equilibrium Green’s function calculations, it is demonstrated that origin of increase is attributed to the hybridization broken induced by unidirectional shift of resonant modes. However, the decrease in thermal conductivity originates from hybridization complementation induced by bidirectional shift of resonant modes, which synergistically blocks phonon transport. This work provides a mechanism for further strengthening resonant hybridization effect and manipulating thermal transport.

Dual Nanoresonators for Ultrasensitive Chiral Detection.

The discrimination of enantiomers is crucial in biochemistry. However, chiral sensing faces significant limitations due to inherently weak chiroptical signals. Nanophotonics is a promising solution to enhance sensitivity thanks to increased optical chirality maximized by strong electric and magnetic fields. Metallic and dielectric nanoparticles can separately provide electric and magnetic resonances. Here we propose their synergistic combination in hybrid metal–dielectric nanostructures to exploit their dual character for superchiral fields beyond the limits of single particles. For optimal optical chirality, in addition to maximization of the resonance strength, the resonances must spectrally coincide. Simultaneously, their electric and magnetic fields must be parallel and π/2 out of phase and spatially overlap. We demonstrate that the interplay between the strength of the resonances and these optimal conditions constrains the attainable optical chirality in resonant systems. Starting from a simple symmetric nanodimer, we derive closed-form expressions elucidating its fundamental limits of optical chirality. Building on the trade-offs of different classes of dimers, we then suggest an asymmetric dual dimer based on realistic materials. These dual nanoresonators provide strong and decoupled electric and magnetic resonances together with optimal conditions for chiral fields. Finally, we introduce more complex dual building blocks for a metasurface with a record 300-fold enhancement of local optical chirality in nanoscale gaps, enabling circular dichroism enhancement by a factor of 20. By combining analytical insight and practical designs, our results put forward hybrid resonators to increase chiral sensitivity, particularly for small molecular quantities.

Optimizing thermal transport in graphene nanoribbon based on phonon resonance hybridization

As a critical way to modulate thermal transport in nanostructures, phonon resonance hybridization has become an issue of great concern in the field of phonon engineering. In this work, we optimized phonon transport across graphene nanoribbon and obtained minimized thermal conductance by means of designing nanopillared nanostructures based on resonance hybridization. Specifically, the optimization of thermal conductance was performed by the combination of atomic Green's function and Bayesian optimization. Interestingly, it is found that thermal conductance decreases non-monotonically with the increase of number for nanopillared structure, which is severed as the resonator and blocks phonon transport. Further mode-analysis and atomic Green's function calculations revealed that the anomalous tendency originates from decreased phonon transmission in a wide frequency range. Additionally, nonequilibrium molecular dynamics simulations are performed to verify the results with the consideration of high-order phonon scattering. This finding provides novel insights into the control of phonon transport in nanostructures.

Dynamical characteristics of the piezotronic ZnO nanowire device in ballistic transport and its MEMS/NEMS resonator hybrid

In this work, the dynamical analysis of carrier transportation in a typical piezoelectric device working in the ballistic regime is conducted. Based on the quantum scatting theory, the Poisson and Schrödinger equations are combined for calculating the dynamical transmission coefficient of the metal–piezoelectric ZnO–metal structure subject to sinusoidal and rectangular external stresses. The roles played by the spanning width of induced piezopotential and incident electron energy in affecting transmission probability are further discussed and clarified, respectively. The cutoff frequency of the piezoelectric device is also studied. Moreover, MEMS/NEMS hybrids specified by double/single-clamped ZnO quantum wire micro/nano-electromechanical resonator hybrids are proposed. Through a comprehensive numerical simulation, it is revealed that the rich nonlinear dynamics of the resonator can be subtly transferred to the piezoelectric device, and the chaotic transmission in the piezoelectric device can arise in two-dimensional parameter space with respect to time and incident electron energy. Therefore, the hybrids are endowed with the ability to detect amplitude changes by measuring ultra-sensitive quantum tunneling current. The study sheds light on developing quantum piezotronics and its related MEMS/NEMS integrations.

Hybrid multi-resonators elastic metamaterials for broad low-frequency bandgaps

Elastic metamaterials with multi-degree-of-freedom (MDOF) hybrid resonators are proposed in order to achieve the lower and wider bandgaps without increase of mass for vibration attenuation in this paper. The explicit expressions for the central frequencies of the bandgaps of the multi-resonators elastic metamaterials (EMs) are analyzed for the first time to exploring broad low-frequency bandgap. The boundary frequencies of the bandgaps are initiatively obtained analytically to seek for the wider bandgap, which comply with the natural frequencies of the unit cell with its free or fixed ends. The bandgap forming mechanism is explored by dispersion curve and relative movement of the masses. Besides, the condition for bandgap merging is obtained for broad bandgap generation. Finally, the band structure of the three classes of proposed models with hybrid resonators with the same total mass are compared with the classical EMs model (MODEL T), revealing that the central frequencies of bandgap of proposed models become lower, or the total width of the bandgap is significantly widened. The Hybrid Series MODEL Ⅱ achieves 14.5% lower and 81% wider bandgap while Hybrid Parallel MODEL Ⅱ achieves 163% wider bandgap than that of classical local resonance EMs (MODEL T) with the same mass and stiffness.

A robust scheme for unidirectional emission from a hybrid whispering gallery cavity system based on transformation optics.

Using the transformation cavity, a gradient index cavity designed by transformation optics, we propose a hybrid resonator system to extract unidirectional narrow-beam emission from high-Q whispering gallery modes by embedding a transformation cavity inside a deformed uniform index cavity that exhibits unidirectional narrow-beam emission. For effective mode coupling between the transformation cavity and enclosing cavity, the embedded transformation cavity is designed to have bidirectional evanescent emission, which enables most of the emission from the transformation cavity to be laterally incident on the rim of the enclosing deformed cavity. Consequently, ultrahigh-Q resonances of this system can provide a sharp free-space light output, which is difficult to achieve by embedding a homogeneous disk cavity instead of the transformation cavity.

The effect of gain-assisted silica separate layer on the plasmonic local field enhancement of Ag-Si-Ag coaxial-cable type silver nanotube

The plasmonic local electric field enhancement characters of gain-assisted coaxial-cable type Ag-Si-Ag nanotube have been investigated computationally. The calculation results based on quasi-static analysis indicate that the three surface plasmon resonance (SPR) hybridization modes depend on the gain medium of the silica separate layer in different ways. The SPR band from antisymmetric coupling between bonding tube plasmon mode and the wire plasmon mode (denoted as peak3) is mostly sensitive to the gain assist, and the greatest local field enhancement factor of 104 could be achieved with a critical gain coefficient. The physical mechanism has been attributed to the appearance of the local field hot spot in silica separate layer, in which the gain medium has been dropt. The critical gain coefficient could be tuned by altering the geometry factors of the nanostructure. It has been found that the thickness of the middle silica nanolayer with gain medium greatly affect the critical gain coefficient. For peak3, the maximum plasmonic field enhancement could be easily achieved with a small gain coefficient and within a slight change region. Whereas for SPR band from the symmetric coupling between the bonding tube plasmon mode and the wire plasmon mode (denoted as peak2), the local field hot spot appears in the inner Ag nanowire without gain medium. Thus the maximum plasmonic field enhancement could only be achieved with a large gain coefficient when the middle nanolayer with gain medium has a thin thickness.