Resonance Properties Research Articles

Properties of charge-exchange giant spin-dipole resonances in medium-heavy closed-shell parent nuclei: A semimicroscopic description

Properties of charge-exchange giant spin-dipole resonances in medium-heavy closed-shell parent nuclei: A semimicroscopic description

Spin‐Thermoelectric Generation Associated with Magnetization Dynamics in the Insulator‐Based Generators Fabricated from Liquid Phase Epitaxial Yttrium Iron Garnet, Bi‐Substituted YIG and Bi‐ and Al‐Substituted YIG Films

An insulator‐based spin‐thermoelectric (STE) generator is composed of a thin paramagnetic metal (PM: Pt) layer for generating the STE voltage VSTE via the inverse spin Hall effect and a ferrimagnetic insulator (FMI) film or slab used for producing spin‐wave spin currents due to a temperature gradient . Yttrium iron garnet (YIG) is a key material used for the FMI of STE generators. We examined in detail the ferromagnetic resonance (FMR) properties of YIG (Y3Fe5O12), Bi‐substituted YIG (Y3‐xBixFe5O12) and Bi‐ and Al‐substituted YIG (Y3‐xBixFe5‐yAlyO12) films grown by liquid phase epitaxy (LPE). Bi‐substituted YIG films exhibited the large FMR damping and high STE voltage when the films were incorporated in the STE generator. The LPE‐grown Y2.35Bi0.65Fe5O12 film exhibited the FMR linewidth ΔH of 30 mT and the VSTE of 70 μV for the ∇T of . This paper comprehensively presents the origin of the STE generation in the insulator‐based generators on the basis of the results of FMR and STE measurements. To clarify the origin of STE generation in the generators fabricated from single crystal YIG (YIG, Bi‐substituted YIG and Bi‐ and Al‐substituted YIG) films grown by LPE, three principal factors are explained: (a) thermal energy transfer from the phonon system to the spin system, which strengthens the heat excitation of spin precession, through the spin–orbit coupling enhanced by the growth‐induced magnetic anisotropy of LPE‐grown YIG films, (b) in the YIG films incorporated in the STE generators, the generation of spin‐wave spin currents owing its origin to the ferromagnetic spin exchange interaction acting between neighboring spins due to , and (c) how the spin currents pumped into the Pt layer from the YIG film at the Pt/YIG bilayer interface are affected by the magnetization processes of single crystal YIG films. It is concluded that the STE generation of insulator‐based STE generators can be explained from a viewpoint of the spin dynamics under the effect of in the Pt/YIG bilayer structure. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Flower-like Cu9S5 and magnetic NiCo@C particles synergize to build three-dimensional conductive networks for efficient electromagnetic wave absorption

To increase the use of sulfides in electromagnetic wave absorption, researchers are continuously developing thin semiconductor sulfide absorbers with significant absorption capacity and wide bandwidth. In this study, we synthesized NiCo@C/Cu9S5 materials with the dual loss mechanism (dielectric and magnetic losses) by evenly loading magnetic NiCo@C particles on flower-like Cu9S5 matrixes utilizing the magnetic derivatization technique for metal-organic frameworks (MOFs). The three-dimensional flower-like structures of the composites, intrinsic properties of the materials, and the resulting three-dimensional conductive network endow the material with multiple scattering and reflection, conduction loss, resonance, and eddy current properties. The synergistic effect of these loss pathways leads to the outstanding electromagnetic wave (EMW) absorption performance of the materials. The results show that the minimum reflection loss (RLmin) of NiCo@C/Cu9S5 can reach −52.83 dB when the matching thickness is 2.09 mm. Meanwhile, the maximum effective absorption band (EAB) is 5.1 GHz (12.3–17.4 GHz) at a matching thickness of 1.69 mm. Furthermore, the radar cross section (RCS) of the absorbers has been calculated by CST Studio Suite, demonstrating the ability of the absorbent coating to lower the RCS at different angles efficiently. These discoveries provide new insights for high-performance sulfide electromagnetic wave absorbers and contribute to electromagnetic wave energy storage and conversion studies.

Visible light active Ag@SrTiO3: A powerful photocatalyst for NOx degradation

Exploiting visible light for NOx degradation represents an important challenge to enhance the air quality of our environment. In the present study, the photocatalytic activities of two commercial strontium titanate (STO) having different sizes (micro and nano) were compared towards NOx degradation under LED light. The decoration of both STO photocatalysts by Ag nanoparticles (8 theoretical wt.%) led to enhanced photocatalytic efficiency more than twice. In particular, nano-sized Ag@STO showed the highest activity (75% of NOx degradation) within 180 min due to Ag nanoparticles (NPs) localized surface plasmon resonance (LSPR) properties and the large surface area of nano-STO. The photocatalysts were synthesized by the wet impregnation method and calcined at 400 °C. Their structural, morphological, specific surface area, and optical properties were characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), N2 adsorption/desorption analysis, and UV–Vis diffuse reflectance spectroscopy (DRS).

Dynamic Properties of Coupled Nonlinear Split-Ring Resonators

In this paper, we delve into the dynamics of two and three coupled SRRs models, exploring their nonlinear properties such as stability, periodicity, or chaos. Additionally, we examine the energy function Hamilton within the context of these models. Numerical examples are provided to illustrate the obtained results and demonstrate the applicability of our findings.

Self‐doped conjugated polymers with electron‐deficient quinone units for enhanced electron transport in highly efficient organic solar cells

AbstractOrganic solar cells (OSCs) have attracted significant attention as a burgeoning flexible technology, owing to their advanced power conversion efficiencies. Moreover, interface materials play a crucial role in optimizing energy level alignment between the active layer and electrodes, thereby enhancing carrier extraction within the device and improving efficiency. However, current methodologies for fabricating electron‐transport materials with superior mobility are still limited compared with those for hole‐transport materials. In this study, a benzodifurandione (BFDO)‐derived building block with quinone resonance property and strong electron‐withdrawing capability was synthesized. Two conjugated polymers, namely PBFDO‐F6N and PBFDO‐F6N‐Br, were prepared, both of which exhibited good electron mobility and exceptional interface modification capabilities. A comprehensive investigation of the interaction between the interface layer and the active layer revealed that PBFDO‐F6N induced doping at the acceptor interface. Additionally, the high mobility of PBFDO‐F6N facilitated efficient carrier extraction at the interface. Consequently, the application of PBFDO‐F6N as the cathode interface layer for PM6:BTP‐eC9‐based OSC devices resulted in a remarkable efficiency of 18.11%. Moreover, the device efficiency remained at ∼96% even at a PBFDO‐F6N interface thickness of 50 nm, demonstrating the great potential of this material for large‐scale device preparation.

Flexural-Mode Piezoelectric Resonators: Structure, Performance, and Emerging Applications in Physical Sensing Technology, Micropower Systems, and Biomedicine.

Piezoelectric material-based devices have garnered considerable attention from scientists and engineers due to their unique physical characteristics, resulting in numerous intriguing and practical applications. Among these, flexural-mode piezoelectric resonators (FMPRs) are progressively gaining prominence due to their compact, precise, and efficient performance in diverse applications. FMPRs, resonators that utilize one- or two-dimensional piezoelectric materials as their resonant structure, vibrate in a flexural mode. The resonant properties of the resonator directly influence its performance, making in-depth research into the resonant characteristics of FMPRs practically significant for optimizing their design and enhancing their performance. With the swift advancement of micro-nano electronic technology, the application range of FMPRs continues to broaden. These resonators, representing a domain of piezoelectric material application in micro-nanoelectromechanical systems, have found extensive use in the field of physical sensing and are starting to be used in micropower systems and biomedicine. This paper reviews the structure, working principle, resonance characteristics, applications, and future prospects of FMPRs.

Biogenic synthesis of selenium nanoparticles from Nyctanthes arbor-tristis L. and evaluation of their antimicrobial, antioxidant and photocatalytic efficacy

Biogenic synthesis of nanoparticles has been established as an environmentally benign and sustainable approach. This study emphasizes biosynthesis of selenium nanoparticles (SeNPs) utilizing leaf extract of Nyctanthes arbor-tritis L., well known for its abundant bioactive compounds. Various analytical techniques were employed for characterization of synthesized SeNPs. X-ray diffraction (XRD) spectroscopy confirmed the crystalline structure and revealed the average crystalline size of SeNPs to be 44.57 nm. Additionally, UV–Vis spectroscopy confirmed successful synthesis of SeNPs by validating the surface plasmon resonance (SPR) properties of SeNPs. FTIR analysis data revealed different bonds and their corresponding functional groups responsible for the synthesis and stability of synthesized SeNPs. DLS and zeta analysis revealed that 116.5 nm sized SeNPs were stable in nature. Furthermore, field emission scanning electron microscopy (FE-SEM) validated the spherical morphology of SeNPs with a size range of 60–80 nm. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) determined the concentration of SeNPs in the obtained colloidal solution. Antioxidant activity of synthesized SeNPs was evaluated employing DPPH and H2O2 assay, revealed that the synthesized SeNPs were effective antioxidant agent. Additionally, antimicrobial potential was evaluated against a panel of Gram-positive and Gram-negative bacteria and found to be effective at higher concentration of SeNPs. SeNPs also exhibited strong anti-biofilm activity while evaluated against various biofilm producing bacteria like Escherichia coli,Staphylococcus epidermidis and Klebsiella pneumonia. The cytotoxicity of the bio-synthesized SeNPs was evaluated against HEK 293 cell line, exhibited minimal toxicity even at concentration 100 μg/mL with 65% viable cells. SeNPs has also been evaluated for dye degradation which has indicated excellent photocatalytic activity of synthesized SeNPs. The experimental data obtained altogether demonstrated that synthesized SeNPs exhibited significant antimicrobial and anti-biofilm activity against various pathogens, and also showed significant antioxidant and photocatalytic efficiency.

Water holding-capacity and flavor improvement of prepared meat patties induced by magnetic field-assisted marinating and preheating

Magnetic field (MF)-assisted technology is considered a potentially effective approach to improve the edible quality of meat products. This study aims to investigate various parameters (0 mT–4.5 mT) of MF-assisted marinating and preheating processes on the water-holding capacity and flavor of prepared meat patties. Analyzing cooking loss, low-field nuclear magnetic resonance, emulsion stability, and rheological properties confirmed that the water-holding capacity of meat patties rises initially and then falls with increasing MF strength during two processes (marinating and preheating processes). Furthermore, MF-assisted processing boosts sulfur compounds production in meat patties, resulting in higher concentrations of keto alcohols such as 2-heptanone, ethanol, and amyl alcohol, which contribute positively to the flavor and sensory properties. Overall, an appropriate MF intensity with 3.0 mT for 3 h at marinating and with 4.5 mT for 45 min at preheating could enhance the water-holding capacity and flavor of prepared meat patties, indicating promise for the meat industry.

Combined TL and EPR study to elucidate the origin of luminescent emission from La-doped CaF2 phosphor

This paper presents the results of the combined study of the thermoluminescence (TL) and electron paramagnetic resonance (EPR) properties of La-doped CaF2 (CaF2: La) phosphor. X-ray diffraction (XRD) results confirmed that CaF2 has been successfully synthesized. Scanning electron microscopy (SEM) results and energy dispersive spectrometer (EDS) spectra show that the synthesized phosphor is pure and has a good overall morphology. The glow curve of CaF2: La phosphor shows an emission band between 230 and 500 nm centered at 340 nm. The Tm-Tstop method and the deconvolution technique were used to find the number of overlapping TL peaks in the 50–300 °C region and their kinetic parameters. A linear dose-response curve was obtained for the range 1–9 Gy, with the onset of a slight supralinear behavior for doses higher than 9 Gy. Gamma-irradiated CaF2: La phosphor has been studied using the technique of EPR to identify the defect centers and also to infer the centers involved in the TL process. Thermal annealing studies indicate the presence of three defect centers. One of the centers (center I) is identified as the O2− ion and is characterized by an axial g-tensor with principal values g∥ = 2.013 and g⊥ = 2.0053. This center correlates with the TL peak at 200 °C. Center II with an isotropic g-value of 2.0005 is attributed to an F center and also relates to the 200 °C TL peak. The third center (center III) is assigned to an F center.

Design and calculation of photoelectric properties of resonance enhanced InAs/GaSb type-II superlattices photodetectors with diffraction rings structure

The resonance enhanced InAs/GaSb type-II Superlattices (T2SLs) infrared detectors with diffraction rings is designed, and the photoelectric characteristics are calculated and studied in this paper. The diffraction rings are designed on the top surface of T2SLs detector to control the incident light inside the device by forming the resonant cavity. We designed the structure of the conventional PIN InAs/GaSb T2SLs photodetector, calculated the energy band structure of the absorption layer, and analyzed the influence of the thickness of the absorption layer on the photoelectric performance. It is proved that blindly increasing the thickness of the absorption layer cannot effectively improve the device performance. We further studied the quantum efficiency (QE) and electric field distribution of the device after adding the diffraction ring structure. The results show that the structure with diffraction rings can significantly improve the QE of the photodetector without increasing the dark current. The interaction between the diffraction ring and the metal contact layer will enhance the localization of the electric field and further increase the light absorption between the semiconductor layers.

Coupling organic free-radical molecules to lumped-element superconducting resonators

A promising route toward the realization of a molecular spin quantum processor relies on coupling magnetic molecules to individual photons confined within superconducting resonators. As a simple approximation to such a hybrid scheme, here we explore the conditions that determine the collective coupling of DPPH organic free radicals to lumped-element LC superconducting resonators. In these chips, multiple resonators are coupled to a single readout line. This enables designing the relevant resonator properties, such as resonance frequency, cavity volume, and impedance while keeping a perfect transmission for the device. Here, we exploit these design possibilities to achieve a coherent spin-photon coupling regime. Besides, we study how this coupling depends on the relative orientation of the external dc magnetic field concerning the photon magnetic field and the spins locations concerning the chip surface.

On the Development of a Near-Shore Pivoting Wave Energy Converter

Numerous offshore wave energy converter (WEC) designs have been invented; however, none has achieved full commercialization so far. The primary obstacle impeding WEC commercialization is the elevated levelized cost of energy (LCOE). Consequently, there exists a pressing need to innovate and swiftly diminish the LCOE. A critical challenge faced by WECs is their susceptibility to extreme wave loads during storms. Promising concepts must demonstrate robust design features to ensure resilience in adverse conditions, while maintaining efficiency in harnessing power under normal sea states. It is anticipated that the initial commercial endeavors will concentrate on near-shore WEC technologies due to the cost advantages associated with proximity to the coastline, facilitating more affordable power transmission and maintenance. In response, this manuscript proposes a pioneering near-shore WEC concept designed with a survivability mode that is engineered to mitigate wave loads during severe sea conditions. Moreover, prior investigations have highlighted favorable resonance properties of this novel concept, enhancing wave power extraction during recurrent energetic sea states. This study employs numerical and physical modelling techniques to evaluate wave loads on the proposed WEC. The results indicate a remarkable 65% reduction in wave loads on the moving floater of the WEC during a range of sea states under the implemented survivability mode.

The Weis-Fogh Number Describes Resonant Performance Tradeoffs in Flapping Insects.

Dimensionless numbers have long been used in comparative biomechanics to quantify competing scaling relationships and connect morphology to animal performance. While common in aerodynamics, few relate the biomechanics of the organism to the forces produced on the environment during flight. We discuss the Weis-Fogh number, N, as a dimensionless number specific to flapping flight, which describes the resonant properties of an insect and resulting tradeoffs between energetics and control. Originally defined by Torkel Weis-Fogh in his seminal 1973 paper, N measures the ratio of peak inertial to aerodynamic torque generated by an insect over a wingbeat. In this perspectives piece, we define N for comparative biologists and describe its interpretations as a ratio of torques and as the width of an insect's resonance curve. We then discuss the range of N realized by insects and explain the fundamental tradeoffs between an insect's aerodynamic efficiency, stability, and responsiveness that arise as a consequence of variation in N, both across and within species. N is therefore an especially useful quantity for comparative approaches to the role of mechanics and aerodynamics in insect flight.

Seismic wave amplification in a weakly nonlinear two-layered soil deposit

Based on numerous observations, local soil site conditions can significantly affect the formation of seismic responses. In this paper, we examine seismic responses caused by shear waves propagating through a two-layered soil deposit. The aim of the research is to study the phenomenon of amplification of shear waves due to the resonant properties of the soil deposit and the nonlinear characteristics of partial layers, which are assumed to be the cubically nonlinear continuous media. The target problem relates to a nonlinear boundary value problem, the solution of which is carried out using a semi-analytical approach. According to the approach, the problem’s solution is sought using the method of separation of variables, while the solution to the corresponding spectral problem is derived in the form of a power series. Additionally, good agreement is shown between theoretical studies and numerical simulations. The developed approach allows one to evaluate the amplification factor for a nonlinear two-layered soil deposit and to detect changes in the shape of amplification factor profiles when the frequency of an incident wave on a rigid bedrock is varied.

Measurements of Sensitivity and Figure of Merit for Noble Metals (Au, Ag, Cu) Thin Film Biosensor Based on SPR Simulation Characterizations

In this paper, we investigate the influence of varying the thickness of noble metals, namely gold (Au), silver (Ag) and copper (Cu), and the incident light wavelength on the surface plasmon resonance (SPR) properties for biosensor applications. Our analysis employs the Fresnel equations to examine the absorption characteristics of these metals when the refractive index shifts by (0.03,0.06). We explore metal layer thicknesses ranging from [Formula: see text][Formula: see text]nm and incident light wavelengths of [Formula: see text] and 600[Formula: see text]nm, with incident angles ([Formula: see text]) ranging from 0∘ to 90∘. Utilizing simulation analysis in MATLAB, we simulate the SPR responses of these metals when deposited on BK-7 glass prisms, with air as the surrounding medium. Our calculations reveal the absorption properties of Au, Ag and Cu, as indicated by the angle of incidence ([Formula: see text]SPR). Our findings demonstrate that the highest absorption occurs with copper (Cu) at [Formula: see text] (a.u.) for [Formula: see text][Formula: see text]nm and [Formula: see text][Formula: see text]nm. When [Formula: see text] is adjusted to 600[Formula: see text]nm, gold (Au) exhibits the highest absorption (A) at 0.997 (a.u.) with a thickness of [Formula: see text][Formula: see text]nm. Additionally, we calculate sensitivity values for all three metals, with copper (Cu) yielding the highest sensitivity of 101.6 Reflected Index Units (RIU-1) for both [Formula: see text] and 600[Formula: see text]nm. Furthermore, we compute the Figure Of Merit (FOM), with silver (Ag) achieving the highest FOM of 443 at [Formula: see text][Formula: see text]nm and 451 at [Formula: see text][Formula: see text]nm. These results provide important signs about noble metals’ SPR properties in biosensing, and serve as guides for optimizing the biosensors.

Probing the role of photon strength function models in determining the properties of the hot giant dipole resonance

Probing the role of photon strength function models in determining the properties of the hot giant dipole resonance

The role of the Terminal Benzene Derivatives in Triphenylamine‐Based Oxime Esters for Free Radical Photopolymerization

AbstractIn this study, we investigate the effect of terminal benzene derivatives in triphenylamine‐based oxime esters on their photoreactivity. Five novel oxime esters (Miko series) that containing different benzene derivatives as terminal groups, were synthesized. The electronic properties of the substituents on the benzene ring range from electron‐donating to electron‐withdrawing. Specifically, a methoxy benzene for Miko‐MOB, tert‐butyl benezene for Miko‐t‐Bu, chloro benzene for Miko‐CB, trifluoromethyl benzene for Miko‐TFM, and nitro benzene for Miko‐NB. Additionally, a compound with benzene only as the terminal substituent (TP‐1) was selected for comparision. All the new compounds exhibited higher molar extinction coefficients than TP‐1. Additionally, the steady‐state photolysis and electron spin resonance (ESR) properties would decrease from the electron‐donating substitutes to electron‐withdrawing substitutes. Finally, these oxime esters are utilized in Type I photoinitiating systems for the free radical polymerization of trimethylolpropane triacrylate (TMPTA) under UV or LED@405 nm light irradiation conditions. Among all formulations, Miko‐MOB demonstrated the highest double bond conversion efficiency under both UV and LED@405 nm light irradiation. Thus, terminal benzene derivatives in oxime esters play an important role in tuning the optical and photochemical reaction performance, offering significant value for the design strategy of such photoinitiators.

New Branched Iron(III) Complexes in Fluorescent Environment Created by Carbazole Moieties: Synthesis and Structure, Static Magnetic and Resonance Properties

The branched complexes of Schiff bases with various iron(III) salts, named G2-[L2Fe]+A− (A− is NO3−, Cl−, PF6−), were synthesized using the condensation reaction between carbazole derivatives of salicylic aldehyde and N’-ethylethylenediamine and characterized by various spectroscopic methods (GPC, IR, 1H NMR, UV/Vis). The studies revealed that the coordination of the two ligand molecules to metal occurs through the nitrogen ions and oxygen atom of azomethine to form a homoleptic system. All the synthesized coordination compounds were examined for their thermal, optical, and magnetic features. Static magnetic measurements showed that only G2-[L2Fe]Cl was in a single-phase HS state, whereas the Fe(III) ions of G2-[L2Fe]NO3 and G2-[L2Fe]PF6 at room temperatures were in mixed low-spin (LS, S = 1/2) and high-spin (HS, S = 5/2) states: 58.9% LS/41.1% HS for G2-[L2Fe]NO3, 56.1% LS and 43.9% HS for G2-[L2Fe]PF6. All G2-[L2Fe]+A− complexes demonstrate antiferromagnetic exchange interactions between neighboring Fe(III) ions. The ground spin state at 2.0 K revealed a Brillouin contribution from non-interacting LS ions and a proportion of the HS Fe(III) ions not participating in AFM interactions: 57%, 18%, and 16% for G2-[L2Fe]Cl, G2-[L2Fe]NO3 and G2-[L2Fe]PF6, respectively. EPR measurements confirmed the presence of magnetically active HS and LS states of Fe(III) ions and made it possible to distinguish two HS types-with strong low-symmetry (I-type) and weak, distorted octahedral environments (II-type). It was shown that G2-[L2Fe]+A− complexes are magnetically inhomogeneous and consist of two magnetic sub-lattices: AFM-correlated chains in layers from the I-type HS Fe(III) centers and dynamic short-range AFM ordered LS/II-type HS Fe(III) centers in the paramagnetic phase located between the layers.

Customized Self-Assembled Gold Nanoparticle-DNA Origami Composite Templates for Shape-Directed Growth of Plasmonic Structures.

The metal plasmonic nanostructure has the optical property of plasmon resonance, which holds great potential for development in nanophotonics, bioelectronics, and molecular detection. However, developing a general and straightforward method to prepare metal plasmonic nanostructures with a controllable size and morphology still poses a challenge. Herein, we proposed a synthesis strategy that utilized a customizable self-assembly template for shape-directed growth of metal structures. We employed gold nanoparticles (AuNPs) as connectors and DNA nanotubes as branches, customizing gold nanoparticle-DNA origami composite nanostructures with different branches by adjusting the assembly ratio between the connectors and branches. Subsequently, various morphologies of plasmonic metal nanostructures were created using this template shape guided strategy, which exhibited enhancement of surface-enhanced Raman scattering (SERS) signals. This strategy provides a new approach for synthesizing metallic nanostructures with multiple morphologies and opens up another possibility for the development of customizable metallic plasmonic structures with broader applications.