Quadrupole Resonance Research Articles

Giant Quadrupole Resonances within neutron-induced α-particle emission?

The particular conditions for the recent measurement of 91Zr(n,α)88Sr reaction cross sections at incident energies below 5.3 MeV [Phys. Rev. C 106, 064602 (2022)] as well as a previous detailed analysis of other reaction channels involving neutrons incident on 91Zr, using a consistent set of model parameters, have two main advantages. First, the close agreement between the calculated and experimentally obtained data for the incident energy associated mainly with the ground-state activation provides strong support for the α-particle optical potential involved in this analysis. Second, a further underestimation of the cross section is observed around the energy corresponding to the isoscalar giant quadrupole resonance (ISGQR), beyond any model parameter uncertainty. This underestimation is consistent with previous observations of ISGQR-like α-particle decay of excited nuclei for neutron-induced reactions in the mass range 54≤A≤98. To phenomenologically identify the ISGQR-like behavior, a comparison is made between their strengths and the ISGQR strengths measured through the (γ,α) reaction and inelastic scattering of 3He and α-particles. Additionally, an isotope effect, possibly related to the decrease in Q-value with the target-nuclei asymmetry parameter, supports the observation of a low energy-weighted sum rule (EWSR) fraction for the ISGQR-like strength function in the excited nucleus 92Zr.

Magnetic quadrupolar resonance in a symmetric three-layered plasmonic metasurface

Dark plasmon mode with even symmetry presents an effective way for manipulating light-matter interactions due to its attractive properties of small radiative loss and strongly intensified near-field, which opens up space for both fundamental explorations and optoelectronic device developments. In this paper, we demonstrate magnetic quadrupolar resonance in a symmetric plasmonic metasurface under oblique light incidence. In a three-layered metasurface made of a cross-shaped gold array on top of a magnesium fluoride film backed with a copper ground plane, a magnetic quadrupolar resonance is excited at 37.3 THz with a quality factor of 34, which is four times of the regular magnetic dipolar resonance excited in the same structure. By increasing the incident angle, asymmetry perturbation on the magnetic quadrupolar mode becomes more pronounced as evidenced from its decreased quality factor. In addition, due to the structure symmetry of the used metal cross, the metasurface exhibits polarization-selective excitation of two separate magnetic quadrupolar modes at 37.3 THz and 42.3 THz for the electric field along four symmetry axes of the structure. Our demonstrated distinctive magnetic quadrupolar resonance offers an alternative mode design in plasmonic metamaterials with an improved quality factor, which could be beneficial for metamaterial applications in sensing, optical filtering and infrared emission manipulation etc.

Enhanced light confinement in nonlocal resonant metasurfaces with weak multipolar scatterers

Stronger light confinement can be enabled by nanoantennas in the nanostructure and result in efficient control of the directionality of the scattering. We report on an observation of the well-pronounced multipolar resonances from nickel nanoantennas originating from collective effects. We show that the collective coupling of multipolar modes from weak scatterers can substantially enhance the electric dipole and quadrupole resonances. We also demonstrate the generalized lattice Kerker effect in this nanoantenna array. Resonant multipolar excitations within nickel nanoantenna arrays can significantly enhance phenomena such as magneto-optical effects, indicating promising potential for advanced applications in the field of nanophotonics and sensing.

Polarization-independent tetramer metastructure with multi-Fano resonances governed by quasi-bound states in the continuum

We propose what we believe to be a novel metastructure consisting of silicon nanoblock tetramer clusters and investigated theoretically and experimentally how to enhance surface sensing capabilities with polarization-independent properties through bound states in the continuum (BICs). By introducing square defects, three quasi-BIC modes are excited at the wavelengths of 1013.29 nm, 1109.57 nm, and 1310.73 nm with a modulation depth up to 100% and a Q-factor of 16618, while achieving a sensitivity of 256 nm/RIU and a figure of merit of 2519.7 RIU−1. Utilizing the finite-difference method in the time domain (FDTD), we have analyzed the electromagnetic near-field distributions, polarization properties, and robustness corresponding to resonance dips at different wavelengths. Our results reveal that the distinct electromagnetic near-field distributions excited by the quasi-BIC modes are characterized by the strong field confinement within the silica nanoblock tetramer clusters. The modes are primarily governed by magnetic quadrupole (MQ) resonance and toroidal dipole (TD) moment. Additionally, the polarization-independent properties of the metastructure are demonstrated to ensure that they can effectively respond to the incident light regardless of its polarization state, while the robustness is investigated to show the stability and reliability by shifting square defects. Moreover, the transmission spectra of the metastructure is experimentally verified by immersing the sample into CaCl2 solutions in different concentrations. This work plays a pivotal role in creating further novel and high-performance optical metastructures while demonstrating the potential applications of quasi-BIC modes in precision sensing in the future.

(Invited) Mie Resonant Silicon Nanospheres for Scattering-Fluorescence Dual-Mode Imaging, Medical Diagnosis and Photothermal Therapy

In recent years, a variety of multimodal and multifunctional nanoparticles have been developed for biomedical applications such as cellular imaging, biomolecule detection, and medical diagnosis and treatment. A common platform of multifunction nanoparticles is metallic ones with localized surface plasmon resonances. A drawback of metallic nanoparticles for biomedical applications is the Ohmic loss that leads to fluorescence quenching of attached molecules and local heating under light irradiation. We have been developing metal-free nanoprobes capable of scattering/fluorescence dual-mode imaging, medical diagnosis and photothermal therapy. The nanoprobes are composed of a silicon nanosphere core having Mie resonances in the visible to near infrared range and a fluorophore-doped silica shell [1, 2]. In this presentation, we first show scattering properties of the Mie resonant Si nanospheres. We then discuss the dark-field scattering and photoluminescence images/spectra of the core-shell nanoparticles and demonstrate that the fluorescence spectra are strongly modified by the Mie modes of a silicon nanosphere core by the Purcell effect. We demonstrate in the in vitro imaging of human cancer cells that the developed core-shell nanoparticles work as scattering/fluorescence dual-mode imaging nanoprobes.We then add the capability of glutathione sensing to the core-shell nanoprobes. It is known that the glutathione level tends to be elevated in some kinds of cancers and thus it can be used as a biomarker. To add the capability of glutathione sensing, we cover the surface of the core-shell nanoprobes with manganese oxide (MnO2). MnO2 quenches the fluorescence of the core-shell nanoparticles, and it is recovered if the MnO2 shell is resolved by the reaction with glutathione. Therefore, we can monitor the glutathione level by the fluorescence intensity. The advantage of the dual-mode imaging is that the glutathione level can be monitored by the fluorescence intensity, while the particle position is always monitored by the scattering image.Finally, we discuss the capability of Si nanospheres for photothermal therapy. We show that Si nanospheres exhibit efficient light absorption at the wavelengths of magnetic type Mie resonances such as magnetic dipole (MD) and magnetic quadrupole (MQ) resonances, and can be heated up very easily by light irradiation. An advantage of Si nanospheres compared to plasmonic nanoparticles as a light absorber for photothermal therapy is the much narrower resonances. Because of the narrow resonance, we can easily switch heating and non-heating modes. This means that if we want to heat up a nanoparticle, we can choose a specific wavelength that corresponds to e.g., the MQ mode, while if we want to excite fluorophores without heating, we can choose off-resonance wavelength for the excitation. Another advantage of Si nanospheres is the capability to monitor the temperature by Raman scattering. We show the relation between the temperature, wavelength and the size of silicon nanospheres and discuss the Mie modes suitable for the photothermal therapy application.

Effect of Dynamical Motion in ab Initio Calculations of Solid-State Nuclear Magnetic and Nuclear Quadrupole Resonance Spectra.

Solid-state nuclear magnetic resonance (SSNMR) and nuclear quadrupole resonance (NQR) spectra provide detailed information about the electronic and atomic structure of solids. Modern ab initio methods such as density functional theory (DFT) can be used to calculate NMR and NQR spectra from first-principles, providing a meaningful avenue to connect theory and experiment. Prediction of SSNMR and NQR spectra from DFT relies on accurate calculation of the electric field gradient (EFG) tensor associated with the potential of electrons at the nuclear centers. While static calculations of EFGs are commonly seen in the literature, the effects of dynamical motion of atoms in molecules and solids have been less explored. In this study, we develop a method to calculate EFGs of solids while taking into account the dynamics of atoms through DFT-based molecular dynamics simulations. The method we develop is general, in the sense that it can be applied to any material at any desired temperature and pressure. Here, we focus on application of the method to NaNO2 and study in detail the EFGs of 14N, 17O, and 23Na. We find in the cases of 14N and 17O that the dynamical motion of the atoms can be used to calculate mean EFGs that are in closer agreement with experiments than those of static calculations. For 23Na, we find a complex behavior of the EFGs when atomic motion is incorporated that is not at all captured in static calculations. In particular, we find a distribution of EFGs that is influenced strongly by the local (changing) bond environment, with a pattern that reflects the coordination structure of 23Na. We expect the methodology developed here to provide a path forward for understanding materials in which static EFG calculations do not align with experiments.

Effect of ground-state deformation on the isoscalar giant monopole resonance and the first observation of overtones of the isoscalar giant quadrupole resonance in rare-Earth Nd isotopes

The strength distributions of the Isoscalar Giant Monopole Resonance (ISGMR) and Isoscalar Giant Quadrupole Resonance (ISGQR) in 142,146−150Nd have been determined via inelastic α-particle scattering with the Grand Raiden (GR) Spectrometer at the Research Center for Nuclear Physics (RCNP), Japan. In the deformed nuclei 146−150Nd, the ISGMR strength distributions exhibit a splitting into two components, while the nearly spherical nucleus 142Nd displays a single peak in the ISGMR strength distribution. A noteworthy achievement in this study is the first-time detection of overtones in the Isoscalar Giant Quadrupole Resonance (ISGQR) strength distributions within Nd isotopes at an excitation energy around 25 MeV obtained through Multipole Decomposition Analysis (MDA).

Spin-flip-induced quadrupole resonance in odd- A exotic atoms

We examine the possible existence of quadrupole resonances in exotic atoms containing odd-A nuclei. We find that the spin flip of the deexciting exotic particle can induce a resonance, altering the orbital angular momentum of the nucleus by one quantum. This process results in an excited nucleus with a suppression in x-ray photon emissions during the exotic atom cascade. We provide specific cases of antiprotonic atoms of stable elements where this resonance effect is expected to occur. The study of this phenomena may provide insight into the strong interaction of deeply bound antiprotonic states in the proximity of the unpaired nucleon, and serve as a tool for probing short-lived excited nuclear states. Published by the American Physical Society 2024

Ab initio description of monopole resonances in light- and medium-mass nuclei

Giant resonances (GRs) are a striking manifestation of collective motions in atomic nuclei. The present paper is the second in a series of four dedicated to the use of the projected generator coordinate method (PGCM) for the ab initio determination of the isoscalar giant monopole resonance (GMR) in closed- and open-shell mid-mass nuclei. While the first paper was dedicated to quantifying various uncertainty sources, the present paper focuses on the first applications to three doubly-open shell nuclei, namely 46Ti\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{46}\\hbox {Ti}$$\\end{document}, 28Si\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{28}\\hbox {Si}$$\\end{document} and 24Mg\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{24}\\hbox {Mg}$$\\end{document}. In particular, the goal is to investigate, starting from chiral effective field theory nuclear interactions, (i) the coupling of the GMR with the giant quadrupole resonance (GQR) in intrinsically-deformed nuclei, (ii) the possible impact of shape coexistence and shape mixing on the GMR, (iii) the GMR based on shape isomers and (iv) the impact of anharmonic effects on the monopole response. The latter is studied by comparing PGCM results to those obtained via the quasi-particle random phase approximation (QRPA), the traditional many-body approach to giant resonances, performed in a consistent setting. Eventually, PGCM results for sd-shell nuclei are in good agreement with experimental data, which is attributed to the capacity of the PGCM to capture the important fragmentation of the monopole response in light, intrinsically-deformed systems. Still, the comparison to data in 28Si\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{28}\\hbox {Si}$$\\end{document} and 24Mg\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{24}\\hbox {Mg}$$\\end{document} illustrates the challenge (and the potential benefit) of extracting unambiguous experimental information.

Optical nuclear electric resonance in LiNa: selective addressing of nuclear spins through pulsed lasers

Optical nuclear electric resonance (ONER), a recently proposed protocol for nuclear spin manipulation in atomic systems via short laser pulses with MHz repetition rate, exploits the coupling between the nuclear quadrupole moment of a suitable atom and the periodic modulations of the electric field gradient generated by an optically stimulated electronic excitation. In this theory paper, we extend the scope of ONER from atomic to molecular systems and show that molecular vibrations do not interfere with our protocol. Exploring the diatomic molecule LiNa as a first benchmark system, our investigation showcases the robustness with respect to molecular vibration, and the ability to address and manipulate each of the two nuclear spins independently, simply by adjusting the repetition rate of a pulsed laser. Our findings suggest that it might be possible to shift complicated spin manipulation tasks required for quantum computing into the time domain by pulse-duration encoded laser signals.

Noncollinear Electric Dipoles in a Polar Chiral Phase of CsSnBr3 Perovskite.

Polar and chiral crystal symmetries confer a variety of potentially useful functionalities upon solids by coupling otherwise noninteracting mechanical, electronic, optical, and magnetic degrees of freedom. We describe two phases of the 3D perovskite, CsSnBr3, which emerge below 85 K due to the formation of Sn(II) lone pairs and their interaction with extant octahedral tilts. Phase II (77 K < T < 85 K, space group P21/m) exhibits ferroaxial order driven by a noncollinear pattern of lone pair-driven distortions within the plane normal to the unique octahedral tilt axis, preserving the inversion symmetry observed at higher temperatures. Phase I (T < 77 K, space group P21) additionally exhibits ferroelectric order due to distortions along the unique tilt axis, breaking both inversion and mirror symmetries. This polar and chiral phase exhibits second harmonic generation from the bulk and pronounced electrostriction and negative thermal expansion along the polar axis (Q22 ≈ 1.1 m4 C-2; αb = -7.8 × 10-5 K-1) through the onset of polarization. The structures of phases I and II were predicted by recursively following harmonic phonon instabilities to generate a tree of candidate structures and subsequently corroborated by synchrotron X-ray powder diffraction and polarized Raman and 81Br nuclear quadrupole resonance spectroscopies. Preliminary attempts to suppress unintentional hole doping to allow for ferroelectric switching are described. Together, the polar symmetry, small band gap, large spin-orbit splitting of Sn 5p orbitals, and predicted strain sensitivity of the symmetry-breaking distortions suggest bulk samples and epitaxial films of CsSnBr3 or its neighboring solid solutions as candidates for bulk Rashba effects.

Heterogeneous micellar solubilization within lyotropic liquid crystals interfaces

The solubilization of sodium diclofenac (Na-DFC) in a glycerol monooleate-based emulsion triggers series of structural changes. Incorporation of Na-DFC, leads to formation of a reverse hexagonal mesophase between 2 and 5 wt% Na-DFC. Between 6 and 9 wt% Na-DFC, the hexagonal symmetry gradually transitions to a disordered lamellar mesophase. These structural shifts impact the system's storage modulus, structuring enthalpy, and structural diffusivity. Despite these transitions, the driving force for Na-DFC release remains consistent, leading to hypothesize that the interfacial structure remains unchanged during Na-DFC release.The nano-structural modifications imposed by the Na-DFC load and release were assessed by small-angle X-ray diffraction (SAXD), spin-probe electron paramagnetic resonance (EPR), and nuclear quadrupole resonance (NQR).The selective solubilization of Na-DFC was demonstrated by SAXD peak fittings, revealing an increase of hexagonally oriented rods at the expense of non-oriented micelles, rather than gradual micellar elongation. Computation of the EPR spectra also showcased the selective solubilization of Na-DFC at an enhanced free energy interface (γ), evidenced by step-wise variations in polarity, microviscosity, and order parameters. Additionally, NQR analysis highlighted a higher anisotropy for sodium compared to deuterium, linking the selective solubilization of Na-DFC to heterogeneous structural transformations. These findings underscore the heterogeneous nature of solubilization-release processes, driven by locally increased micellar free energy. Consequently, the loaded Na-DFC interfaces maintain a constant γ, ensuring a consistent release driving force despite the structural transitions affecting the matrix. The ability to selectively solubilize guest molecules may herald a new era in the utilization of selective molecular interfacial loading.

Magnetic transverse unidirectional scattering and longitudinal displacement sensing in silicon nanodimer

Unidirectional scattering, crucial for manipulating light at the nanoscale, has wide-ranging applications from optical manipulation to sensing. While traditionally achieved through interactions between electric multipoles or between electric and magnetic multipoles, reports on unidirectional scattering driven purely by magnetic multipoles are limited. In this study, we undertake a theoretical exploration of transverse unidirectional scattering induced by magnetic multipoles, employing tightly focused azimuthally polarized beams (APBs) in interaction with a silicon nanodimer comprising two non-concentric nanorings. Through numerical simulations and theoretical analysis, we validate the transverse unidirectional scattering, predominantly governed by magnetic dipolar and quadrupolar resonances. Moreover, the directionality of this unidirectional scattering shows a strong correlation with the longitudinal displacement of the nanodimer within a specific range, showcasing its potential for longitudinal displacement sensing. Our study advances optical scattering control in nanostructures and guides the design of on-chip longitudinal displacement sensors.

Electric Field Gradient in Chiral and Tetrahedral Molecules within High-Order LRESC Formalism.

In this work, we present the electric field gradient (EFG) given by the linear response elimination of the small component (LRESC) scheme up to the 1/c4 order (c is the speed of light in vacuum) in CHFClX (X = Br, I, At) chiral molecules, together with CHF2Br and CH2FX (X = Br, I, At) tetrahedral systems. The former could be good candidates for further parity violation studies, especially when heavy atoms are surrounding. In this context, the LRESC scheme demonstrates effective applicability to large tetrahedral and chiral molecules that incorporate heavy elements, with relativistic effects playing a crucial role. The LRESC results of EFG exhibit an excellent agreement with those calculated at the four-component level, giving differences of only hundredths order in a.u. (atomic units) for the bromine nucleus and less than 0.1 a.u. for the iodine nucleus. Regarding the other nuclei, for the chiral molecules, there is a heavy atom effect on the light atom (HALA) for chlorine and fluorine atoms as the substituent halogen atom becomes heavier. Furthermore, the electronic part of the EFG for the central carbon and the fluorine nuclei presents an important dependence with the environment in the molecules under study. With accurate calculations of the EFG and tabulated nuclear quadrupole moment, the nuclear quadrupole coupling constant is obtained within the LRESC scheme, including for the first time correlation effects on the spin-dependent corrections with this methodology, providing results close to the experimental ones for Cl, Br, and I atoms. At the Hartree-Fock level, the differences are around 6% for Br and I nuclei, and at the density functional theory level with the LDA and PBE0 functionals, the differences are no more than 2%.

The large-range strength-switchable circular dichroism in a mechanically reconfigurable chiral metasurface

The strength-switchable circular dichroism (CD) is crucial in the fields of biological detection, analytical chemistry, etc. In this paper, we achieved large-range strength-switchable CD by mechanically stretching polydimethylsiloxane (PDMS) substrate. With normal incidence, the traditional C4 rotation symmetric 卍-shaped chiral array could exhibit obvious optical activity but near-zero CD. However, we found that the giant CD could be gained by breaking the period symmetry in x- and y-directions in the 卍-shaped array. By mechanically stretching PDMS substrate in x-direction, the magnitude of CD is dynamically switched from 0.99 to 0 at 1314.5 nm. Essentially, the giant CD originates from the circular polarization selective excitations of magnetic dipole and electric quadrupole resonances, which is demonstrated by quantitative multipole decomposition and electric and magnetic field analysis. The giant and large-range strength-switchable CD has great potentials in the next generation optical devices.

A survey of nuclear quadrupole deformation in order to estimate the nuclear MQM and its relative contribution to the atomic EDM

Measurement of a non-zero permanent electric dipole moment (EDM) in fundamental particles, such as in an electron or a neutron, or in nuclei or atoms, can help us gain a handle on the sources of Charge-Parity (CP) violation, both in the Standard Model (SM) and beyond. The nuclear magnetic quadrupole moment (MQM), the central topic of this work, is also CP, P, and T violating. Nucleons and nuclei have a non-zero MQM from sources within the SM, but the nuclear MQM is dramatically enhanced if the nuclei are structurally quadrupole deformed. Multiple sources contribute to an atomic EDM namely: (i) nuclear EDM through its Schiff moment, which is enhanced by nuclear octupole deformation, (ii) CP violating interactions between the electrons and the nuclei, and (iii) the nuclear MQM that contributes to the atomic EDM in atoms with an unpaired valence electron. Our survey of nuclear quadrupole deformation identified 48 isotopes as ideal systems in which to search for a CP violating EDM via their enhanced nuclear MQM. Of these candidates, 223,225\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{223,225}$$\\end{document}Fr, 223\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{223}$$\\end{document}Ra, 223,225,227\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{223,225,227}$$\\end{document}Ac, 229\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{229}$$\\end{document}Th, and 229\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{229}$$\\end{document}Pa also have maximally enhanced nuclear Schiff moment contribution due to their octupole deformation. Laser cooling of the isotopes of Fr and Ra, among a few others, has already been demonstrated, making 223,225\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{223,225}$$\\end{document}Fr and 223\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{223}$$\\end{document}Ra some of the best systems in which to measure an EDM.

Unconventional Transverse Magneto‐Optical Kerr Effect in Cobalt Nanopillar Arrays

AbstractNovel magneto‐optical (MO) properties can be actualized through well‐designed nanostructures, greatly improving the application value of MO effects. As only p‐polarized light can generate transverse magneto‐optical Kerr effect (TMOKE) in traditional MO materials, it is quite challenging and valuable to effectuate TMOKE under s‐polarization incidence at optical frequencies. The constructed nanopillar structures in this work can realize a clear TMOKE under both s‐polarization and p‐polarization incidences, as proved by experiments and simulations. Under s‐polarized incident light with an elevation angle of 45°, electric dipole resonance (EDR) and electric quadrupole resonance (EQR) are excited, resulting in the significant enhancement of TMOKE (five orders of magnitude higher than for the planar Co film). The intensity of s‐polarized TMOKE shows an increase with the enhancing diameter and height of the nanopillar structure. The amplitude of p‐polarized TMOKE is also appreciably increased due to the excitation of surface plasmon polaritons (SPPs) and localized surface plasmons (LSPs). Moreover, the Fe and Ni nanopillars display similar reflectivity and s‐polarized TMOKE behaviors in simulations. The s‐polarized TMOKE is unexpectedly observed in ferromagnetic metals for the first time, which builds up a considerable platform for the development and application of novel MO phenomena.

Vortex photon induced nuclear reaction: Mechanism, model, and application to the studies of giant resonance and astrophysical reaction rate

The vortex photon beam induced nuclear reaction is studied. The interaction formalism of nuclei with vortex photons is developed and incorporated into the statistical reaction model to calculate reaction cross-sections. For 138 nuclei of high nuclear astrophysics and structure interest, the cross-sections of γ-ray emission and neutron production from the decay of the giant resonances (GR) populated by vortex photons, e.g., (γvo,γemit) and (γvo,nprod.), are computed. It is shown that for the (γvo,γemit) and (γvo,nprod.) cross-sections, the GR contribution of an individual L is either enhanced or suppressed depending on the parameters of vortex γ-rays, and the contribution from the GR of a specific L can be identified and deduced. To this end, a novel method to exclusively determine the γ-strength function (γSF) for the GR of a specific L is proposed considering the (γvo,γemit) and (γvo,nprod.) measurements, and the feasibility studies demonstrate that the γSF for the giant quadrupole resonance can be extracted. Furthermore, the astrophysical reaction rates of the vortex photon induced reactions in p-process are investigated. It is indicated that photo-nuclear reactions induced by vortex photons will bring new insights in nuclear physics and astrophysics research.

Complete mode conversion of elastic waves by utilizing hexapole resonances in a double-scatterers structure

In recent years, the emergence of elastic metamaterial has provided new methods to manipulate the polarization of elastic waves, achieving elastic mode conversions. This paper theoretically investigates a complete mode conversion effect, where longitudinal waves are completely converted into transverse waves after being reflected by one layer of metamaterial slab. The slab structure contains a pair of cylinders, and the conversion is attributed to the out-of-phase coupled hexapole resonances of the two cylinders. Unlike the monopole, dipole, and quadrupole resonances, the hexapole resonances induce trivially, nearly constantly, effective parameters. The proposed design does not follow the recent popular “reversely designing parameters” method. The conversion based on the hexapole resonances is relatively broadband and wide-angle, which is beneficial for practical applications such as sound absorption.

Multiple fano resonances based on all-dielectric metastructure for refractive index sensing

We investigate an optical refractive index sensor based on an all-dielectric metastructure in the near-infrared regime for achieving high sensitivity and high quality factor (Q-factor). By introducing the asymmetry in the metastructure, four sharp Fano resonances with high Q-factor are generated owing to the transition from symmetry-protected bound states in the continuum (BIC) to quasi-BIC, and the magnetic quadrupole (MQ) resonance, magnetic dipole (MD) resonance, and toroidal dipole (TD) resonance are analyzed by a combination of the field distributions. By evaluating the sensing performance with finite difference time domain (FDTD), the highest Q-factor can reach 6900, the modulation depth is close to 100 %, the sensitivity can reach 288 nm/RIU, and the figure of merit (FOM) is 888 RIU−1. Furthermore, the sensor is prepared using electron beam lithography (EBL), and inductively coupled plasma reactive ion etch (ICP-RIE), and high sensitivity is achieved in liquids with different refractive indices in the near-infrared. The results show a good sensing performance of the designed metastructure. Our findings will give access to the development of applications in non-linear devices, narrow-band filters, optical switches, and quantum nanophotonics.