Showing papers on "Scattering published in 2022"
TL;DR: In this paper, the Ni@Co/C@polypyrrole (PPy) composites integrating the advantages of component and microstructure were fabricated, which effectively optimized the impedance matching and improved the EM attenuation.
109 citations
TL;DR: In this paper , the Ni@Co/C@polypyrrole (PPy) composites integrating the advantages of component and microstructure were fabricated, and the addition of Co/C and PPy effectively optimized the impedance matching and improved the EM attenuation.
104 citations
TL;DR: In this article , the authors proposed a method for the optimization of thermoelectric properties by introducing strong grain boundary scattering of low-frequency phonons in bulk nanostructures.
Abstract: Bulk nanostructuring has been one of the leading strategies employed in the past decade for the optimization of thermoelectric properties by introducing strong grain boundary scattering of low-frequency phonons. However,...
82 citations
TL;DR: The FourPhonon package as mentioned in this paper is a computational package that can calculate four-phonon scattering rates in crystals using the Boltzmann transport equation (BTE) solver.
75 citations
TL;DR: The FourPhonon package as discussed by the authors is a computational package that can calculate four-phonon scattering rates in crystals using the Boltzmann transport equation (BTE) solver.
73 citations
TL;DR: In this article, a high-density 2D Ni2P nanosheets were grown vertically and cross-linked on the surface of 1D silk-derived carbon fiber.
63 citations
TL;DR: In this paper , NiCo2O4/C composites are synthesized via a hydrothermal route, whose absorption properties are investigated by different morphologies regulated by changing calcination temperature.
53 citations
TL;DR: In this article , the authors successfully prepared biomass-derived borocarbonitride (BCN) nanosheets with excellent electromagnetic wave absorption and thermal management properties by a general, green and economical strategy using biomass coconut shell as carbon source, and explored the effect of the coconut shell charcoal content on its performance.
50 citations
24 Mar 2022
TL;DR: In this paper , a series of review articles on scattering amplitudes in gauge theory, gravity, and superstring theory is presented, from basic aspects to a selection of current research and developments.
Abstract: This is an introduction to, and invitation to read, a series of review articles on scattering amplitudes in gauge theory, gravity, and superstring theory. Our aim is to provide an overview of the field, from basic aspects to a selection of current (2022) research and developments.
49 citations
TL;DR: In this article , the authors derived the height measurement signal model for flat ground reflection combined with the two diversity techniques and modified it to make it suitable for the classical super-resolution height measurement algorithms, including the generalized multiple signal classification(MUSIC) algorithm and steering vector synthesis (SVS) MUSIC algorithm.
42 citations
24 Mar 2022
TL;DR: In this article , the double copy of three-point amplitudes has been studied in the context of gravity and general relativity, and it has been shown that it can extend elegantly to exact solutions.
Abstract: Scattering amplitudes have their origin in quantum field theory, but have wide-ranging applications extending to classical physics. We review a formalism to connect certain classical observables to scattering amplitudes. An advantage of this formalism is that it enables us to study implications of the double copy in classical gravity. We discuss examples of observables including the total change of a particle’s momentum, and the gravitational waveform, during a scattering encounter. The double copy also allows direct access to classical solutions in gravity. We review this classical double copy starting from its linearised level, where it originates in the double copy of three-point amplitudes. The classical double copy extends elegantly to exact solutions, making a connection between scattering amplitudes and the geometric formulation of general relativity.
TL;DR: In this article, a CoS2/Cu2S embedded N/S co-doped mesh-like carbonaceous composites with enhanced electromagnetic wave absorbing performance was successfully prepared using carboxymethyl cellulose hydrogel spheres as starting materials by freeze-drying and high-temperature carbonization.
TL;DR: Feng et al. as mentioned in this paper measured the polarization of five repeating fast radio bursts and found that each source is polarized at high frequencies but becomes depolarized below a threshold frequency that varies between sources.
Abstract: The polarization of fast radio bursts (FRBs), which are bright astronomical transient phenomena, contains information about their environments. Using wide-band observations with two telescopes, we report polarization measurements of five repeating FRBs and find a trend of lower polarization at lower frequencies. This behavior is modeled as multipath scattering, characterized by a single parameter, σRM, the rotation measure (RM) scatter. Sources with higher σRM have higher RM magnitude and scattering time scales. The two sources with the highest σRM, FRB 20121102A and FRB 20190520B, are associated with compact persistent radio sources. These properties indicate a complex environment near the repeating FRBs, such as a supernova remnant or a pulsar wind nebula, consistent with their having arisen from young stellar populations. Description Polarized repeating fast radio bursts Fast radio bursts (FRBs) are intense, millisecond flashes of radio emission from extragalactic sources of unknown origin. Most FRBs are seen only once, but others repeat at irregular intervals and thereforre can be followed. Feng et al. measured the polarization of five repeating FRBs (see the Perspective by Caleb). They found that each source is polarized at high frequencies but becomes depolarized below a threshold frequency that varies between sources. The authors found that all repeating FRBs are 100% polarized at the source, before the radio waves scatter off complex foreground structures such as supernova remnants. These results constrain theories of the repeating FRB emission mechanism. —KTS Repeating fast radio bursts are polarized at high radio frequencies, whereas low frequencies are depolarized by scattering.
TL;DR: In this article , the authors proposed two estimation methods with different measurement models for the underdetermined case, i.e., the number of scattering waves from ships is larger than number of sensors, which can cure the problem of existing method is poor under low interference signal ratio.
Abstract: Ship target detection using radar is an important application in military and civilian fields. For the polarization estimation of scattering waves in the underdetermined case, i.e., the number of scattering waves from ships is larger than the number of sensors, this paper proposes two estimation methods with different measurement models. 1) For the single-vector-sensor model, this paper proposes the polarization-invariant ESPRIT-based method. This method can estimate the polarization of signals containing target echo, interference, and noise, which can cure the problem that the accuracy of existing method is poor under low interference signal ratio. 2) For the multi-vector-sensor model, this paper proposes an improved ESPRIT method based on the spatial-invariant and time-invariant simultaneously, which can increase the degree of freedom without increasing hardware cost. As for another problem of multi-vector-sensor, i.e., almost all existing methods assume that the number of scattering waves is known, this paper introduces the polarization spectrum for the first time, which can estimate the polarization parameters when the number of scattering waves is unknown. Finally, we analyze the two proposed ESPRIT-based methods comparing with some existing methods through Monte Carlo simulation, which results demonstrate the efficience of the proposed methods.
TL;DR: In this article , the scaling laws among the superconducting transition temperature (Tc), the linear-in-T scattering coefficient (A1), and the doping level (x) in electron-doped copper oxide La2-xCexCuO4 were investigated.
Abstract: Marked evolution of properties with minute changes in the doping level is a hallmark of the complex chemistry that governs copper oxide superconductivity as manifested in the celebrated superconducting domes and quantum criticality taking place at precise compositions1-4. The strange-metal state, in which the resistivity varies linearly with temperature, has emerged as a central feature in the normal state of copper oxide superconductors5-9. The ubiquity of this behaviour signals an intimate link between the scattering mechanism and superconductivity10-12. However, a clear quantitative picture of the correlation has been lacking. Here we report the observation of precise quantitative scaling laws among the superconducting transition temperature (Tc), the linear-in-T scattering coefficient (A1) and the doping level (x) in electron-doped copper oxide La2-xCexCuO4 (LCCO). High-resolution characterization of epitaxial composition-spread films, which encompass the entire overdoped range of LCCO, has enabled us to systematically map its structural and transport properties with unprecedented accuracy and with increments of Δx = 0.0015. We have uncovered the relations Tc ~ (xc - x)0.5 ~ (A1□)0.5, where xc is the critical doping in which superconductivity disappears and A1□ is the coefficient of the linear resistivity per CuO2 plane. The striking similarity of the Tc versus A1□ relation among copper oxides, iron-based and organic superconductors may be an indication of a common mechanism of the strange-metal behaviour and unconventional superconductivity in these systems.
TL;DR: A ternary layered ceramic of Y3Si2C2 was successfully in-situ synthesized on the surface of home-made third-generation KD-SA SiC fiber for the first time by molten salt method aimed at improving the electromagnetic wave (EMW) absorption as discussed by the authors.
TL;DR: In this paper , the eikonal exponentiation of the amplitude in impact-parameter space when spinning particles are involved in the scattering was investigated and it was shown that the leading Eikonal exhibits exponentiation up to O ð G 2 Þ in the limit where the spacetime dimension D → 4 .
Abstract: We initiate a study into the eikonal exponentiation of the amplitude in impact-parameter space when spinning particles are involved in the scattering. Considering the gravitational scattering of two spin- 1 = 2 particles, we demonstrate that the leading eikonal exhibits exponentiation up to O ð G 2 Þ in the limit where the spacetime dimension D → 4 . We find this to hold for general spin orientations. The exponentiation of the leading eikonal including spin is understood through the unitarity properties at leading order in ℏ of momentum-space amplitudes, allowing the extension of our arguments to arbitrary-spin scattering.
TL;DR: In this paper , a method that takes into account light scattering in the resin prior to computing projection patterns is proposed, and it is experimentally demonstrated that implementation of this correction is critical when printing objects whose size exceeds the scattering mean free path.
Abstract: 3D printing has revolutionized the manufacturing of volumetric components and structures in many areas. Several fully volumetric light‐based techniques have been recently developed thanks to the advent of photocurable resins, promising to reach unprecedented short print time (down to a few tens of seconds) while keeping a good resolution (around 100 μm). However, these new approaches only work with homogeneous and relatively transparent resins so that the light patterns used for photo‐polymerization are not scrambled along their propagation. Herein, a method that takes into account light scattering in the resin prior to computing projection patterns is proposed. Using a tomographic volumetric printer, it is experimentally demonstrated that implementation of this correction is critical when printing objects whose size exceeds the scattering mean free path. To show the broad applicability of the technique, functional objects of high print fidelity are fabricated in hard organic scattering acrylates and soft cell‐laden hydrogels (at 4 million cells mL−1). This opens up promising perspectives in printing inside turbid materials with particular interesting applications for bioprinting cell‐laden constructs.
TL;DR: In this paper , a review of spin-flip emitters is presented, with a brief introduction to ligand field theory as a framework to understand this phenomenon and outline prerequisites for efficient spin-FLIP emission including ligand fields strength, symmetry, intersystem crossing and common deactivation pathways.
Abstract: In molecular photochemistry, charge-transfer emission is well understood and widely exploited. In contrast, luminescent metal-centered transitions only came into focus in recent years. This gave rise to strongly phosphorescent CrIII complexes with a d3 electronic configuration featuring luminescent metal-centered excited states which are characterized by the flip of a single spin. These so-called spin-flip emitters possess unique properties and require different design strategies than traditional charge-transfer phosphors. In this review, we give a brief introduction to ligand field theory as a framework to understand this phenomenon and outline prerequisites for efficient spin-flip emission including ligand field strength, symmetry, intersystem crossing and common deactivation pathways using CrIII complexes as instructive examples. The recent progress and associated challenges of tuning the energies of emissive excited states and of emerging applications of the unique photophysical properties of spin-flip emitters are discussed. Finally, we summarize the current state-of-the-art and challenges of spin-flip emitters beyond CrIII with d2, d3, d4 and d8 electronic configuration, where we mainly cover pseudooctahedral molecular complexes of V, Mo, W, Mn, Re and Ni, and highlight possible future research opportunities.
TL;DR: In this paper , toy models for collective neutrino oscillations induced by neutrinos self-interactions are investigated, with special emphasis on inhomogeneous systems with densities following a profile.
Abstract: We investigate toy models for spatial and temporal instabilities in collective neutrino oscillations induced by neutrino self-interactions, with special emphasis on inhomogeneous systems with densities following a profile. Simulations are based on a mathematica program that solves the Liouville equation with or without vacuum terms, refractive terms from a background medium, and neutrino-neutrino forward scattering, in one space dimension and in time. A discrete number of momentum modes are characterized by the neutrino velocity projection on the spatial direction. We also consider the effects of charged current interaction source terms and neutral current scattering contributions. We find that refractive effects from the medium, in particular for density distributions with a profile, and neutral current non-forward scattering off the background medium can strongly influence fast collective flavor transformations. Specifically we find that if both are present, fast flavor conversions can be strongly suppressed or at least delayed.
TL;DR: In this article , a new indirect boundary integral equation method (IBIEM) is developed to solve the seismic wave scattering problem in a three-dimensional fluid-saturated layered half-space.
Abstract: A new indirect boundary integral equation method (IBIEM) is developed to solve the seismic wave scattering problem in a three-dimensional fluid-saturated layered half-space. Based on Biot's theory, the Green's functions of inclined circular loads in porous elastic layered half-space are firstly deduced. According to the single-layer potential theory, when establishing the scattered wave field, the uniform surface loads and fluid sources are located directly on the boundary surfaces of the scatterers, so as to avoid determining the optimal location of fictitious wave sources surface. At the same time, the radiation condition of wave in semi-infinite layered media can be accurately realized by using the dynamic Green's function of concentrated load, and the computational memory can be greatly reduced. The scattering of seismic waves by a canyon topography in saturated layered half-space is examined in detail. The numerical results indicate that with the increase of the porosity of the overlying soil, the amplitude of surface displacement can be amplified by 1∼6 times, and the amplification effect is more significant near the corner of the canyon, which can be attributed to the superposition of wave diffraction effect and resonance amplification effect of saturated soil layer.
TL;DR: In this paper, a tree blossom Ni/Nitrogen doped Carbon (NC)/ Carbon (C) composites were prepared by in situ pyrolysis under an argon atmosphere.
TL;DR: DarkELF as mentioned in this paper is a python package to calculate interaction rates of light dark matter in dielectric materials, including screening effects, in terms of the energy loss function (ELF) of material.
Abstract: We present DarkELF, a python package to calculate interaction rates of light dark matter in dielectric materials, including screening effects. The full response of the material is parametrized in the terms of the energy loss function (ELF) of material, which DarkELF converts into differential scattering rates for both direct dark matter electron scattering and through the Migdal effect. In addition, DarkELF can calculate the rate to produce phonons from sub-MeV dark matter scattering via the dark photon mediator, as well as the absorption rate for dark matter comprised of dark photons. The package includes precomputed ELFs for Al, ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$, GaAs, GaN, Ge, Si, ${\mathrm{SiO}}_{2}$, and ZnS, and allows the user to easily add their own ELF extractions for arbitrary materials.
TL;DR: In this article , it was shown that 3D Carrollian CFTs living on the null boundary of 4D flat space can potentially compute bulk scattering amplitudes, which is the time-dependent branch that is related to bulk scattering.
Abstract: Recent attempts at the construction of holography for asymptotically flat spacetime have taken two different routes. Celestial holography, involving a two dimensional (2D) conformal field theory (CFT) dual to 4D Minkowski spacetime, has generated novel results in asymptotic symmetry and scattering amplitudes. A different formulation, using Carrollian CFTs, has been principally used to provide some evidence for flat holography in lower dimensions. Understanding of flat space scattering has been lacking in the Carroll framework. In this Letter, using ideas from Celestial holography, we show that 3D Carrollian CFTs living on the null boundary of 4D flat space can potentially compute bulk scattering amplitudes. Three-dimensional Carrollian conformal correlators have two different branches, one depending on the null time direction and one independent of it. We propose that it is the time-dependent branch that is related to bulk scattering. We construct an explicit field theoretic example of a free massless Carrollian scalar that realizes some desired properties.
TL;DR: In this paper , the authors show that in n-type-doped magneto-optic InAs with a static magnetic field where light coupling is mediated by a guided-mode resonator structure, their resonant frequency coincides with the epsilon-near-zero resonance of the doped indium arsenide.
Abstract: Nonreciprocal elements are a vital building block of electrical and optical systems. In the infrared regime, there is a particular interest in structures that break reciprocity because their thermal absorptive (and emissive) properties should not obey the Kirchhoff thermal radiation law. In this work, we break time-reversal symmetry and reciprocity in n-type–doped magneto-optic InAs with a static magnetic field where light coupling is mediated by a guided-mode resonator structure, whose resonant frequency coincides with the epsilon-near-zero resonance of the doped indium arsenide. Using this structure, we observe the nonreciprocal absorptive behavior as a function of magnetic field and scattering angle in the infrared. Accounting for resonant and nonresonant optical scattering, we reliably model experimental results that break reciprocal absorption relations in the infrared. The ability to design these nonreciprocal absorbers opens an avenue to explore devices with unequal absorptivity and emissivity in specific channels.
14 Mar 2022
TL;DR: Coherent elastic neutrino-nucleus scattering (CEνNS) is a process in which neutrinos scatter on a nucleus which acts as a single particle as discussed by the authors .
Abstract: Coherent elastic neutrino-nucleus scattering (CEνNS) is a process in which neutrinos scatter on a nucleus which acts as a single particle. Though the total cross section is large by neutrino standards, CEνNS has long proven difficult to detect, since the deposited energy into the nucleus is ∼ keV. In 2017, the COHERENT collaboration announced the detection of CEνNS using a stopped-pion source with CsI detectors, followed up the detection of CEνNS using an Ar target. The detection of CEνNS has spawned a flurry of activities in high-energy physics, inspiring new constraints on beyond the Standard Model (BSM) physics, and new experimental methods. The CEνNS process has important implications for not only high-energy physics, but also astrophysics, nuclear physics, and beyond. This whitepaper discusses the scientific importance of CEνNS, highlighting how present experiments such as COHERENT are informing theory, and also how future experiments will provide a wealth of information across the aforementioned fields of physics.
TL;DR: In this paper , a serious of Co/Ni NPs decorated porous carbon sphere were successfully prepared via a combined method of activation, hydrothermal and annealing process, by controlling the addition amount of activator and the concentration of precursor, the appropriate morphology and impedance matching can be obtained in the as-prepared hybrid.
TL;DR: In this article , the authors summarize the amazing power and fundamental limits of controlling multiple light scattering, which lay the physical foundation to harness multiply-scattered light for imaging and communication purposes.
Abstract: The main obstacle for optical imaging or for sending information through turbid media such as paint, clouds and biological tissue is the random scattering of light. Owing to its immense complexity, the process of multiple scattering has long been described by the diffusion equation, which ignores the interference of scattered light. Recent developments in optical wavefront shaping and phase recording techniques have enabled the breaking of the diffusion limit and the control of coherent light transport in complex media, including strongly scattering tissues and multimode optical fibres with random mode mixing. Great advances have been made in focusing and controlling the transmission of light through such complex systems and in performing various tasks behind them, such as optical micro-manipulation. Here, we summarize the amazing power and the fundamental limits of controlling multiple light scattering, which lay the physical foundation to harness multiply-scattered light for imaging and communication purposes. Connections to practical applications are illustrated, in particular in those areas covered in the companion articles in this issue. Multiple scattering fundamentally complicates the task of sending light through turbid media, as many applications require. This Review summarizes the theoretical framework and experimental techniques to understand and control these processes.
TL;DR: In this paper , the authors combine the organic cation control engineering with temperature-dependent transient absorption spectroscopy to systematically study the interband exciton relaxation pathways in layered A2SnI4 (A = PEA+, BA+, HA+, and OA+) structures.
Abstract: Two-dimensional (2D) Sn-based perovskites are a kind of non-toxic environment-friendly luminescent material. However, the research on the luminescence mechanism of this type of perovskite is still very controversial, which greatly limits the further improvement and application of the luminescence performance. At present, the focus of controversy is defects and phonon scattering rates. In this work, we combine the organic cation control engineering with temperature-dependent transient absorption spectroscopy to systematically study the interband exciton relaxation pathways in layered A2SnI4 (A = PEA+, BA+, HA+, and OA+) structures. It is revealed that exciton-phonon scattering and exciton-defect scattering have different effects on exciton relaxation. Our study further confirms that the deformation potential scattering by charged defects, not by the non-polar optical phonons, dominates the excitons interband relaxation, which is largely different from the Pb-based perovskites. These results enhance the understanding of the origin of the non-radiative pathway in Sn-based perovskite materials.