Scattering Cross Section Research Articles

Cavity-modulated visualization of dual magnetic coupling behavior for multifunctional Co/DMAOP composites

The demand of microwave-absorbing materials for the marine environment requires the multifunctional characteristic, including microwave absorption, corrosion protection, and antimicrobial. However, achieving these properties without compromising on the microwave-absorbing performance remains a significant challenge. Here, we present a self-sacrificial template strategy to synthesize Co-metal–organic framework (MOF)-74 nanorods, achieving synergistic anticorrosion and antibacterial effects by the introduction of dimethyl octadecyl (3-trimethoxysilylpropyl) ammonium chloride (DMAOP). Our findings show that by adjusting the cavity shape, internal and exterior double-coupling behaviors may occur simultaneously, greatly increasing the synthetic composites’ capacity for magnetic loss. As a result, the Co/DMAOP-120 with 100.00 % cavity structure has an ideal reflection loss (RL) value of up to − 68.05 dB and an effective absorption bandwidth (EAB) of 4.88 GHz at a thickness of 3 mm. This material also shows significant corrosion resistance and a bacterial inhibition rate against Staphylococcus aureus (S. aureus) of 93.89 %. The maximum radar scattering cross section (RCS) of Co/DMAOP-120 under far-field conditions is significantly reduced compared to that of a perfect electrical conductor (PEC), further validating the highly efficient wave-absorbing capability of Co/DMAOP-120 in real-world environments. The new magnetic loss mechanism offers fresh recommendations for designing the microstructure of materials that waves in absorb several ways.

Features in the electron elastic scattering cross sections of atoms Sb, Xe and Bi, Rn

Abstract For atoms having pairwise similar electronic configurations, Sb([Cd]5p3), Xe([Cd]5p6) and Bi([Hg]6p3), Rn([Hg]6p6), features in the energy dependences of integral (ICSs) and differential (DCSs) cross sections of electron elastic scattering are considered theoretically. The positions of the Ramsauer-Townsend minimum (RT) and the low-energy maxima in the ICSs are calculated. The minima in the DCSs have been studied within the collision energy range from 0.1 (Sb, Xe, Bi) and 0.5 (Rn) eV up to 1000 (Sb), 2000 (Xe), 3000 (Bi) and 4000 (Rn) eV. The phase shifts, scattering amplitudes and cross sections have been calculated in the relativistic complex optical potential (OP) approximation. The results of the above OP calculation agree well with the experimental and the theoretical data. The energy dependences of the angular positions of the DCSs minima of these atoms are considered in detail. The energy and the angular positions of 15 (Sb), 17 (Xe and Bi) and 18 (Rn) critical minima (CM) in the DCSs have been found. The highest energy CM are located at: Sb – [727.6 eV; 131.89], Xe – [791.4 eV; 133.16], Bi – [1810.8 eV; 137.34], Rn – [1918.8 eV; 137.64]. A high-angle CM are located at: Sb – [233.6 eV; 151.08], Xe – [256.5 eV; 151.05], Bi – [180.3 eV; 157.30], Rn – [204.0 eV; 155.36].

Electron scattering study on acetic acid and methyl formate

Abstract In this work we report the results of a theoretical calculation of the elastic, differential scattering, and excitation cross-sections on electron interactions with the C2H4O2 isomers (methyl formate and acetic acid) using the ab initio R-matrix method in the energy range of 0.1-20 eV. The computations were performed using static exchange (SE), static exchange plus polarization (SEP) and Close-Coupling (CC) models with electronic structure calculation for these molecules performed using GAMESS. In the electron scattering cross section we have identified π* type resonance in both the isomers. Ionization cross-sections for both the molecules from ionization threshold to 500 eV using BEB method are also presented here. We endeavoured to explore the isomeric effect on various cross sections among these two isomers and included the third isomer, namely glycolaldehyde, as reported in our previous publication.

Superscattering of light: fundamentals and applications.

Superscattering, theoretically predicted in 2010 and experimentally observed in 2019, is an exotic scattering phenomenon of light from subwavelength nanostructures. In principle, superscattering allows for an arbitrarily large total scattering cross section, due to the degenerate resonance of eigenmodes or channels. Consequently, the total scattering cross section of a superscatterer can be significantly enhanced, far exceeding the so-called single-channel limit. Superscattering offers a unique avenue for enhancing light-matter interactions and can enable numerous practical applications, ranging from sensing, light trapping, bioimaging, and communications to optoelectronics. This paper provides a comprehensive review of the recent progress and developments in the superscattering of light, with a specific focus on elucidating its theoretical origins, experimental observations, and manipulations. Moreover, we offer an outlook on future research directions in superscattering, including potential realizations of directional superscattering, scattering-free plasmonic superscattering, enhancement of free-electron radiation and the Purcell effect via superscatterers, inelastic superscattering, and superscattering of non-electromagnetic waves.

Regularized entanglement entropy of electron-positron scattering with a witness photon

Regularized quantum information metrics are calculated for the scattering process e−e+→γ,Z→μ−μ+ that has a witness photon entangled with the initial electron-positron state. Unitarity implies the correct regularization of divergences that appear in both the final density matrix and von Neumann entanglement entropies. The entropies are found to quantify uncertainty or randomness. The variation of information, entanglement entropy, and correlation between the muon’s and witness photon’s helicities are found to convey equivalent information. The magnitude of the muon’s expected helicity rises (falls) as the helicity entropy falls (rises). Area, or the scattering cross section, is a source of entropy for the muon’s helicity entropy and momentum entropy. The muon’s differential angular entropy distribution is similar to the differential angular cross section distribution, capturing the forward-backward asymmetry at high center-of-mass energies. Published by the American Physical Society 2024

Low-energy (0–9 eV) electron interaction with gas phase 1,3-dichlorobenzene: an experimental and theoretical study

Abstract Dichlorobenzene used widely in industry for the synthesis of complex products, such as polymers. The processes using this compound require, as the initial step, the breakage of the C–Cl bond. In this work, we study the interaction of electrons with 1,3 dichlorobenzene molecules not only below 2 eV [M Mahmoodi-Darian et al 2001 J. Phys. Chem. A 113 11923–14929] but also at higher energies, i.e., up to 10 eV. In this investigated energy range, the electron induces the cleavage of the C–Cl bond producing essentially a Cl− anion and the chlorobenzene radical via dissociative electron attachment. The experimental measurements are completed with quantum scattering treatments providing the resonant states and also the integral scattering cross sections. These outcomes may potentially contribute to elaborate synthesis strategies using electrons (i.e., cold plasma, surface plasmon resonance, …).

Positron interactions with vinyl acetate from 0.1 eV to 5 keV

Abstract Scattering cross sections from positron impact on vinyl acetate are explored in the energy region 0.1 eV to a 5 keV, employing a cc-pVTZ basis set. The optimized molecular wavefunction of the target was obtained through a multi-center expansion of Gaussian-type orbitals in the Hartree–Fock self-consistent field framework. The elastic cross sections are computed using the single-centre-expansion formalism. Two distinct models were employed to address the long-range effects associated with the target's polar nature and yielded almost identical corrections. The Born-corrected elastic cross sections align more strongly with the existing experimental corrected data than the results reported from the independent-atom-model approximation. The differential and momentum transfer cross sections after applying Born-correction are also reported. The direct ionization cross sections are obtained using the binary-encounter-Bethe model for positrons. The cross sections obtained by summing elastic and ionization cross sections align closely with ‘forward angle corrected’ experimental total cross sections across a significant energy range. The agreement significantly improves beyond 30 eV, suggesting that the omission of excitation and positronium formation cross sections becomes less significant. A brief analysis of the electron interaction with the target is also made.

Acoustic scattering and "failure" of the optical theorem.

For plane wave scattering by an obstacle, the optical theorem relates the scattering cross section to the far-field scattered field in the forward direction. This simple and useful result fails to hold when the incident field is not a plane wave. "Failures" of this kind are explored. For scattering by a sphere, an explicit formula for the scattering cross section is obtained, applicable to arbitrary incident fields.

Modeling of the tunable plasmonic properties of spherical and ellipsoidal silver nanoparticles in the matrix of an organic semiconductor

The object of research is the tunable plasmonic properties of spherical and ellipsoidal silver nanoparticles in the organic semiconductor matrix. The average absorption cross-sections, scattering cross-sections, and optical radiation efficiency of spherical and ellipsoidal silver nanoparticles have been simulated. The long-wave statistical approach has been used to model the optical parameters of the assembled spherical and ellipsoidal nanoparticles. Statistical averaging is used here, where absorption and scattering are considered from an «effective» particle with statistical properties. This approach avoids complex calculations considering the details of the spectral characteristics of single nanoparticles of different shapes. Taking into account the fact that the nanocomposite matrix will contain ensembles of spherical nanoparticles of different sizes, the peak of their absorption and scattering cross sections will be shifted to the short wavelength region of the spectrum compared to ensembles of the same spherical nanoparticles. In addition, there is a slight increase in the absorption cross-section and a decrease in the scattering cross-section, confirming the presence of smaller nanoparticles. A study was made of a composite material containing a randomly dispersed ensemble of silver ellipsoidal nanoparticles of the same and different shapes and sizes in an organic semiconductor matrix. An ensemble of identical ellipsoidal nanoparticles is characterized by the presence of two plasmon peaks, which corresponds to the characteristics of a single ellipsoidal nanoparticle. A completely different situation is observed if to consider that the nanocomposite will contain an ensemble of ellipsoidal nanoparticles of different shapes and sizes. Such nanoparticles will be characterized by a plasmon peak for both the absorption and scattering cross-sections. This can be explained by the fact that as the size of ellipsoidal nanoparticles decreases, the distance between the peaks responsible for the longitudinal and transverse modes of plasmon excitation decreases. An increase in the shape distribution leads to a broadening of the absorption and scattering cross-section spectra. The efficiency of the optical radiation increases as the size distribution increases. It is shown that a change in the refractive index of an organic semiconductor matrix mainly affects only the value of the scattering cross-section of an ensemble of ellipsoidal nanoparticles dispersed in it. This research is a preliminary step to studying the influence of these particles on the properties of organic light-emitting structures.

Elastic differential neutron-scattering cross section on even Neodymium isotopes

In this paper, we present an analytical formula for the neutron scattering cross section on even-even heavy nuclei, employing the rotational model and making certain assumptions, such as the use of the Yukawa potential shape for the neutron-nucleon interaction, the rigid rotor approximation, and the assumption of a uniformly distributed nuclear matter within the nucleus. Notably, a significant aspect of this study is the avoidance of any approximation of a central potential, in contrast to the commonly employed methods of expanding the potential based on the power of , utilizing the Legendre polynomial basis, or employing Fourier-Bessel analysis. Despite the simplicity of the chosen model (rigid rotor model and the two-parameter potential), our results yield satisfying and encouraging outcomes. This suggests the effectiveness of our approach in analyzing neutron scattering on even-even heavy nuclei. It is important to note that further investigations are warranted to deepen our understanding and refine the assumptions utilized in this study. Future research should explore the applicability of the proposed analytical formula to diverse nuclei and consider more complex models to expand our comprehension of neutron-nucleus interactions.

CVAE-based inverse design of two-dimensional honeycomb pentamode metastructure for acoustic cloaking

In this work, a method for inverse design of two-dimensional honeycomb pentamode metastructures (HPM) based on the Conditional Variational Auto-Encoder (CVAE) is proposed to achieve acoustic cloaking. The parameter distribution of the perfect acoustic cloak with two-dimensional cylindrical Kohn-Shen-Vogelius-Weinstein (KSVW) mapping is first derived. The CVAE model framework is then established along with its loss function in terms of the design parameters of the HPM. The inverse design performance of the deep generative model is evaluated using a large number of random test samples based on finite element simulations, showing that the equivalent mechanical parameters obtained from inverse design are highly consistent with the target parameters of the perfect acoustic cloak. For the HPM cloak design given by the trained deep generative model, the total scattering cross section (TSCS) is significantly reduced as compared to the case without a cloak, thereby demonstrating the effectiveness of the CVAE-based inverse design of acoustic cloak.

Topological features of trajectories of virtual photons and their effective interaction under multiple scattering in a system of conductive nanoparticles

It is shown that in conditions of strong light localization in a system of Rayleigh's resonance scatterers, effective photon–photon interaction appears. This interaction is associated with neither nonlinearity of medium nor nonlocal interaction of polarization-entangled photon pairs. It is related to complex topology of photon trajectories due to multiple scattering. Because of this interaction, acts of simultaneous elastic scattering of pair of photons in the considered system cease to be independent processes. The differential cross section of this cooperative process contains only an extra degree of small Rayleigh's factor in comparison with the classical scattering cross section of a single photon. This opens up the possibility of control of light fluxes by means of alternative low-intensity light fluxes without using slow optoelectronic converters. Light localization that provides the effective photon–photon interaction is considered in the framework of a new formalism different from traditional one. Equation of the Bethe–Salpeter for two-photon propagator is resolved directly in coordinate representation without traditional reducing of this equation to some transport equation. This allows in a new light to look on reason of weak light localization and to show that weak localization is one of consequences of strong localization.

Thermal cross section of poly(2-hydroxyethyl methacrylate) hydrogels for neutron dose calculation

Phantom materials are used to design radiation safety and protection strategies by means of numerical dose calculation. In the case of thermal neutrons, the radiation transport in the phantom relies on mass attenuation coefficients and total cross sections which are dependent on the physical and chemical properties of the material. Specifically for medical applications, such as neutron capture therapy, the neutron-induced dose is mainly related to the neutron absorption by hydrogen and nitrogen in the human tissue and body. Here, we investigate the use of poly(2-hydroxyethyl methacrylate) as a phantom material by experimental measurement and modeling of its total neutron scattering cross section and mass attenuation coefficient. We show that by varying the hydration level from 10 to 40 w%, one can obtain a neutron attenuation coefficient similar to polymethyl methacrylate or more representative of the human body, respectively. By benchmarking our phenomenological model on the experimental data, we provide a new example of how to use the average functional group approximation to accurately model total neutron cross sections in the framework of personalized medicine approaches.

Nonlinear light-output calibration of the oxygenated xylene scintillators used in OMEGA neutron time-of-flight spectrometers.

Neutron time-of-flight (nTOF) spectrometers are essential instruments for measuring and evaluating the performance of inertial confinement fusion implosions. The neutron spectrometers utilized for the OMEGA laser include two liquid-based scintillators, each consisting of a large volume filled with xylene that is coupled to four photomultiplier tubes. Analysis of the signal from these detectors requires detailed knowledge of the scintillator's light output, which is needed to fit the nTOF spectrum, from which the neutron energy spectrum is informed. The light output is nonlinearly proportional to the neutron energy, which, in turn, affects the interpretation of the neutron energy spectrum from a TOF signal. A recent campaign on OMEGA was performed to calibrate the xylene detectors and infer the shape of the light-output curve. The campaign utilized materials with increasing Z placed in the OMEGA target chamber to initiate scattering events with the 14MeV fusion neutrons. This process leads to the production of backscatter neutrons of varying energies that appear as peaks in the nTOF data. Simulations using a neutron transport code were combined with the measured deuterium-tritium neutron yields to calculate the expected backscattered neutron yields from the well-known scattering cross sections of each material. The neutron-energy dependent light output of the scintillator inferred from the experiment is compared to the light-output curve simulated with a neutron transport code for the following neutron energies: 1.5, 2.5, 6, and 14MeV.

Testing for coherence and nonstandard neutrino interactions in COHERENT data

We analyze data from the CsI, liquid Ar and Ge detectors of the COHERENT experiment and confirm within 1.5σ that the measured elastic neutrino-nucleus scattering cross section is proportional to the square of the number of neutrons in the nucleus, as expected for coherent scattering in the standard model. We also show how various degeneracies involving nonstandard neutrino interaction parameters are broken in a combined analysis of the three datasets. Published by the American Physical Society 2024

Charged current weak production of Δ(1232) induced by electrons and positrons

The charged current weak production of Δ(1232) from the free proton target induced by the electron/positron in the intermediate energy range corresponding to the beam energy available at JLab and Mainz, has been studied. The results for the differential scattering cross section dσdQ2, the angular distribution dσdΩΔ, and the total scattering cross section σ(Ee) for both the electron and positron induced processes are presented, for the various energies in the range of 0.5–4 GeV. The cross section σ(Ee) is found to be of the order of 10−39 cm2 for the electron/positron energies in the few GeV range. The availability of electron/positron beams having well-defined energy and direction with very high luminosity of the order of 1038–1039 cm−2 sec−1, makes it possible to observe the weak charged current production of Δ(1232) and determine the axial vector form factors CiA(Q2);(i=3–5). The sensitivity of the differential cross section dσdQ2 to the subdominant form factors C3A(Q2) and C4A(Q2) is found to be strong enough, especially in the low Q2 region, which can be used to determine them phenomenologically and to test the various theoretical models proposed to calculate them. Published by the American Physical Society 2024

Activity of main-belt comet 324P/La Sagra

We study the activity evolution of the main-belt comet 324P/La Sagra over time and the properties of its emitted dust. We performed aperture photometry on images taken by a wide range of telescopes at optical and thermal infrared wavelengths between 2010 and 2021. We derived the combined scattering cross section of the nucleus and dust (when present) as a function of time, and we derived the thermal emission properties. Fitting an IAU H-G phase function to the data obtained when 324P was likely inactive, we derived an absolute nucleus magnitude $H_R = (18.4 0.5)$ mag using $G = 0.15 0.12$. The activity of 324P/La Sagra during the 2015 perihelion passage has significantly decreased compared to the previous perihelion passage in 2010, and it decreased even further during the 2021 perihelion passage. This decrease in activity may be attributed to mantling or to the depletion of volatile substances. The $Af profile analysis of the coma of the main-belt comet suggests a near-perihelion transition from a lower-activity pre-perihelion to a higher-activity post-perihelion steady state. We calculate a dust geometric albedo in the range of (2 - 45)<!PCT!>, which prevents us from constraining the spectral type of 324P/La Sagra, but we found an indication of dust superheating at 4.5 µm.

Exact scattering cross section for lattice-defect scattering of phonons using the atomistic Green's function method

Exact scattering cross section for lattice-defect scattering of phonons using the atomistic Green's function method

Extraction of Molecular-Frame Electron-Ion Differential Scattering Cross Sections Based on Elliptical Laser-Induced Electron Diffraction.

We extracted the molecular-frame elastic differential cross sections (MFDCSs) for electrons scattering from N_{2}^{+} based on elliptical laser-induced electron diffraction (ELIED), wherein the structural evolution is initialized by the same tunneling ionization and probed by incident angle-resolved laser-induced electron diffraction imaging. To establish ELIED, an intuitive interpretation of the ellipticity-dependent rescattering electron momentum distributions was first provided by analyzing the transverse momentum distribution. It was shown that the incident angle of the laser-induced returning electrons could be tuned within 20° by varying the ellipticity and handedness of the driving laser pulses. Accordingly, the incident angle-resolved DCSs of returning electrons for spherically symmetric targets (Xe^{+} and Ar^{+}) were successfully extracted as a proof-of-principle for ELIED. The MFDCSs for N_{2}^{+} were experimentally obtained at incident angles of 4° and 7°, which were well reproduced by the simulations. The ELIED approach is the only successful method so far for obtaining incident angle-resolved ionic MFDCS, which provides a new sensitive observable for the transient structure retrieval of N_{2}^{+}. Our results suggest that the ELIED has the potential to extract the structural tomographic information of polyatomic molecules with femtosecond and subangstrom spatiotemporal resolutions that can enable the visualization of the nuclear motions in complex chemical reactions as well as chiral recognition.

Multidimensional construction of 1T-MoS2@graphene nanosheets nanocomposites for enhanced electromagnetic wave absorption

The preparation of electromagnetic (EM) wave absorption materials provided with the characteristics of thin matching thickness, broad bandwidth, and mighty absorption intensity is an efficient solution to current EM pollution. Herein, Graphene nanosheets (GN) were firstly fabricated via a facile high-energy ball milling method, subsequently high-purity 1T-MoS2 petals were uniformly anchored on the surface of GN to prepare 1T-MoS2@GN nanocomposites. Plentiful multiple reflection and scattering of EM waves in a distinctive multidimensional structure formed by GN and 1T-MoS2, copious polarization loss consisting of interfacial polarization loss and dipolar polarization loss severally derived from multitudinous heterointerfaces and profuse electric dipoles in 1T-MoS2@GN, and mighty conduction loss originated from plentiful induced current in 1T-MoS2@GN generated via the migration of massive electrons, all of which endowed 1T-MoS2@GN nanocomposites with exceptional EM wave absorption performances. The minimum reflection loss (RLmin) of 1T-MoS2@GN reached –50.14 dB at a thickness of only 2.10 mm, and the effective absorption bandwidth (EAB) was up to 6.72 GHz at an ultra-thin matching thickness of 1.84 mm. Moreover, the radar scattering cross section (RCS) reduction value of 36.18 dB m2 at 0° could be achieved as well, which ulteriorly validated the tremendous potential of 1T-MoS2@GN nanocomposites in practical applications.