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The work investigates thermoplasmonic phenomena in metallic nanoparticles of the different geometry. The relations for the frequency dependences of nanoparticle overheating and radiation efficiency, as well as the size dependence of Joule number, which characterizes the ability of nanoparticles to generate heat, were obtained. At the same time, the size dependences of the effective electron relaxation rate for cylindrical and disk particles are determined within the frameworks of the equivalent spheroid approach. The frequency dependences of polarizability, absorption and scattering cross-sections, overheating, radiation efficiency and the size dependences of Joule number were calculated for spherical, cylindrical and disk nanoparticles of the different sizes and different metals. It is shown that the number and positions of maxima of absorption and scattering cross-sections and overheating of metallic nanoparticles depend on their geometry and, in the case of 1D-particles, on their sizes (aspect ratio). The splitting of these maxima for cylindrical particles is significantly greater than for disk particles. The calculations demonstrate that the overheating of nanoparticles in the biological transparency windows ranges from fractions to a few degrees, except in the case of nanocylinders with the small aspect ratio, where the overheating maxima of silver nanoparticles fall within the first biological transparency window. It was established that the material of nanoparticles also significantly affects the position of their overheating maximum and is determined by the value of the plasma frequency. It is demonstrated the feasibility of using spherical, disk and short cylindrical nanoparticles in applications where negligible overheating in biological transparency windows is required. In the cases where the significant overheating is required, the use of long nanocylinders is appropriate. Fundamental differences in the behavior of Joule number (ability to generate heat) for particles of different geometries under the variation of their radius / aspect ratio have been found.

It is shown that the application of the universal Lindhard function for calculating the scattering cross section of atomic particles is, as a rule, limited to the region of scattering angles less than 20°. The results obtained for various popular interaction potentials are compared with the available experimental data. It is shown that the presence of inelastic channels in scattering leads to the appearance of additional maxima in the scattering cross section. Recommendations are given on the use of the universal Lindhard function to describe quasi-elastic scattering in the region η = εsin(θ/2) > 0.01, ε is the reduced impact energy, θ is the scattering angle. At high energies, the scattering is well described by screened Coulomb potentials, and the application of the Lindhard function provides an accuracy of 10% for calculating the scattering cross sections.

In this paper, we study the 3D elastic scattering problem of plane dyadic waves for a rigid body and a cavity in linear elasticity. Initially, for each case, we formulate the direct scattering problem in a dyadic form, and we give the corresponding longitudinal and transverse far-field scattering amplitudes. Due to dyadic formulation of the problems, the main outcome of this paper is to establish the necessary energy considerations as well as to present functionals and formulas for the differential and the scattering cross-section in order to measure the disturbance created by the scatterer to the propagation of the plane dyadic incident field. Further, we assume that our incident field is scattered by a “small” rigid body or cavity and relative results for low-frequency scattering are obtained. Finally, we prove similar corresponding expressions for energy functionals in the far-field region, along with expressions for the differential and the total scattering cross-section, which are recovered as special cases.

The scattering of electromagnetic waves by isotropic dielectric cylinders can be dramatically modified by means of vanadium dioxide (VO2) thin-film coatings. Efficient dynamic control of scattering is achieved due to the variations in material parameters realizable by means of external biasing. In this paper, we study the scattering of terahertz waves in a case where the coating shells are made of VO2, a phase-change material, whose thin films may work rather as electromagnetic phase screens in the insulator material phase, but as lossy quasi-metallic components in the metallic material phase. The shells that uniformly cover the dielectric cylinders are investigated. Attention will be paid to the demonstration of the potential of VO2 in the external control of diverse scattering regimes of the dielectric-VO2 core–shell scatterer, while conductivity of VO2 corresponds to rather insignificant variations in temperature. In line with the purposes of this work, it is shown that the different resonant and nonresonant regimes have different sensitivity to the variations in VO2 conductivity. Both the total scattering cross section and field distributions inside and around the core are studied, as well as the angle-dependent scattering cross section.

In this study the coherent scattering function ƒ(k) has been calculated for x-ray in Copper using the Wave function involving Slater’s roles approximation for the values 0 ≤ k ≤ 1.6 A 0-1 , The Rayleigh scattering cross section, has been calculated. The Rayleigh scattering cross section was found to be dominate at low energy, where the scattering cross section starting from very small energy and less than 1KeV, Also the increasing of angular distribution for Rayleigh scattering cross section is principle dependent on the value of atomic scattering factor f(k), and observed Rayleigh scattering decreasing at high energies, while it is more distinct at low energies, for this reason the Rayleigh scattering is very important at low energies, because the scattering angle is large.

In our recent publications, we presented neutral-current ν–nucleus cross-sections for the coherent and incoherent channels for some stable Mo isotopes, assuming a Mo detector medium, within the context of the deformed shell model. In these predictions, however, we have not included the contributions in the cross-sections stemming from the stable 94,96Mo isotopes (abundance of 94Mo 9.12% and of 96Mo 16.50%). The purpose of the present work is to perform detailed calculations of ν–94,96Mo scattering cross-sections, for a given energy Eν of the incoming neutrino, for coherent and incoherent processes. In many situations, the Eν values range from 15 to 30 MeV, and in the present work, we used Eν = 15 MeV. Mo as a detector material has been employed by the MOON neutrino and double-beta decay experiments and also from the NEMO neutrinoless double-beta decay experiment. For our cross-section calculations, we utilize the Donnelly–Walecka multipole decomposition method in which the ν–nucleus cross-sections are given as a function of the excitation energy of the target nucleus. Because only the coherent cross-section is measured by current experiments, it is worth estimating what portion of the total cross-section represents the measured coherent rate. This requires the knowledge of the incoherent cross-section, which is also calculated in the present work.

Based on the ideas used by Kiselev, we study three black holes surrounded by quintessence and the effects of quintessence on the classical and semiclassical scattering cross-sections. In contrast, the absorption section is studied with the sinc approximation in the eikonal limit. For Schwarzschild, Reissner–Nordström and Bardeen black holes surrounded by quintessence, the critical values of charges, and the normalization factor are obtained. We also described the horizons and the extremal condition of the black holes surrounded by quintessence, by setting the quintessence state parameter in the two particular cases ω = - 2 / 3 and ω = - 1 / 2 .

The discovery of orbital angular momentum (OAM) for the last three decades has made it very versatile for an extensive range of applications. It is an imperative tool for optical research community. So, in this study, we investigated the interaction of vortex electromagnetic (VEM) wave with a perfect electromagnetic conductor (PEMC) sphere. The PEMC is regarded as an extension of the perfect electric and the perfect magnetic conductors. The incident VEM wave fields are expanded by taking into account features of OAM and using spherical vector wave functions (SVWFs). The incident expansion coefficients for VEM wave are derived by means of the definite integrals. Various factors such as normalized differential scattering cross section (DSCS), OAM density, total time-averaged intensity and total field intensity in the context of the electric field amplitudes for scattered fields are computed and investigated. It is expected that findings of the study would be beneficial regarding interaction between the VEM waves and metamaterials in terms of optical diagnostics, optical tweezers and manipulation of spherical particles/surfaces. Findings from this study have applications in electromagnetic scattering and propagation, OAM imaging, particle characterization, measuring optical radiation force, radiative transfer processes, scattering asymmetry factor, remote sensing, radar technology, telecommunications systems and other domains. OAM density (linear + circular), total time-averaged intensity, total scattered electric field intensity and normalized DSCS have also been analyzed numerically. The influence of sphere size, beam waist radius and electromagnetic admittance is examined and discussed.

Optical properties of atmospheric particles at Mexico City (UNAM) and Queretaro (JQRO) were measured with a Photoacoustic Extinctiometer (PAX) at 870 nm. The Mexico City Metropolitan Area has around 21 million inhabitants and Queretaro Metropolitan Area has little more than a million. Observations of meteorological parameters (relative humidity, solar radiation, and wind speed) were used to identify the rainy and dry seasons and explain the daily and seasonal behaviors of particles optical properties. The measurements were made from November 1, 2014 to July 31, 2016. At UNAM, the mean values of the scattering coefficient (Bscat) in cold dry, warm dry, and rainy seasons were 35.8, 27.1, and 31.3 Mm−1, respectively; while at JQRO were 10.9, 11.9, and 15.0 Mm−1. The average values of the absorption coefficient (Babs) at UNAM during the cold dry, warm dry, and rainy seasons were 14.5, 12.7, and 12.7 Mm−1, respectively; whereas at JQRO were 4.9, 4.7, and 3.9 Mm−1. Both absorption and scattering coefficients showed similar diurnal behaviors, but at UNAM they are three times higher than JQRO. Concentrations of criteria gases (O3, NO, NO2 and NOx) were also measured. At UNAM no difference was observed between the seasonal values for the single scattering albedo (SSA); while in JQRO, the rainy season had the highest seasonal value, being 13% higher than in the dry seasons. The Mass Scattering Cross-Section (MSC) values at UNAM were close to 2 m2/g; on the other hand, at JQRO the MSC values were lower than 1 m2/g. The results suggest a seasonal variability in the aerosol optical properties in both sites, which should be verified with more long-term studies.

We report on an extensive semi-empirical analysis of scattering cross-sections for electron elastic collision with noble gases via the Markov Chain Monte Carlo-Modified Effective Range Theory (MCMC−MERT). In this approach, the contribution of the long-range polarization potential (∼r−4) to the scattering phase shifts is precisely expressed, while the effect of the complex short-range interaction is modeled by simple quadratic expression (the so-called effective range expansion with several adjustable parameters). Additionally, we test a simple potential model of a rigid sphere combined with r−4 interaction. Both models, the MERT and the rigid sphere are based on the analytical properties of Mathieu functions, i.e., the solutions of radial Schrödinger equation with pure polarization potential. However, in contrast to MERT, the rigid sphere model depends entirely upon one adjustable parameter—the radius of a hard-core. The model’s validity is assessed by a comparative study against numerous experimental cross-sections and theoretical phase shifts. We show that this simple approach can successfully describe the electron elastic collisions with helium and neon for energies below 1 eV. The purpose of the present analysis is to give insight into the relations between the parameters of both models (that translate into the cross-sections in the very low energy range) and some “macroscopic” features of atoms such as the polarizability and atomic “radii”.