Homogenization principles and effect of mixing on dielectric behavior

This paper consists of two parts. First, a review of classical mixing principles lists the multitude of the various ways to characterize the effective permittivity of heterogeneous materials. Different connections between the various mixing formulas are underlined and the homogenization principles are classified into families of mixing rules. The second part emphasizes and analyzes the richness of the manner how the mixing process is able to create new types of dielectric behaviors, in particular with respect to enhancement of dielectric polarization, shifts of the dispersion parameters, and emergence of new effects in electrical response.Non Peer reviewe

Dielectric Polarization and Particle Shape Effects

This article reviews polarizability properties of particles and clusters. Especially the effect of surface geometry is given attention. The important parameter of normalized dipolarizability is studied as function of the permittivity and the shape of the surface of the particle. For nonsymmetric particles, the quantity under interest is the average of the three polarizability dyadic eigenvalues.The normalized polarizability, although different for different shapes, has certain universal characteristics independent of the inclusion form. The canonical shapes (sphere, spheroids, ellipsoids, regular polyhedra, circular cylinder, semisphere, double sphere) are studied as well as the correlation of surface parameters with salient polarizability properties. These geometrical and surface parameters are essential in the material modeling problems in the nanoscale.Peer reviewe

Polarizability of a tri-isotropic sphere

This report presents the polarizability matrix of a tri-isotropic sphere. A tri-isotropic material exhibitscoupling between electric, magnetic, and in addition, a third kind of material response. Each of these threefields creates three different kind of polarizations. The paper derives the polarizability components of such asphere in vacuum and makes physical interpretations of the results for the copolarizabilities and cross polarizabilities.Peer reviewe

Studies on polarizabilities and scattering behavior of small spherical particles

It is possible to relate the response of a sphere to an applied uniform static electric field with the scattering from a small spherical particle due to plane wave incidence. The limits up to which these relations between the polarizability and the extinction, scattering, and radar cross sections of a sphere are valid in the dynamic range are presented here. From the observations it can be concluded that radar cross section is a very good measure in predicting the polarizability. A related aspect studied here is the evaluation of the effective permittivity of a sparse mixture of spherical inclusions using a generalized Maxwell Garnett mixing rule. This is compared with extinction of a plane wave by a slab of n spherical inclusions sparsely located. The extinction by such a slab is calculated using the quasistatic approximation to Mie theory, and also using the full Mie theory, as the size of the inclusions is increased. The studies have been carried out for both lossless and lossy inclusions. The generalized mixing rule was found to be quite accurate in predicting the value of effective permittivity up to size parameters of 0.5 at least for small εr of the inclusion.Peer reviewe

Eigenvector approach for solving nonisotropic mixing formulas

This paper deals with mixtures of nonisotropic media. The mixing formulas to describe the effective material parameters of the mixture are complicated expressions where the different parameter dyadics are coupled. Using six-vector notation, the different mixing rules become more manageable. However, for certain effective theories the matrix equations have been tractable only through numerical approach. Here we present a way to solve the effective material parameters in closed form, using an approach where the eigenvectors of the material six matrix are exploited. As a numerical example, the effective parameters of a mixture are calculated where the inclusion material is a mirror image of the background medium.Peer reviewe

Maximal Interaction of Electromagnetic Radiation with Corona-Virions

Absorption and scattering of the impinging electromagnetic waves are the two fundamental operations describing the energy exchange of any, organic or inorganic, particle with its environment. In the case of virion cells, substantial extinction power, counting both absorbing and scattering effects, is a prerequisite for performing a variety of coupling actions against the viral particles and, thus, a highly sought-after feature. By considering realistic dispersion for the dielectric permittivity of proteins and a core-shell modeling allowing for rigorous formulation via Mie theory, we report optical extinction resonances for corona-virions at mid-infrared range that are not significantly perturbed by changes in the objects size or the background host. Our findings indicate the optimal regime for interaction of photonic radiation with viral particles and may assist towards the development of equipment for thermal damage, disintegration or neutralization of coronavirus cells.Comment: 8 pages, 7 figures. Submitted to: APL Photonics, special topic on "Coronavirus and Photonics

Electromagnetic boundary and its realization with anisotropic metamaterial

A set of boundary conditions requiring vanishing of the normal components of the D and B vectors at theboundary surface is introduced and labeled as that of DB boundary. Basic properties of the DB boundary arestudied in this paper. Reflection of an arbitrary plane wave, incident with a complex propagation vector, isanalyzed for the planar DB boundary. It is shown that waves polarized transverse electric TE and transversemagnetic TM with respect to the normal of the boundary are reflected as from respective perfect electricconductor and perfect magnetic conductor planes. The basic problem of current source above the planar DBboundary is solved by applying TE and TM decomposition for the source. Realization of the DB boundary interms of an interface of uniaxially anisotropic metamaterial half-space with zero axial medium parameters isconsidered. It is also shown that such a medium with small axial parameters acts as a spatial filter for wavesincident at the interface which could be used for narrowing the beam of a directive antenna. Application of DBboundary as an isotropic soft surface with low interaction between antenna apertures also appears possible.Peer reviewe

On Modeling Perfectly Conducting Sharp Corners With Magnetically Inert Dielectrics Of Extreme Complex Permittivities

The idea of replacing an edgy perfectly conducting boundary by the corresponding interface filled with a dielectric material of extreme complex permittivities, is examined in the present work. A semi-analytical solution to the corresponding boundary value problems is obtained and the merit of the modeling has been checked. Certain conclusions for the effect of the constituent material parameters and the geometric features of the configuration on the model effectiveness, are drawn and discussed.Comment: 8 pages, 17 figures, research journa