Electrodynamic properties of matrix dispersed systems with two-layer inclusions

Theoretical approach for calculation of the effective dielectric permittivity (ē) of matrix dispersed systems (MDS) that consist of a dielectric matrix with randomly arranged two-layer spherical inclusions of different radiuses has been proposed and departures from the Maxwell-Garnet formula due to increasing of an inclusion volume fraction are studied. It is shown that the effects of direct dipole-dipole interactions between inclusions become important in this case. In the electrostatic approximation we have exactly solved the problem of a response of this N–particle system on the external electric field and obtained corrections to the Maxwell-Garnet formula for ē with account of the pair dipole-dipole interaction between inclusions

Optical properties of metal-composite-based thin films

In the first part of this work we study the effect of a semi-infinite matrix dispersed system (MDS) on the external electromagnetic radiation in the electrostatic approximation. With the help of our previous technique, we obtain general expressions for the multipole expansion coefficients of the electric potential for a sphere accounting for the interaction between ambient particles and the substrate. The polarizability tensor and resonant frequencies of a single sphere show anisotropy due to the influence of a substrate. In the second part electrodynamical properties of thin percolating layers manufactured on the basis of the MDS are considered. Transition from 3-D to 2-D behavior, which is observed near the percolation threshold and shows itself as changing of some parameters (in comparison with those for 3-D percolating system) like the values of percolation threshold, critical indices of conductivity and permittivity, were studied

The Rahman-Nat diffraction on a thin laser-induced grating of the refractive index in semiconductors

Studied in this work is the Rahman-Nat diffraction on a thin grating of refractive index in semiconductor, which was created by an interference pattern of two coherent laser beams. Numeral calculations showed that the maximal diffraction efficiency for the Rahman-Nat diffraction in the first order was 28.2 % for a purely phase grating at its thickness z ~ 200, and 4.8 % for a purely amplitude grating. It was also ascertained, that waves belonging to the nearby diffraction orders differ from each other by π/2 in their phase

Study of water diffusion in lymphocyte membranes from thymus gland and spleen of rats by method of quasi-elastic scattering of slow neutrons

The aqueous suspensions of lymphocyte membranes from the rat thymus gland and spleen cells were studied by the method of a quasi-elastic neutron scattering. Effect of X-ray irradiation on dynamics of water molecules in suspension of such membranes was examined. It was shown that a diffusion coefficient of water molecules decreases with increasing of a dose of X-ray irradiation animals (rats) from 0.5 up to 1.0 Gray

Optical surface modes in a system of fine metallic particles

The interaction of electromagnetic radiation with a low-density disordered system of fine metallic particles located in a dielectric matrix is considered in a quasi-static approach with allowance for dipole-dipole interaction. The electric dipole moment of the system is calculated in a pair approximation. The case of nonidentical particles differing in their sizes or dielectric functions is presented. Allowance for particle nonidentity leads to doubling of the number of their surface modes and to the appearance of band gaps in the spectrum. The spectrum peculiarities are revealed in the fine structure of electromagnetic absorption

Some Aspects of the Absorption of Electromagnetic Radiation by Heterogeneous Systems

This paper describes the results of studies of the interaction of electromagnetic radiation and a heterogeneous system (HS) where the relevant accounting interfaces are generalized. The results obtained have been used for the calculation of the dielectric loss in a matrix disperse system (MDS) consisting of an aggregate of SiO 2 particles (particle size ∼10 −7 m) covered with hydrate. It has been shown that the dielectric loss in such systems occurs on the level of the imaginary part ɛ ˜ ″ ∼ 0.1 ∼0.1 at a frequency of 10 7 Hz. The absorption mechanism of electromagnetic radiation caused by the surface modes of an MDS with metallic inclusions of a spherical and ellipsoidal shape has been studied. It is shown that resonance absorption of the electromagnetic radiation is observed at the frequencies of the surface modes. The spectral characteristics of ɛ ˜ ″ ( ω ) as a function of the parameters of the MDS have also been considered

Laser ablation lithography on thermoelectric semiconductor

In this paper, experimental results of the investigation of the periodic structure on thermoelectric semiconductor Cu2Se are presented. Periodic structures were formed on surfaces of semiconductors due to multi-beam interaction of Q-switched Nd:YAG laser, which was operated in the lowest order of Gaussian mode and pulse duration 7ns. Surface temperature evolution and transient reflectivity are studied during laser treatment. Creation of Cu islands in the maximal intensity of interference pattern was found