Interaction Of Electromagnetic Radiation Research Articles

Microscopic theory of scattering of weak electromagnetic radiation by a dense ensemble of ultracold atoms

Based on the developed quantum microscopic theory, the interaction of weak electromagnetic radiation with dense ultracold atomic clouds is described in detail. The differential and total cooperative scattering cross sections are calculated for monochromatic radiation as particular examples of application of the general theory. The angular, spectral, and polarization properties of scattered light are determined. The dependence of these quantities on the sample size and concentration of atoms is studied and the influence of collective effects is analyzed.

Effect of radio-frequency electromagnetic radiations (RF-EMR) on passive avoidance behaviour and hippocampal morphology in Wistar rats

Introduction. The interaction of mobile phone radio-frequency electromagnetic radiation (RF-EMR) with the brain is a serious concern of our society.Objective. We evaluated the effect of RF-EMR from mobile phones on passive avoidance behaviour and hippocampal morphology in rats.Materials and methods. Healthy male albino Wistar rats were exposed to RF-EMR by giving 50 missed calls (within 1 hour) per day for 4 weeks, keeping a GSM (0.9 GHz/1.8 GHz) mobile phone in vibratory mode (no ring tone) in the cage. After the experimental period, passive avoidance behaviour and hippocampal morphology were studied.Results. Passive avoidance behaviour was significantly affected in mobile phone RF-EMR-exposed rats demonstrated as shorter entrance latency to the dark compartment when compared to the control rats. Marked morphological changes were also observed in the CA3 region of the hippocampus of the mobile phone-exposed rats in comparison to the control rats.Conclusion. Mobile phone RF-EMR exposure significantly altered the passive avoidance behaviour and hippocampal morphology in rats.

Interaction of electromagnetic radiation with a plasma with fully developed ion acoustic turbulence

A study is made of the characteristic features of the reflection and absorption of a monochromatic wave by a plasma with axisymmetric ion acoustic turbulence over a broad frequency range. The absorption anisotropy and the related conversion of an incident, linearly polarized wave into a reflected, elliptically polarized wave are described. The absorption coefficient and the difference in the phase shifts occurring in the reflection of different field components are obtained as explicit functions of the turbulent plasma parameters.

Formation of copper-containing fiber composite materials for microwave radiation screens

A new method is proposed for the synthesis of radio-wave-absorbing metal-containing composite materials based on polyacrylonitrile fibers. The interaction of electromagnetic radiation with samples of machine-knitted fabric made of copper-containing fibers has been studied in an 8–12 GHz frequency range. The chemical composition of the synthesized materials has been determined. The possible applications of new materials and related structures for the screening of stray electromagnetic radiation of data-processing devices and electronic components and suppressing negative effects of high-frequency electromagnetic fields are considered.

Comparison of scattering experiments using synchrotron radiation with Monte Carlo simulations using Geant4

Monte Carlo techniques are powerful tools to simulate the interaction of electromagnetic radiation with matter. One of the most widespread simulation program packages is Geant4. Almost all physical interaction processes can be included. However, it is not evident what accuracy can be obtained by a simulation. In this work, results of scattering experiments using monochromatized synchrotron radiation in the X-ray regime are quantitatively compared to the results of simulations using Geant4. Experiments were performed for various scattering foils made of different materials such as copper and gold. For energy-dispersive measurements of the scattered radiation, a cadmium telluride detector was used. The detector was fully characterized and calibrated with calculable undispersed as well as monochromatized synchrotron radiation. The obtained quantum efficiency and the response functions are in very good agreement with the corresponding Geant4 simulations. At the electron storage ring BESSY II the number of incident photons in the scattering experiments was measured with a photodiode that had been calibrated against a cryogenic radiometer, so that a direct comparison of scattering experiments with Monte Carlo simulations using Geant4 was possible. It was shown that Geant4 describes the photoeffect, including fluorescence as well as the Compton and Rayleigh scattering, with high accuracy, resulting in a deviation of typically less than 20%. Even polarization effects are widely covered by Geant4, and for Doppler broadening of Compton-scattered radiation the extension G4LECS can be included, but the fact that both features cannot be combined is a limitation. For most polarization-dependent simulations, good agreement with the experimental results was found, except for some orientations where Rayleigh scattering was overestimated in the simulation.

Motion of dust in mean motion resonances with planets

Effect of stellar electromagnetic radiation on motion of spherical dust particle in mean-motion orbital resonances with a planet is investigated. Planar circular restricted three-body problem with the Poynting-Robertson (P-R) effect yields monotonous secular evolution of eccentricity when the particle is trapped in the resonance. Elliptically restricted three-body problem with the P-R effect enables nonmonotonous secular evolution of eccentricity and the evolution of eccentricity is qualitatively consistent with the published results for the complicated case of interaction of electromagnetic radiation with nonspherical dust grain. Thus, it is sufficient to allow either nonzero eccentricity of the planet or nonsphericity of the grain and the orbital evolutions in the resonances are qualitatively equal for the two cases. This holds both for exterior and interior mean-motion orbital resonances. Evolutions of longitude of pericenter in the planar circular and elliptical restricted three-body problems are shown. Our numerical integrations suggest that any analytic expression for secular time derivative of the particle's longitude of pericenter does not exist, if a dependence on semi-major axis, eccentricity and longitude of pericenter is considered (the P-R effect and mean-motion resonance with the planet in circular orbit is taken into account). Change of optical properties of the spherical grain with the heliocentric distance is also considered. The change of the optical properties: i) does not have any significant influence on secular evolution of eccentricity, ii) causes that the shift of pericenter is mainly in the same direction/orientation as the particle motion around the Sun. The statements hold both for circular and noncircular planetary orbits.

Characterization of conducting polymer coated fabrics at microwave frequencies

Purpose – The purpose of this paper is to investigate microwave reflection, transmission, and complex permittivity of p‐toluene‐2‐sulfonic acid doped conducting polypyrrole coated nylon‐lycra textiles in the 1‐18 GHz frequency with a view to potential applications in the interaction of electromagnetic radiation with such coated fabrics.Design/methodology/approach – The chemical polymerization of pyrrole is achieved by an oxidant, ferric chloride and doped with p‐toluene sulfonic acid (pTSA) to enhance the conductivity and improve stability. Permittivity of the conducting textile substrates is performed using a free space transmission method accompanied by a mathematical diffraction reduction method.Findings – The real part of permittivity increases with polymerization time and dopant concentration, reaching a plateau at certain dopant concentration and polymerization time. The imaginary part of permittivity shows a frequency dependent change throughout the test range. All the samples have higher values of...

A review of the effects of light scattering on the dynamics of irregularly shaped dust grains in the Solar System

The various aspects of the interaction of electromagnetic radiation with cosmic dust particles are discussed. In particular, attention is paid to discrepancies between optical and physical behavior of realistically shaped particles and volume equivalent homogeneous spheres. The dynamical evolution of morphologically non-identical particles which are driven by gravity, electromagnetic radiation and the Lorentz forces can dramatically differ. Although spherical particles often enable analytical calculations, an orbital evolution of spheres cannot be considered as a representative evolution for real cosmic dust particles. The effect of electromagnetic radiation on the motion of dust grains plays a crucial role here. While irregularly shaped interstellar dust particles may be captured in the Solar System, the spherical particles will not survive due to close encounters with the Sun. Spherical grains can be captured almost only in the evaporation region (in the vicinity of the Sun), where they are destroyed due to high temperatures. The spherical dust particles ejected from comets will monotonously inspiral toward the Sun subject to the Poynting–Robertson effect. However, the non-spherical particles of the same origin may be temporarily stabilized at some heliocentric distances and thus their lifetime may be much longer than that for the Mie spheres. Some dust particles may also be captured in mean-motion resonances with planets (commensurability resonances). While spherical particles are always characterized by the secular decrease of the semi-major axes near mean-motion resonances, this may not be true for non-spherical particles. Resonant captures of arbitrarily shaped dust grains exist for exterior and interior mean-motion resonances with planets.

Artificial Enzyme Catalysis Controlled and Driven by Light

Bio-inspired chemistry based on photoresponsive molecules is a rapidly developing new strategy to mimic the function of various biological systems. The interaction of electromagnetic radiation with molecular systems is ideally suited for the control and powering of dynamic processes at the speed of light. Besides typical applications in artificial photosynthesis, many other aspects, such as the catalytic turnover of substrates or the controlled release or uptake of small bioactive molecules, are readily verified with light-driven model systems. The potential of this novel approach in biomimetic chemistry is briefly explored in this concept article.

Influence of low-intensity electromagnetic millimeter radiation on the vital activity of Saccharomyces cerevisiae cells

Two mechanisms (bubble and resonance) of the interaction of low-intensity millimeter electromagnetic radiation and model cellular systems are investigated based on the example of Saccharomyces cerevisiae. It is shown that the effect of stimulating cell activity through electromagnetic radiation is of a pronounced resonance nature. The effect caused by the stimulation of vital activity in yeast cells under the influence of a thermal pulse, which can be described in terms of the bubble mechanism, is presented. The possibility of implementing both mechanisms is shown.

Synthesis of nanostructured sol–gel ITO films at different temperatures and study of their absorption and photoluminescence properties

Nanostructured indium tin oxide (ITO) films were deposited on silica glass by sol–gel dipping method from salt derived PVA based aqueous precursor. The films were cured at 250 °C, 350 °C, 450 °C, 600 °C, 700 °C and 900 °C and characterized by XRD, SEM, AFM techniques to observe heating effect on nanostructured feature. Nanocluster sizes were determined by TEM study. Different crystal phases of ITO were existed in the temperature range 250–900 °C. Quantum confinement behavior of the nanoclusters was observed for their size being near Bohr radius. Absorption, band gap and photoluminescence behavior of the nanstructured ITO films supported excitonic transitions due to the formation of electron hole pair generated by interaction of electromagnetic radiation.

Contribution to the theory of the interaction of electromagnetic radiation with a Bose-Einstein condensate of magnons

An attempt is made to analyze the dependence of the Raman scattering cross section or the absorption∕emission of electromagnetic waves by a Bose-Einstein condensate of magnons on their (magnons) density. Specifically, the intensities of one- and two-magnon transitions are compared and it is concluded that latter dominate in a Bose condensate. The salient features and possible role of the intermagnon interaction are discussed briefly.

Subgridding in the finite-difference time-domain method for simulating the interaction of terahertz radiation with metal

Simulating the interaction of electromagnetic terahertz radiation with metals poses difficulties not encountered in the optical regime. Owing to a penetration depth small compared to the wavelength, such simulations in the terahertz frequency range require large discretization volumes with very small grid spacings. We present a unique subgridding scheme that accurately describes this interaction while keeping computational costs minimal. Bidirectional coupling between grids allows for the complete integration of subdomains into the simulation volume. Implementation in one and two dimensions is demonstrated, and a comparison with theoretical and experimental results [Opt. Express15, 6552 (2007)] [Phys. Rev. B69, 155427 (2004)] is given. Using our technique, we are able to accurately simulate plasmonic effects in terahertz experiments for the first time.

Nonresonant power transfer in plasma-surface interactions via two-surface wave decay

The excitation of pairs of electron surface waves via nonresonant decay of plasma waves incident onto a solid surface is studied in the context of controlling the interaction of pulsed electromagnetic radiation with plasma-exposed solid surfaces. The role of the plasma-exposed surfaces in nonlinear heating of the plasma edge and related power transfer is discussed. It is shown that the maximum efficiency of the power transfer at solid surfaces with dielectric permittivity εd<3 corresponds to the resonant two-surface wave decay. On the other hand, for solids with εd>3 the maximum power transfer efficiency is achieved through nonresonant excitation of the quasistatic surface waves. In this case the plasma waves generated by external radiation dissipate their energy into the plasma periphery most effectively.

Two-surface wave decay: Controlling power transfer in plasma-surface interactions

Controlled interaction of high-power pulsed electromagnetic radiation with plasma-exposed solid surfaces is a major challenge in applications spanning from electron beam accelerators in microwave electronics to pulsed laser ablation-assisted synthesis of nanomaterials. It is shown that the efficiency of such interaction can be potentially improved via an additional channel of wave power dissipation due to nonlinear excitation of two counterpropagating surface waves, resonant excitations of the plasma-solid system.

On electric-quadrupole and magnetic-dipole contributions to optical rectification in isotropic media near optical resonance

A molecular theory of resonant optical rectification via the second-order electric-dipole polarizability related to the magnetic-dipole and electric-quadrupole interaction of electromagnetic radiation with atoms and molecules of an isotropic medium is presented. The magnetic-dipole and electric-quadrupole contributions to dc electric-dipole polarization can be produced by arbitrarily polarized light which has to be at resonance with the molecule. This effect can appear in an isotropic medium composed of molecules with arbitrary symmetries.

Particle acceleration by stimulated emission of radiation: Theory and experiment

The interaction of electromagnetic radiation with free electrons in the presence of an active medium has some appealing outcomes. Among them is particle acceleration by stimulated emission of radiation (PASER). In its framework, energy stored in an active medium (microscopic cavities) is transferred directly to an e -beam passing through. We have developed a two-dimensional analytic model for the evaluation of the energy exchange occurring as a train of electron microbunches traverses a dilute resonant medium. Efficient interaction occurs at resonance-namely, when the frequency of the train matches the resonance frequency of the medium. It is shown that the energy exchange is gamma independent for relativistic energies and it drops dramatically with an increase of the beam's radius. Based on this model, we have evaluated the relative change in the kinetic energy of a 0.1-nC 45-MeV macrobunch traversing an excited CO2 gas mixture-the former being modulated at the CO2 laser wavelength. Good agreement is found between the theoretical predictions and the results of the PASER experiment performed recently at Brookhaven National Laboratory.

General foundation for the nonlinear ponderomotive four-force in laser-plasma interactions

The interaction of electromagnetic radiation with plasmas is studied in relativistic four-vector formalism. A gauge and Lorentz invariant ponderomotive four-force is derived from the time dependent nonlinear three-force of Hora (1985). This four-force, due to its Lorentz invariance, contains new magnetic field terms. A new gauge and Lorentz invariant model of the response of plasma to electromagnetic radiation is then devised. An expression for the dispersion relation is obtained from this model. It is then proved that the magnetic permeability of plasma is unity for a general reference frame. This is an important result since it has been previously assumed in many plasma models.

Electromagnetic Response of Broken-Symmetry Nanoscale Clusters

A microscopic, nonlocal response theory is developed to model the interaction of electromagnetic radiation with inhomogeneous nanoscale clusters. The breakdown of classical continuum-field Mie theory is demonstrated at a critical coarse-graining threshold, below which macroscopic plasmon resonances are replaced by molecular excitations with suppressed spectral intensity.

Determination of the metal nanometer layer thickness and semiconductor conductivity in metal-semiconductor structures from electromagnetic reflection and transmission spectra

Interaction of electromagnetic radiation with metal-semiconductor nanometer structures is studied theoretically and experimentally. A technique for nondestructive multiparametric control of the electrophysical parameters of metal nanometer layers and semiconductor conductivity in metal-semiconductor structures using electromagnetic reflection and transmission spectra is proposed and tested experimentally.