Search results for "electromagnetic radiation"
showing 10 items of 755 documents
Van der Waals Interactions in a Magneto-Dielectric Medium
2007
The van der Waals interaction between two ground-state atoms is calculated for two electrically or magnetically polarizable particles embedded in a dispersive magneto-dielectric medium. Unlike previous calculations which infer the atom-atom interaction from the dilute-medium limit of the macroscopic, many-body van der Waals interaction, the interaction is calculated directly for the system of two atoms in a magneto-dielectric medium. Two approaches are presented, the first based on the quantized electromagnetic field in a dispersive medium without absorption and the second on Green functions that allow for absorption. We show that the correct van der Waals interactions are obtained regardle…
Suppression of radiative losses of surface polaritons on nanostructured thin metal films
2005
The strong electromagnetic coupling between surface plasmon polariton modes on opposite interfaces of a finite thickness periodically nanostructured metal film has been studied. Surface polariton dispersion and associated electromagnetic field distributions have been analyzed. It was shown that at a frequency that corresponds to the crossing of film Bloch modes of different symmetries, the radiative losses of surface polaritons that are related to the polaritons' coupling to light during propagation on the structured surface are suppressed.
Combined Effects of 50 Hz Electromagnetic Field and SiO2 Nanoparticles on Oxidative Stress in Plant’s Gametic Cells / Zemfrekvences (50 Hz) Elekromag…
2015
Abstract The paper presents the results of combined effects of an extremely low frequency electromagnetic field (50 Hz) (ELF EMF) and SiO2 nanoparticles on fluorescence of plant gametic cells (immature microspores). The data were recorded by a BD FACSJazz® cell sorter after cell irradiation by blue laser (488 nm). A significant difference of fluorescence was observed between gametic cells after 1 hour incubation in suspension of SiO2 nanoparticles and the control gametic cells. It was observed that fluorescence intensity of gametic cell was higher with ELF EMF treatment in comparison to control cells, but it was statistically significant only for cells treated with electromagnetic radiation…
Cathodoluminescence study of undoped GaN films: Experiment and calculation
2009
Abstract In this paper, we report the theoretical and experimental results of cathodoluminescence (CL) from GaN layers grown at 800 °C by metal organic vapor phase epitaxy (MOVPE) on silicon substrate. The CL spectra recorded at room temperature reveal the near band-edge emission at 3.35–3.42 eV and a broad yellow luminescence at 2.2 eV. The CL depth analysis at constant power excitation shows inhomogeneous CL distribution in depth of these emissions as the electron beam increases from 3 to 25 keV. There appears a blue shift of the CL band-edge peaks with increasing sample depth. This behavior is explained by a change of the fundamental band gap due to residual strain and the local temperat…
Azatruxene‐Based, Dumbbell‐Shaped, Donor–π‐Bridge–Donor Hole‐Transporting Materials for Perovskite Solar Cells
2020
Three novel donor-π-bridge-donor (D-π-D) hole-transporting materials (HTMs) featuring triazatruxene electron-donating units bridged by different 3,4-ethylenedioxythiophene (EDOT) π-conjugated linkers have been synthesized, characterized, and implemented in mesoporous perovskite solar cells (PSCs). The optoelectronic properties of the new dumbbell-shaped derivatives (DTTXs) are highly influenced by the chemical structure of the EDOT-based linker. Red-shifted absorption and emission and a stronger donor ability were observed in passing from DTTX-1 to DTTX-2 due to the extended π-conjugation. DTTX-3 featured an intramolecular charge transfer between the external triazatruxene units and the azo…
Absorption equipment for energy savings: A case study in Sicily
2013
Abstract This paper considers a feasibility study on the recovery of the reject heat available from an electric utility with two units operating with 120-MW gas turbines; these units have a heat recovery system that feeds the district heating pipeline of an industrial consortium. Thus, feeding the expeller of the absorption equipment installed in a cooling plant for foodstuff stocking represents an opportunity for the feasibility study. This plant operates at both 0 °C and −18 °C. The feasibility study covers two aspects: (1) the technical feasibility of a suitable absorption cooling plant that uses two separate pieces of absorption equipment working with the pair ammonia–water and (2) the …
Electric Power Quality Evaluation in the Presence of Electromagnetic Emissions
2013
The measurements for the assessment of the electric power quality are often carried out in hostile electromagnetic environments. The aim of the paper is analyzing if and how both radiated and conducted electromagnetic emissions can disturb the measurement system used to quantify these disturbances. To achieve the target, an experimental approach is proposed, which, by means of a simple and fast test, allows establishing if the real electromagnetic environment, where power quality analysis is performed, can alter the measurements. © 2013 IEEE.
Transmission line meshes for computational simulation of electromagnetic modes in the Earth's atmosphere
2007
PurposeTwo transmission line meshes to simulate electromagnetic waves in the Earth's atmosphere are developed, one with the link transmission lines connected in parallel and the other with connections in series.Design/methodology/approachThe equations describing propagation of waves through these parallel or series meshes are equivalent to the Maxwell equations for TEr or TMr modes in a spherical cavity with lossy dielectric material between the external conducting surfaces, respectively.FindingsThe transmission line meshes are used for a numerical study of the natural electromagnetic noise due to lightning discharges in the Earth‐ionosphere cavity.Originality/valueThe numerical algorithm f…
Adapting available finite element structural programs to solve three-dimensional high frequency electromagnetic problems
1991
The adaptation of available structural mechanics software to solve microwave problems is possible by the analogy between the differential equations. A brief review of the analogy between transverse or shear waves in elasticity and electromagnetic waves is presented, followed by a more detailed discussion of the adaptation of a program to obtain the resonant frequencies of a rectangular resonant cavity, doing a three-dimensional analysis. The geometry of the electric field is also obtained for the resonant modes.
Optical properties and quantum yield determination in photocatalytic suspensions
2006
Knowledge of the optical properties of photocatalytic suspensions is vital for a correct comparison of their energetic efficiency. In this work, the determination of both absorption and scattering coefficients of aqueous suspensions of commercial TiO2 powders irradiated by monochromatic light was carried out by measuring only one quantity—the transmitted photon flow—as a function of the catalyst mass and by applying an asymptotic form of the Kubelka–Munk solution of the radiative transfer equation. Applying a nonlinear fitting procedure the evaluation of the actual values of absorption and scattering coefficients was carried out. The limit for optically thick media of the Kubelka–Munk equat…