Orientation Of Electric Field Research Articles

Photoelectric charging and lofting of dust particles on a conducting surface with external electric fields

We present a laboratory study of photoelectric charging of dust particles and their lofting on a conducting surface in the presence of external electric fields. Insulating particles with diameter <45 μm are dispersed on a conducting surface exposed to ultraviolet (UV) light. In addition to the UV exposure, a positive or negative external electric field is applied. Independent of the orientation of the external electric field, the dust particles are found to be positively charged but with different mechanisms. It is shown that the orientation of the external electric field controls the dynamics of photoelectrons emitted from the dust particles and the conducting substrate surface. Distinctly different lofting results are shown between these two electric field cases. The results provide insight for understanding dust charging and release and helping develop mitigation solutions in particle accelerators, semiconductor manufacturing, fusion reactors, and space exploration to planetary bodies.

Effect of the electric field orientation on stark shift, dipole moment and electronic properties in a circular toroidal quantum ring: Presence of shallow donor impurity

This research investigates the influence of electric field orientation on the physical properties of a Gallium Arsenide (GaAs) Circular Toroidal Quantum Ring (CTQR) in the presence of shallow donor impurity. Using the effective mass approximation and an infinite potential well, we delve into how electric field directions specifically 0, 45, and 90 degrees on the xy-plane affect physical behaviors such as binding energy, electronic energy, the Stark effect, dipole moment and donor impurity position. Utilizing the finite difference method for our numerical analysis, we discovered interesting size-dependent behaviors. Our findings reveal intriguing insights. Initially, we observed that the electronic energy exhibits minimal sensitivity to the direction of the electric field in smaller CTQR. Notably, the ground state energy increases when the electric field’s direction shifts from φF=0 to φF=90∘. The electric field’s influence on the binding energy varies depending on its orientation. In larger structures, we observe a lower binding energy. Thus, our study unveils the influence of the electric field’s direction on Stark shifts and dipole moment which opens pathways for a deeper understanding of potential applications in this domain.

In-plane gate induced transition asymmetry of spin-resolved Landau levels in InAs-based quantum wells

The crossover from quasi-two- to quasi-one-dimensional electron transport subject to transverse electric fields and perpendicular magnetic fields is studied in the diffusive to quasi-ballistic and zero-field to quantum Hall regime. In-plane gates and Hall-bars have been fabricated from an InGaAs/InAlAs/InAs quantum well hosting a 2DEG with a carrier density of about 6.8 × 1011 cm−2, a mobility of 1.8 × 105 cm2/Vs, and an effective mass of 0.042me after illumination. Magnetotransport measurements at temperatures down to 50 mK and fields up to 12 T yield a high effective Landé factor of g*=16, enabling the resolution of spin-split subbands at magnetic fields of 2.5 T. In the quantum Hall regime, electrostatic control of an effective constriction width enables steering of the reflection and transmission of edge channels, allowing a separation of fully spin-polarized edge channels at filling factors ν = 1 und ν = 2. A change in the orientation of a transverse in-plane electric field in the constriction shifts the transition between Zeeman-split quantum Hall plateaus by ΔB ≈ 0.1 T and is consistent with an effective magnetic field of Beff ≈ 0.13 T by spin-dependent backscattering, indicating a change in the spin-split density of states.

Multiscale insights into electric field orientation effects on piezoelectric strain and crystallography in P(VDF–TrFE) and P(VDF–TrFE–CTFE) fibers

This research primarily focuses on the effect of changing electric field directions on the crystal structure of piezoelectric fibers, notably, P(VDF–TrFE) and P(VDF–TrFE–CTFE). The study also explores the deformation mechanisms of fibers at micro- and nanoscales. A significant aspect of the research involves the application of parallel and perpendicular electric fields and observation of their impact on fiber properties. In situ wide-angle X-ray diffraction (WAXD) studies are crucial for determining the nanoscale properties when the electric field orientations change. The results show that the direction of the electric field significantly affects the sign (positive or negative) of the dipole vector within the β-crystal lattice structure of the fibers. This can be attributed to the rotation of dipole vectors in response to the electric field–fiber alignment angle. Furthermore, the research identifies the crystal plane (201,111)β as exhibiting the highest magnitude of piezoelectric response strain in the β phase. The study also employs scanning electron microscopy and digital image correlation (DIC) to reveal the material's morphology and to assess fiber strain distribution at the micrometer scale under different voltages. DIC results particularly highlight that stress concentration leads to the deformation of fibers into voids, which are spaces between fibers created by electrospinning. This work comprehensively elucidates how deformation works in piezoelectric polymers by connecting large-scale changes observed in fibers through DIC and small-scale changes observed in WAXD studies presenting the piezoelectric strain responses at the crystal plane.

Effect of the electric field orientation on the thermal resistance of the solid–liquid interface

ABSTRACT With the rapid development of nanotechnology, using the applied electric field to regulate interfacial heat transfer has become increasingly important. In the present work, the relationship between the thermal resistance of Kapitza and the direction of the applied electric field is explored with nonequilibrium molecular dynamics method at a solid–liquid interface consisting of CU (0, 0, 1) and liquid water. It found that the electric field orientation induces the ordering of water molecules near the solid, which affects the magnitude of the Kapitza thermal resistance. In addition, the electric field orientation affects the degree of mismatch between solid and liquid vibrational dynamical density (VDOS), which affects the phonon transport at the solid–liquid interface, and ultimately affects the process of interfacial heat transfer. Furthermore, it’s found that there is a weak correlation between the interfacial thermal resistance and the dimension of the copper-water model.

Effect of electromagnetic radiation on the electronic and thermoelectric properties of armchair edge silicene nanoribbons

We theoretically investigate the influence of electromagnetic radiation on the electronic and thermoelectric properties of armchair edge silicene nanoribbons. Specifically, we study the effects of varying the polarization (s or p) and incident angle (0, 30, 45, 60, and 90°) of radiation on the band structure, transmission function, density of states, Seebeck coefficient, and electronic figure of merit (ZTe) of the nanoribbons. Our results demonstrate that the electronic properties are highly dependent on radiation conditions due to their influence on electron transport. We find that the transmission function and density of states exhibit distinct polarization-dependent behaviors that highlight the role of the radiation's electric field orientation. Importantly, the ZTe shows significant modulation with the incident angle for both polarizations, achieving optimized values up to 0.18. These findings provide insights into controlling the electronic and thermoelectric properties of silicene nanoribbons using electromagnetic radiation. Our work underscores opportunities for developing silicene-based nanophotonic devices with enhanced performance through all-optical means. The demonstrated tunability via irradiation paves the way for potential applications such as optical switches, sensors, and next-generation optoelectronics using silicene nanoribbons.

Catalytic divergencies in the mechanism of L-arginine hydroxylating nonheme iron enzymes.

Many enzymes in nature utilize a free arginine (L-Arg) amino acid to initiate the biosynthesis of natural products. Examples include nitric oxide synthases, which generate NO from L-Arg for blood pressure control, and various arginine hydroxylases involved in antibiotic biosynthesis. Among the groups of arginine hydroxylases, several enzymes utilize a nonheme iron(II) active site and let L-Arg react with dioxygen and α-ketoglutarate to perform either C3-hydroxylation, C4-hydroxylation, C5-hydroxylation, or C4-C5-desaturation. How these seemingly similar enzymes can react with high specificity and selectivity to form different products remains unknown. Over the past few years, our groups have investigated the mechanisms of L-Arg-activating nonheme iron dioxygenases, including the viomycin biosynthesis enzyme VioC, the naphthyridinomycin biosynthesis enzyme NapI, and the streptothricin biosynthesis enzyme OrfP, using computational approaches and applied molecular dynamics, quantum mechanics on cluster models, and quantum mechanics/molecular mechanics (QM/MM) approaches. These studies not only highlight the differences in substrate and oxidant binding and positioning but also emphasize on electronic and electrostatic differences in the substrate-binding pockets of the enzymes. In particular, due to charge differences in the active site structures, there are changes in the local electric field and electric dipole moment orientations that either strengthen or weaken specific substrate C-H bonds. The local field effects, therefore, influence and guide reaction selectivity and specificity and give the enzymes their unique reactivity patterns. Computational work using either QM/MM or density functional theory (DFT) on cluster models can provide valuable insights into catalytic reaction mechanisms and produce accurate and reliable data that can be used to engineer proteins and synthetic catalysts to perform novel reaction pathways.

Elasto-compliance of harmonically stimulated soft micro-gaps during electro-magneto-kinetic flows.

In this article, we develop and solve an analytical model to understand the elasto-hydrodynamic force response of a deformable, soft substrate, under dynamic loading; wherein the microfluidic gap between the substrate and load is subjected to electro-magneto-hydrodynamic interactions. As a simple physical system, we model the coupled fluid-structure-interaction characteristics when a rigid, small cylinder is permitted to impinge harmonically on an infinitely large elastic, soft substrate, and an oscillatory, squeeze flow establishes in the micro-gap formed between the two. We discuss the different observations and mechanics in terms of the governing Dukhin, Hartmann, and electroviscous numbers. The influence of electromagnetic stimuli on the flow, and its implications vis-à-vis the substrate compliance is the focus of the article. We reveal that for pure magnetohydrodynamics of the gap electrolyte, the transverse magnetic field and the induced streaming potential resist outward squeeze flow, thereby generating substantial amplifications in the force response. On the contrary, the effect of electro-magneto-hydrodynamics on the force response was strongly affected by the orientation and intensity of the transverse electric field. Notably, such variations depended significantly on the electrokinetic parameters, oscillation frequency, and substrate stiffness, whose effects were intertwined with the transverse and streaming potential electric fields. Further, possibilities of squeeze flow reversal due to opposing electromagnetic forces is observed, which may again modulate the compliance of the substrate in different mannerisms.

A Diamond Terahertz Large Aperture Photoconductive Antenna Biased by a Longitudinal Field

The novel design of a terahertz large aperture photoconductive antenna (LAPCA) is reported. It features a longitudinal orientation of the bias electric field within the photoconductive substrate, and has the advantage of a small interelectrode gap, resulting in a higher field for the same applied voltage. The proposed LAPCA configuration has been tested with a nitrogen-doped (∼10 ppm) synthetic monocrystalline diamond, which is a promising material for high-intensity and high-power terahertz sources. Two antennas with different high-voltage electrode realizations were assembled, pumped by a 400 nm femtosecond laser, and tested for THz emitter function. The experimental data are found to be in good correlation with the numerical simulation results. The performance of antennas with the conventional transverse E-field configuration and the novel longitudinal configuration is compared and discussed.

Microrobots powered by concentration polarization electrophoresis (CPEP)

Second-order electrokinetic flow around colloidal particles caused by concentration polarization electro-osmosis (CPEO) can result in a phoretic motion of asymmetric particle dimers in a homogeneous AC electrical field, which we refer to as concentration polarization electro-phoresis (CPEP). To demonstrate this actuation mechanism, we created particle dimers from micron-sized silica spheres with sizes 1.0 μm and 2.1 μm by connecting them with DNA linker molecules. The dimers can be steered along arbitrarily chosen paths within a 2D plane by controlling the orientation of the AC electric field in a fluidic chamber with the joystick of a gamepad. Further utilizing induced dipole-dipole interactions, we demonstrate that particle dimers can be used to controllably pick up monomeric particles and release them at any desired position, and also to assemble several particles into groups. Systematic experiments exploring the dependence of the dimer migration speed on the electric field strength, frequency, and buffer composition align with the theoretical framework of CPEO and provide parameter ranges for the operation of our microrobots. Furthermore, experiments with a variety of asymmetric particles, such as fragmented ceramic, borosilicate glass, acrylic glass, agarose gel, and ground coffee particles, as well as yeast cells, demonstrate that CPEP is a generic phenomenon that can be expected for all charged dielectric particles.

Mechanism of silicon-nanowire-diode orientation in DC electric fields

Doped semiconductor nanowires are emerging as next-generation electronic colloidal materials, and the efficient manipulation of such nanostructures is crucial for technological applications. In fluid suspension, pn nanowires (pn NWs), unlike homogeneous nanowires, have a permanent dipole, and thus, experience a torque under an external DC field that orients the nanowire with its n-type end in the direction of the field. Here, we quantitatively measure the permanent dipoles of various Si nanowire pn diodes and investigate their origin. By comparing the dipoles of pn NWs of different lengths and radii, we show that the permanent dipole originates from non-uniform surface-charge distributions, rather than the internal charges at the p–n junction as was previously proposed. This understanding of the mechanism for pn NWs orientation has relevance to the manipulation, assembly, characterization, and separation of nanowire electronics by electric fields.

Near-field diffraction of protons by a nanostructured metallic grating under external electric field: asymmetry and sidebands in Talbot self-imaging

Self-imaging in near-field diffraction is a practical application of coherent manipulation of matter waves in Talbot interferometry. In this work, near-field diffraction of protons by a nanostructured metallic grating under the influence of (a) uniform, (b) spatially modulated, and (c) temporally modulated electric fields are investigated. Time-domain simulations of two-dimensional Gaussian wave packets for protons are performed by solving the time-dependent Schrödinger’s equation using the generalized finite difference time domain method for quantum systems. Effects of strength (E 0) and orientation (θ) of the uniform electric field on the diffraction properties, such as fringe pattern, intensity of the peaks, fringe shift, and visibility, are investigated. The results show that the Talbot fringes shift significantly in the transverse direction even for a small change in the applied electric field ( V m−1) and its orientation (). Moreover, electric field-dependent fringe visibility is observed, which can be tuned by E 0 and θ. The potential barriers arising from a spatially modulated electric field are observed to cause significant distortions in the Talbot patterns when the modulation length () is equal to the de Broglie wavelength (). Sidebands are observed in the Talbot pattern due to the efficient transfer of energy from the oscillating field to the wave packet when the frequency of oscillation (ω) is of the order of ω 0 (), where T 0 is the interaction time. This study will be helpful in uniform electric field-controlled precision metrology, developing a highly sensitive electric field sensor based on Talbot interference, and precisely aligning the matter wave optical setup. Furthermore, the sidebands in the Talbot fringe can be used as a precise tool for momentum splitter in matter wave interferometry.

Coherent fluctuations in a partially magnetized small magnetron discharge operating on molecular nitrogen

We report experimental data on rotating plasma disturbances in a quasi-steady direct-current magnetron discharge operating with molecular nitrogen at pressures of 27, 40, 67, and 133 Pa. Experiments with a segmented anode measuring the local current flow reveal up to 12 coherent structures (“spokes”) propagating in the +E×B and −E×B azimuthal directions. The current–voltage characteristics are studied and found to follow a negative resistance profile at the lower discharge currents. The existence of coherent structures and the number of spokes observed depend on the discharge current and operating pressure. Lower pressures are more favorable to the retrograde −E×B spoke rotation, which is observed in the 27, 40, and 67 Pa discharges. The results are interpreted with a gradient-driven drift wave model, and using the dispersion relation, we show that the propagation direction depends on the orientation of the local electric field within the plasma. Using an electron fluid model, we show how experimental conditions can lead to field reversals that generate −E×B spoke rotation in the lower pressure discharges.

A Frequency Tunable Dielectric Resonator Antenna with Reduction of Cross Polarisation for Wi MAX and Sub 6 GHz 5G Applications

A frequency Tunable (mechanical tuning) Linearly Polarized (TLP) rectangular Dielectric Resonator Antenna(DRA) coupled with a horizontal/vertical-slot and excited with circular-ring type feed is investigated in this article.The frequency tunability (mechanical tuning) is achieved by the rotation of slot at different angles of the proposedstructure. Hence, two linearly polarized antennas have been proposed for different frequency bands such as Wi-MAX and Sub-6 GHz/5G, respectively, using slot variations (named as DRA-1 and DRA-2). TE 11δ mode has been excited in both the DRAs and confirmed by orientation of electric field inside the rectangular DRA. The measured -10 dB input impedance bandwidths of DRA-1 offer 21.60 % being centered at 2.87 GHz and the separation of co-polarized and cross-polarized field levels is above -24 dB in the broadside direction (xz-plane). Whereas DRA-2 offers measured -10 dB input impedance bandwidths of 23.03% being centered at 3.56 GHz having a separation of co-polarized and cross-polarized field levels are above -23 dB in the broadside direction (xz-plane). In addition, the proposed DRA-1 and DRA-2 show a maximum gain of 5.23 dBi and 4.75 dBi in broadside direction, respectively.

Effect of Interplay between Parallel and Perpendicular Magnetic and Electric Fields on Partial Discharges

This paper reports on the influence of a magnetic field on the dynamics of partial discharges (PDs) in two distinct configurations with respect to the mutual orientation of electric fields. The broad application areas include electrical insulation systems of both high-voltage grids and industrial network devices as well as emerging segments such as electric vehicles or more electric aircraft. Traditionally, PD measurements are only carried out in an electric field. In all current-carrying power equipment, magnetic fields are also superimposed onto electric ones, thus influencing partial discharge behavior. It has been observed that the interplay between electric and magnetic fields influences the dynamics of PDs; parallel and perpendicular mutual orientations were specifically investigated. The measurement technique allowed us to quantitively detect the effect of magnetic fields on PDs in a corona point–plane arrangement. The novel element presented in this article is a detection of PD intensity modulated by a magnetic field, with both perpendicular and parallel orientations with respect to electric one, and a quantitative visualization in the form of the time-sequence diagrams. The simulation of electron trajectories in the presence of electric and magnetic fields revealed the elongation of the pathways and differentiation of the charged particle propagation times. The perpendicularly oriented magnetic field led to a twisting effect, whereas the parallel alignment reflected the propagation along a helical trajectory. A slightly stronger PD intensity amplification effect was observed in the case of a parallel alignment of electric versus magnetic fields as compared with the perpendicular orientation. The presented results may contribute to PD measurement methodology in both electric and magnetic fields as well as a better understanding of the underlying physical mechanisms. The observed effect of the modulation of the magnetically based PD dynamics may be relevant for the insulation systems of power equipment.

A Multiscale Computational Model of Skeletal Muscle Electroporation Validated Using In Situ Porcine Experiments.

The goal of our study was to determine the importance of electric field orientation in an anisotropic muscle tissue for the extent of irreversible electroporation damage by means of an experimentally validated mathematical model. Electrical pulses were delivered to porcine skeletal muscle in vivo by inserting needle electrodes so that the electric field was applied in direction either parallel or perpendicular to the direction of the muscle fibres. Triphenyl tetrazolium chloride staining was used to determine the shape of the lesions. Next, we used a single cell model to determine the cell-level conductivity during electroporation, and then generalised the calculated conductivity changes to the bulk tissue. Finally, we compared the experimental lesions with the calculated field strength distributions using the Sørensen-Dice similarity coefficient to find the contours of the electric field strength threshold beyond which irreversible damage is thought to occur. Lesions in the parallel group were consistently smaller and narrower than lesions in the perpendicular group. The determined irreversible threshold of electroporation for the selected pulse protocol was 193.4 V/cm with a standard deviation of 42.1 V/cm, and was not dependent on field orientation. Muscle anisotropy is of significant importance when considering electric field distribution in electroporation applications. The paper presents an important advancement in building up from the current understanding of single cell electroporation to an in silico multiscale model of bulk muscle tissue. The model accounts for anisotropic electrical conductivity and has been validated through experiments in vivo.

Heterointerface construction for permalloy microparticles through the surface modification of bilayer metallic organic frameworks: Toward microwave absorption enhancement

Reasonable heterointerface modification can effectively regulate and enhance the microwave absorption of electromagnetic materials. The surface of magnetic permalloy (PM) microparticles is modified herein by coating double-layer metal organic frameworks (MOF), which are composed of a 2-methylimidazole cobalt salt (ZIF-67) layer and a 2-methylimidazole zinc salt (ZIF-8) layer. A stable heterointerface structure with cobalt/carbon (Co/C) and zinc/carbon (Zn/C) layers is formed on the surface of PM microparticles after pyrolysis. These particles include two types of composite particles of PM solely encapsulated by ZIF-67 or ZIF-8, PM@ZIF67 and PM@ZIF8, respectively, and two types of composite PM particles with a double-layered MOF outer shell structure obtained by exchanging the coating sequence (PM@ZIF8@ZIF67 and PM@ZIF67@ZIF8). Furthermore, the thermal decomposition temperature has a significant impact on the surface morphology and magnetic properties of the composite particles. After pyrolyzing at 500 °C, the PM@ZIF67@ZIF8 samples exhibit the highest microwave absorption performance among these samples. Specifically, the minimum reflection loss and effective absorption bandwidth of PM@ZIF67@ZIF8 after pyrolyzing at 500 °C can reach −47.3 dB at a matching thickness of 3.8 mm and 5.3 GHz at a matching thickness of 2.5 mm, respectively. A heterointerface with an electrical field orientation is created in the PM@ZIF67@ZIF8 particles, which effectively enhances the interface polarization and dipole polarization. Furthermore, the formation of a three-dimensional carbon network after pyrolysis is also useful for optimizing impedance matching and enhancing magneto-electric synergism.

Tailoring of the nonlinear optical rectification in vertically and laterally coupled InxGa1-xAs/GaAs quantum dots for Tera-hertz applications: Under In/Ga inter-diffusion, indium segregation, and strains effects

We numerically investigate the Nonlinear Optical Rectification (NOR) of two laterally coupled lens-shaped InxGa1-xAs/GaAs quantum dots and two layers of InxGa1-xAs/GaAs coupled QDs along the growth axis. In addition, we have examined the impact of applying an external electric field, hydrostatic pressure, and temperature on the NOR under indium segregation inside the wetting layer (WL) and In/Ga inter-diffusion in the QD region. The three-dimensional Schrödinger equation (3D) is solved numerically using the finite difference method (FDM) within the framework of the effective mass. We have used the compact density matrix formalism to compute the NOR coefficient. Our findings reveal that the indium segregation and inter-diffusion phenomena significantly affect the NOR coefficient and should be considered appropriately. It is also found that the lateral and vertical coupling thicknesses significantly impact the NOR coefficient, and the structure under investigation has a resonant behavior in the terahertz domain (0.1–10 THz). Moreover, obtained results reveal that the applied electric field orientation and intensity significantly affect the NOR magnitude. Therefore, the NOR intensity reaches the maximum value, χ(0)(2)=50.10-7m/V, for a negative applied electric field, F = −10 kV/cm. Additionally, it was shown that the increase in the hydrostatic pressure shifts the NOR spectrum to higher energies (blue-shift), whereas increasing temperature has the contrary effect. It is worth noting that the NOR magnitude and its attributed resonance energy can be adjusted for THz devices with a good choice of the external factors mentioned above.

Effects of pressure, temperature, and electric field on linear and nonlinear optical properties of InxGa1-xAs/GaAs strained quantum dots under indium segregation and In/Ga intermixing phenomena

Linear and nonlinear optical properties of InxGa1-xAs/GaAs lens-shaped quantum dots were investigated, taking into account simultaneous effects of indium segregation, In/Ga intermixing, temperature, pressure, external electric field, strains, and structure dimensions. Muraki's model was used for the indium segregation and a Gaussian distribution along the growth axis and radial direction for the atoms intermixing phenomenon. All simulations were carried out using the Finite Difference Method and the effective mass approximation. Nonlinear optical properties associated with refractive index changes and light absorption were evaluated and discussed on the basis of the calculated intersubband transition energies. The results showed that the mentioned parameters have a significant effect in controlling and tuning the nonlinear optical properties. It is shown that the indium segregation inside the wetting layer brought about a blue shift, whereas inhomogeneous indium distribution inside the QDs caused a red shift. Moreover, the nonlinear optical properties underwent a prominent stark-effect, and the resonant energy's red or blue shift is related to the electric field orientation. Furthermore, the nonlinear optical properties achieved a red (blue) shift with the increase in temperature (pressure). Thus, under the combined effects of the mentioned parameters, our theoretical results were correlated with the experimental data from photoluminescence spectra.

The shape-retention and heat-tolerant elastic helix based on azobenzene-polyimide supramolecular assembly

Helical structures are ubiquitous in natural and engineered systems across multiple length scales, while they often exhibit nearly uniform radius and pitch. Utilization of biomimetic structure design to develop stretchable and robust 3D helical structures that are shape-preserving and heat-tolerant is of great interest. Herein, we devise flexible 3D helixes by supramolecular self-assembly and high voltage electric field orientation of molecular chains. The 3D helixes not only inherit buffering mechanics with exceptional shape-retention ability against cyclic stretching but also exhibit excellent heat-resistant quality. The results of the experimental tests confirm that the helix can recover its original shape without obvious residual strain and basically withstand after 2000 cycles under force loading of 10 cN. Such robust biomimetic materials hold great prospects in the fields of artificial muscles, wearable materials, and so on.