Electrons In Layer Research Articles

Spiral RF carpet for ion mass spectrometry with radioactive isotope beams

A new type of Radio-Frequency carpet for ion trapping and transport, which is made of a small number of long electrodes wrapped together as parallel spirals, starting from the central ion extraction aperture, and extending outwards, is introduced as an alternative to the currently used concentric geometry. The main features introduced are the possibility to construct high electrode densities RF carpets which enhances the characteristics of such devices, by improving the collection efficiency, and a simpler design that eliminates the complex electronic layer from the carpet. The feasibility of the proposed novel spiral geometry for RF carpets is investigated using ion optics simulations.

Bilayer WSe2 as a natural platform for interlayer exciton condensates in the strong coupling limit.

Exciton condensates (ECs) are macroscopic coherent states arising from condensation of electron-hole pairs1. Bilayer heterostructures, consisting of two-dimensional electron and hole layers separated by a tunnel barrier, provide a versatile platform to realize and study ECs2-4. The tunnel barrier suppresses recombination, yielding long-lived excitons5-10. However, this separation also reduces interlayer Coulomb interactions, limiting the exciton binding strength. Here, we report the observation of ECs in naturally occurring 2H-stacked bilayer WSe2. In this system, the intrinsic spin-valley structure suppresses interlayer tunnelling even when the separation is reduced to the atomic limit, providing access to a previously unattainable regime of strong interlayer coupling. Using capacitance spectroscopy, we investigate magneto-ECs, formed when partially filled Landau levels couple between the layers. We find that the strong-coupling ECs show dramatically different behaviour compared with previous reports, including an unanticipated variation of EC robustness with the orbital number, and find evidence for a transition between two types of low-energy charged excitations. Our results provide a demonstration of tuning EC properties by varying the constituent single-particle wavefunctions.

In Tandem Contact‐Transfer Printing for High‐Performance Transient Electronics

AbstractHigh‐performance flexible electronics developed with resource efficient printing route will transform the way future electronics is manufactured and used to advance applications such as healthcare, Internet of Things, wearables, consumer electronics, etc. Herein, an innovative approach is presented that involves, for the first time, the in‐tandem use of contact and transfer printing methods to realize high‐quality electronic layers at selected locations on rigid (Si/SiO2), flexible (polyimide), and biodegradable (magnesium (Mg) foils). Superior grade quality of printed electronic layers is demonstrated by realizing transistors and printed UV photodetectors (PDs) employing high‐resolution electrohydrodynamic printing. The all‐printed PDs show extremely high performance for UV detection, with extraordinary high responsivity (>107 A W−1) and specific detectivity (≈1017 Jones) values at low UV intensity of 0.1 µW cm−2. Finally, the fabricated PDs on Mg foil are dissolved in deionized water at room temperature. Thus, in‐tandem contact and transfer printing has potential for ecofriendly development of transient electronics. Further, the approach allows printing of wide range of nanomaterials and heterostructures or complex superlattice structures, which can open exciting new possibilities for high‐performance electronics.

Electrically Switchable Film Structure of Conjugated Polymer Composites

Domains rich in different blend components phase-separate during deposition, creating a film morphology that determines the performance of active layers in organic electronics. However, morphological control either relies on additional fabrication steps or is limited to a small region where an external interaction is applied. Here, we show that different semiconductor-insulator polymer composites can be rapidly dip-coated with the film structure electrically switched between distinct morphologies during deposition guided by the meniscus formed between the stationary barrier and horizontally drawn solid substrate. Reversible and repeatable changes between the morphologies used in devices, e.g., lateral morphologies and stratified layers of semiconductors and insulators, or between phase-inverted droplet-like structures are manifested only for one polarity of the voltage applied across the meniscus as a rectangular pulse. This phenomenon points to a novel mechanism, related to voltage-induced doping and the doping-dependent solubility of the conjugated polymer, equivalent to an increased semiconductor content that controls the composite morphologies. This is effective only for the positively polarized substrate rather than the barrier, as the former entrains the nearby lower part of the coating solution that forms the final composite film. The mechanism, applied to the pristine semiconductor solution, results in an increased semiconductor deposition and 40-times higher film conductance.

Electrostatic shock waves driven by electron vortices in laser–plasma interactions

Nonlinear structures such as shock waves and vortices widely exist in nature and the Universe. They have also been separately observed in laser–plasma interactions. We show for the first time that two perpendicularly propagated collisionless electrostatic shock waves (CESs) can be excited by a moving electron vortex (EV). The latter is driven by an ultrashort intense laser pulse propagating through a sandwich nonuniform underdense plasma slab and is found to move perpendicularly to the density gradient. Two CESs are observed on both sides of the passing route of the EVs. The left-side CES is induced by a high-density electron layer, which originates from the vortex front and is compressed and accelerated during the EV motion. The right-side CES is induced by supersonic ions accelerated by the EVs directly. Ion acceleration by such CESs along the directions perpendicular to the vortex propagation is also observed. This study reveals the transformation of nonlinear structures and provides new routes for laser energy dissipation in plasmas.

Spatial Conflict Risk Measurement and Early Warning Based on Network Information Processing

The contradiction of land use is becoming more and more fierce in China, which poses a serious threat to the structural integrity and quantity of ecological land, the uncontrolled expansion of urban construction land, the imbalance between the spatial structure of agricultural land and ecological land, and the unreasonable spatial structure of various types of land within the city. This study mainly discusses the risk measurement and early warning of spatial conflict based on network information processing. In this study, GIS technology is used to deal with the risk of spatial conflict. Spatial conflict, in essence, is an objective geographical phenomenon arising from the competition for spatial resources in the process of human-land relations and is the result of the interaction between natural geographical factors and human factors, and natural geographical processes and human processes, and is a key factor affecting the sustainable development of the region. The logical network attack path composed of IP sequence captured by the space conflict network early warning and emergency response system is transformed into the attack path composed of a corresponding physical address sequence, which is directly displayed on the electronic map. At the same time, the attributes related to the spatial conflict events in the research area are also displayed in the form of a list. When the macro network early warning and emergency response system detect the occurrence of space conflict events in the study area, its emergency response subsystem queries the strategy database and outputs the emergency strategy in real-time by inputting the warning information analyzed by the early warning information analysis subsystem. Finally, the system realizes the functions of network node information visualization processing, network early warning and emergency response information visualization processing, and electronic layer basic operation. It is found that the industrial added value of the study area of ABC urban agglomeration has reached 283.140 billion yuan in recent three years, accounting for 60.25% of the industrial added value of the three cities and 30.98% of the whole province. The results show that the improper spatial regional combination has an important impact on the spatial conflict, and the improper spatial regional combination will significantly improve the level of spatial conflict.

Porous rare earth-transition metal bimetallic oxide nanoparticles oxygen electrocatalyst for rechargeable Zinc-air battery

BackgroundThe design and preparation of efficient nonprecious metal catalysts for the ORR, it is still a big challenge in alkaline media. Therefore, there is a need to develop an efficient electrocatalyst to meet the current problems such as energy scarcity in society MethodsIn this experiment, a series of bimetallic oxide nanoparticle catalysts (SmFeOx@CN) with fairly good morphology, which combine the advantages of rare earths and transition metal oxides, were successfully prepared by using silica dioxide as an encapsulated template and later removed. Significant findingsThe bimetallic oxide nanoparticle catalyst produces redox activity that is comparable to that of commercial platinum-carbon catalysts and shows excellent stability, power and energy densities. This excellent performance is owed to the concerted effect of bimetallic oxide nanoparticles and the special electronic layer structure of rare earths.

Tough, Instant, and Repeatable Adhesion of Self-Healable Elastomers to Diverse Soft and Hard Surfaces.

Repeatability and high adhesion toughness are usually contradictory for common polymer adhesives. Repeatability requires temporary interactions between the adhesive and the substrate, while high adhesion toughness is usually achieved by permanent bonding. Integrating these two features into one adhesive system is still a daunting challenge. Here, the development of a series of viscoelastic elastomers composed of a soft and hard segment is reported, which exhibit tough, instant, yet repeatable adhesion to a variety of soft and hard surfaces. Such a combination of mutually exclusive properties is attributed to the synergy of high mobility of polymer chains and massive viscoelastic dissipation of the elastomers around the interface. By optimizing the relaxation time and mechanical dissipation, the resulting adhesives can achieve a tough yet repeatable adhesion toughness above 2000 J m−2, superior to the best‐in‐class commercial adhesives. Numerous acrylate monomers are proven applicable to the preparation of such adhesives, validating the universality of the fabrication method. The application of these elastomers as adhesive and protective layers in soft electronics by virtue of their universal and tough adhesion to various soft and hard substrates is also demonstrated.

Magnetoplasmon-Polaritons in a Two-Dimensional Electron System with a Back Gate

Magnetoplasmon-polariton excitations in a two-dimensional (2D) electron system with a back gate are theoretically studied. The back gate is a metal layer that is parallel to the layer of 2D electrons and is separated from them by a dielectric substrate serving as a waveguide. In the absence of a magnetic field, the interaction of 2D plasmons with the modes of the waveguide limited by the gate from one side results in the formation of a family of waveguide plasmon-polariton modes. The two lowest of these modes are TM modes and have a gapless dispersion relation. As known, a static magnetic field B perpendicular to the plane of the system hybridizes different modes. The spectra and magnetodispersion of the found 2D modes are determined. The classification of all modes as longitudinal and transverse (ТМ–ТЕ classification), which is usually valid only in the absence of B, is recovered in the limit of high fields B. The magnetic field dependence of the cutoff frequencies of the considered modes significantly affects the results. Even a low magnetic field opens a frequency gap proportional to the magnetic field magnitude B in the spectrum of one of the lowest magnetoplasmon-polariton modes. As the magnetic field increases, the gap is saturated and the mode becomes waveguide.

Interpretation of Some Atomistic Concepts from the Characteristic Graph of the Atom

The study of the characteristic graph of an atom in all its aspects, allows to describe the concepts of atomistic. From this graph, some concepts of the recomposition of the electronic cloud have been described by specific graphs derived from it. The results are very conclusive. This graph illustrates each of the concepts of atomistics such as blocks, orders, periods and electronic layers. These concepts have been represented by lines, segments and even points. This has made it possible to draw up tables with orders, periods and even their correlations. Thus, this work promotes a better understanding of theoretical concepts by transposing the “abstract” aspect to a more “concrete” aspect of these concepts. This eventually facilitates the learning of this essential part of chemistry at its core. These results indicate that the research hypothesis has been verified.

Картографическое обеспечение идентификации природных и техногенных источников растворенного вещества в бассейне озера Байкал

A method of GIS mapping was developed to identify and assess the contributions of sources of matter to the composition of surface waters. The basis for the creation of the GIS database was the results of the study of the spatial diversity of the chemical composition of surface waters. Geoinformation analysis included the creation of a digital framework for mapping, vectorization of mapping sources and Earth remote sensing materials, creation of a single database combining cartographic, statistical information and field observation materials, morphometric relief analysis based on a digital relief model, creating a landscape basis for base maps, creating thematic maps, analyzing changes in the components of geosystems, creating electronic cartographic layers allowing to identify participation of solute sources in formation of water composition. The analysis of component changes was based on the results of different-time studies of the composition of water and bottom sediments. Based on the comparison of the chemical composition of the waters of the Baikal tributaries with the chemical and mineralogical composition of rocks, an approach was developed to identify sources of solute and assess their contributions to the formation of macro- and microelement compositions of surface waters. To solve the problems of the study, methods of statistical analysis of data, multicomponent mixing using systems of linear equations, field methods of data collection were used. Three main categories of solute sources (silicate, sulfide-containing silicate, carbonate rocks) were identified and their contributions to the chemical composition of water were calculated. On the basis of microelement tracers, the contributions of silicate rocks were divided into contributions of primary and secondary silicate rocks, ore-containing silicate rocks without sulfides were isolated. By comparing the ratios of concentrations of trace elements in the waters of uncontaminated territories and wastewater of enterprises, tracers were identified that made it possible to identify sources of surface water pollution. Maps of territories that determine a certain chemical composition of surface waters were compiled, which was first classified on the basis of the ratio of the contributions of drained rocks.

Способ очистки почвы и воды от тяжелых металлов и устройства для его осуществления

The work is based on the results of studies conducted on the effectiveness of the application for the purposeful transformation of the composition of harmful emissions by neutralizing the impurities included in them. And also researched and developed the process of cleaning and neutralizing the soil from heavy metals, by exposure to strong electric fields and discharges. The results of a quantitative analysis of soil samples taken from oil fields, bottom sediments of the Aras River cleaned before and after ordinary water are presented. According to the results, the content of heavy metals in the initial soils exceeds the maximum permissible concentration (MPC). The content of Mn, Mo, Cu, Al in the waters and bottom sediments of the Aras River also exceeds the MPC. The possibility of cleaning the soil from a certain name of heavy metals by exposure to ozone water has been revealed. Experiments on soil and water ozonation at voltages of 8 kV and 14 kV for 30 minutes showed a significant decrease in the concentration of heavy metals. The results of cleaning soil samples before and after treatment with ozonated water were checked with an inductively coupled plasma mass spectrometer.мThe process of chemical oxidation of pollutants in soils, soils, underground and surface waters is based on the release of electrons from the outer unstable layer of the electron shell of atoms of substances and elements, which leads to the transition of the pollutant into a less toxic and reactive form. Atoms of elements that have a small number of electrons in the outer electron layer tend to give up electrons. The process is an integral part of the redox interaction between the contaminant and the chemical or reactive surface.

Electron relay acceleration in wakefields driven by a single laser interacting with multi-stage plasma channels

One limitation in high energy and high-efficiency electron acceleration by laser-driven plasma wakefield is the dephasing due to the accelerated electrons surpassing the acceleration phase of the wake. Here, by utilizing multi-stage plasma channels with different densities, we show in simulations that electrons can jump from a back acceleration bubble into a front one before getting into the deceleration phase and obtain relay acceleration in the front bubble when the laser steps into a new stage of the plasma channel. In our numerical studies, the final maximum energy of the electrons by such relay acceleration can be several times higher than electrons accelerated in a single-stage plasma channel. The defocusing effects on the beam emittance and charge, caused by electrons crossing the high-density electron layer located between the neighboring bubbles, can be suppressed by appropriately connecting the staged channels. The current scheme helps to increase the acceleration energy and efficiency of laser wakefield accelerators.

Stable freestanding two-dimensional anionic electrons in YCl with extremely weak interlayer interaction

The 2D vdW electride material YCl with a halogen-metal-halogen sandwich-like structure has been demonstrated for the first time to exhibit weak interlayer interactions as well as to have a stable anionic electron layer encapsulated within layers.

Development of a Low-Cost System for 3D Orchard Mapping Integrating UGV and LiDAR.

Growing evaluation in the early stages of crop development can be critical to eventual yield. Point clouds have been used for this purpose in tasks such as detection, characterization, phenotyping, and prediction on different crops with terrestrial mapping platforms based on laser scanning. 3D model generation requires the use of specialized measurement equipment, which limits access to this technology because of their complex and high cost, both hardware elements and data processing software. An unmanned 3D reconstruction mapping system of orchards or small crops has been developed to support the determination of morphological indices, allowing the individual calculation of the height and radius of the canopy of the trees to monitor plant growth. This paper presents the details on each development stage of a low-cost mapping system which integrates an Unmanned Ground Vehicle UGV and a 2D LiDAR to generate 3D point clouds. The sensing system for the data collection was developed from the design in mechanical, electronic, control, and software layers. The validation test was carried out on a citrus crop section by a comparison of distance and canopy height values obtained from our generated point cloud concerning the reference values obtained with a photogrammetry method. A 3D crop map was generated to provide a graphical view of the density of tree canopies in different sections which led to the determination of individual plant characteristics using a Python-assisted tool. Field evaluation results showed plant individual tree height and crown diameter with a root mean square error of around 30.8 and 45.7 cm between point cloud data and reference values.

Classification accuracy improvement of the optical diffractive deep neural network by employing a knowledge distillation and stochastic gradient descent β-Lasso joint training framework

Optical diffractive deep neural network (OD2NN) is an optical machine learning framework that utilizes diffraction on the cascaded diffractive surfaces to perform an arbitrary function. Compared with the deep neural networks (DNNs) implemented in electronic domain, proof-of-principle demonstrations of OD2NNs show promising advantages in terms of speed and power efficiency. However, the classification accuracy of the demonstrated OD2NN has been limited by the absence of optical nonlinear operations, even in the hybrid OD2NNs which are integrated with electronic neural networks. Here, we propose a novel training framework to improve the classification accuracy of the OD2NNs without employing any nonlinear physical elements. In this framework, the hybrid OD2NN with a fully connected electronic layer integrated (hybrid) are preferred and knowledge distillation (KD) and stochastic gradient descent β-Lasso (SGD-β-Lasso) joint-training are used. A blind testing classification accuracy of 70.19% and 85.17% have been obtained for Cifar-10 and Cats vs. Dogs dataset, respectively, which is the state-of-the-art accuracy achieved by the hybrid OD2NN so far. In addition, the proposed framework can significantly reduce the complexity of hardware fabrication and layers alignment since the hybrid OD2NN only consists of 5 diffractive layers. This work take a big step forward the application of the OD2NN in realistic scenarios.

Assessment and Application of Modified Cationic Polyvinyl Alcohol Emulsifiers in Bitumen Emulsions

Abstract In this work, a series of emulsifiers were prepared by changing the molar ratio of polyvinyl alcohol (PVA) to the long chain quaternary ammonium salt (A0). The emulsifiers were characterised by FTIR and 1HNMR. The stability of the emulsions was checked and evaluated by determining the phase separation and by UV-Vis spectrophotometry. The emulsion stability increased with increasing emulsifier concentration, which was mainly due to the reduced droplet size and increased viscosity of the emulsions. Stability was also dependent on pH. At pH values between 5 to 3, stability was increased, but at further decreasing pH values, the emulsion became unstable or the emulsion separated. This could be mainly because the excess of positive ions compresses the double electron layer. The experimental results showed that PVA as a macromolecular matrix material has a great application potential for the emulsification process.

Phase-Field Simulation of Liquid-Vapor Equilibrium and Evaporation of Fluid Mixtures.

In solution processing of thin films, the material layer is deposited from a solution composed of several solutes and solvents. The final morphology and hence the properties of the film often depend on the time needed for the evaporation of the solvents. This is typically the case for organic photoactive or electronic layers. Therefore, it is important to be able to predict the evaporation kinetics of such mixtures. We propose here a new phase-field model for the simulation of evaporating fluid mixtures and simulate their evaporation kinetics. Similar to the Hertz-Knudsen theory, the local liquid-vapor (LV) equilibrium is assumed to be reached at the film surface and evaporation is driven by diffusion away from this gas layer. In the situation where the evaporation is purely driven by the LV equilibrium, the simulations match the behavior expected theoretically from the free energy: for evaporation of pure solvents, the evaporation rate is constant and proportional to the vapor pressure. For mixtures, the evaporation rate is in general strongly time-dependent because of the changing composition of the film. Nevertheless, for highly nonideal mixtures, such as poorly compatible fluids or polymer solutions, the evaporation rate becomes almost constant in the limit of low Biot numbers. The results of the simulation have been successfully compared to experiments on a polystyrene-toluene mixture. The model allows to take into account deformations of the liquid-vapor interface and, therefore, to simulate film roughness or dewetting.

Light Directs Monomer Coordination in Catalyst-Free Grignard Photopolymerization.

π-Conjugated polymers can serve as active layers in flexible and lightweight electronics and are conventionally synthesized by transition-metal-mediated polycondensation at elevated temperatures. We recently reported a photopolymerization of electron-deficient heteroaryl Grignard monomers that enables the catalyst-free synthesis of n-type π-conjugated polymers. Herein, we describe an experimental and computational investigation into the mechanism of this photopolymerization. Spectroscopic studies performed in situ and after quenching reveal that the propagating chain is a radical anion with halide end groups. DFT calculations for model oligomers suggest a Mg-templated SRN1-type coupling, in which Grignard monomer coordination to the radical anion chain avoids the formation of free sp2 radicals and allows C-C bond formation with very low barriers. We find that light plays an unusual role in the reaction, photoexciting the radical anion chain to shift electron density to the termini and thus enabling productive monomer binding.

Accelerating charge transfer via nonconjugated polyelectrolyte interlayers toward efficient versatile photoredox catalysis

One of the challenges for high-efficiency single-component-based photoredox catalysts is the low charge transfer and extraction due to the high recombination rate. Here, we demonstrate a strategy to precisely control the charge separation and transport efficiency of the catalytic host by introducing electron or hole extraction interlayers to improve the catalytic efficiency. We use simple and easily available non-conjugated polyelectrolytes (NCPs) (i.e., polyethyleneimine, PEI; poly(allylamine hydrochloride), PAH) to form interlayers, wherein such NCPs consist of the nonconjugated backbone with charge transporting functional groups. Taking CdS as examples, it is shown that although PEI and PAH are insulators and therefore do not have the ability to conduct electricity, they can form good electron or hole transport extraction layers due to the higher charge-transfer kinetics of pendant groups along the backbones, thereby greatly improving the charge transfer capability of CdS. Consequently, the resultant PEI-/PAH-functionalized nanocomposites exhibit significantly enhanced and versatile photoredox catalysis.