Continuous Electron Research Articles

Simulation and experimental study on a high figure of merit LDMOS with ingenious layout design

To improve the tradeoff relationship between the specific on-resistance (R on,sp) and breakdown voltage (BV), a novel lateral double-diffusion metal-oxide-semiconductor field effect transistor (LDMOSFET) with an ingenious layout design is proposed and investigated by simulations and experiments. The proposed LDMOS features a specific convex-shape field plate (CFP) structure at source side and two separated integrated diodes (SID) at the drain side. On one hand, a continuous electron accumulation layer is formed from source to drain in the on-state, providing an ultralow current path to decrease the R on,sp. On the other hand, the CFP and SID structures allow the proposed device to make full use of the drift length to sustain the off-state voltage, so that the novel device could maintain the same BV level with a shortened drift length. Thus, the proposed CFP–SID LDMOS achieves a much lower R on,sp and better R on,sp–BV tradeoff relationship. The experimental results illustrate that the CFP–SID LDMOS realizes a BV of 518 V and R on,sp of 23.5 mΩ·cm2 with a high figure of merit (FOM) of 11.42 MW cm−2. Compared with the triple-RESURF LDMOS under the same BV, the proposed device decreases the R on,sp by 53.8%.

3D CoMoO4 nanoflake arrays decorated disposable pencil graphite electrode for selective and sensitive enzyme-less electrochemical glucose sensors.

Three-dimensional (3D) cobalt molybdate (CoMoO4) hierarchical nanoflake arrays on pencil graphite electrode (PGE) (CoMoO4/PGE) are actualized via one-pot hydrothermal technique. The morphological features comprehend that the CoMoO4 nanoflake arrays expose the 3D, open, porous, and interconnected network architectures on PGE. The formation and growth mechanisms of CoMoO4 nanostructures on PGE are supported with differentstructural and morphological characterizations. The constructed CoMoO4/PGE is operated as an electrocatalytic probe in enzyme-less electrochemical glucose sensor (ELEGS), confronting the impairments of cost- and time-obsessed conventional electrode polishing and catalyst amendment progressions and obliged the employment of a non-conducting binder. The wide-opened interior and exterior architectures of CoMoO4 nanoflake arrays escalate the glucose utilization efficacy, whilst the intertwined nanoflakes and graphitic carbon layers, respectively, of CoMoO4 and PGE articulate the continual electron mobility and catalytically active channels of CoMoO4/PGE. It jointly escalates the ELEGS concerts of CoMoO4/PGE including high sensitivity (1613 μA mM-1cm-2), wide linear glucose range (0.0003-10mM), and low detection limit (0.12µM) at a working potential of 0.65V (vs. Ag/AgCl) together with the good recovery in human serum. Thus, the fabricated CoMoO4/PGE extends exclusive virtues of modest electrode production, virtuous affinity, swift response, and excellent sensitivity and selectivity, exposing innovative prospects to reconnoitring the economically viable ELEGSs with binder-free, affordable cost, and expansible 3D electrocatalytic probes.

Evidence of Au(II) and Au(0) States in Bovine Serum Albumin-Au Nanoclusters Revealed by CW-EPR/LEPR and Peculiarities in HR-TEM/STEM Imaging.

Bovine serum albumin-embedded Au nanoclusters (BSA-AuNCs) are thoroughly probed by continuous wave electron paramagnetic resonance (CW-EPR), light-induced EPR (LEPR), and sequences of microscopic investigations performed via high-resolution transmission electron microscopy (HR-TEM), scanning transmission electron microscopy (STEM), and energy dispersive X-ray analysis (EDS). To the best of our knowledge, this is the first report analyzing the BSA-AuNCs by CW-EPR/LEPR technique. Besides the presence of Au(0) and Au(I) oxidation states in BSA-AuNCs, the authors observe a significant amount of Au(II), which may result from a disproportionation event occurring within NCs: 2Au(I) → Au(II) + Au(0). Based on the LEPR experiments, and by comparing the behavior of BSA versus BSA-AuNCs under UV light irradiation (at 325 nm) during light off-on-off cycles, any energy and/or charge transfer event occurring between BSA and AuNCs during photoexcitation can be excluded. According to CW-EPR results, the Au nano assemblies within BSA-AuNCs are estimated to contain 6–8 Au units per fluorescent cluster. Direct observation of BSA-AuNCs by STEM and HR-TEM techniques confirms the presence of such diameters of gold nanoclusters in BSA-AuNCs. Moreover, in situ formation and migration of Au nanostructures are observed and evidenced after application of either a focused electron beam from HR-TEM, or an X-ray from EDS experiments.

Hierarchically Structured Conductive Polymer Binders with Silver Nanowires for High-Performance Silicon Anodes in Lithium-Ion Batteries.

Silicon (Si) anodes in lithium-ion batteries (LIBs) suffer from huge volume changes that lead to a rapid capacity decrease and short cycle life. A conductive binder can be a key factor to overcome this issue, maintaining continuous electron paths under pulverization of Si. Herein, composites of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and poly(vinyl alcohol) (PVA) are augmented with poly(ethylene glycol) (PEG) and poly(ethylene oxide) (PEO) as a binder for Si anodes, which forms hierarchical structures due to different chain lengths of PEG and PEO. The integration of PEG and PEO imparts higher electrical conductivity (∼40%) and stretchability (∼60%) through densely spread hydrogen bonding and cross-linking, compared to conductive polymer binders with PEO or PEG. Further, a silver nanowire (AgNW) network combined with the polymer binder supplies an effective three-dimensional (3D) electrical path, sufficient void space to buffer the volume changes, and highly adhesive interaction with the current collector. The fabricated Si anode demonstrates a higher specific capacity of 1066 mAh g-1 at 0.8 A g-1 after 100 cycles and improved rate capability.

Development of a direct-sampling RF receiver for precision beam charge measurements in the MOLLER experiment

We have developed and tested a direct-sampling RF receiver capable of measuring the amplitude of a 1497 MHz sinusoidal beam signal in 0.5 ms integration windows with a relative uncertainty of better than 10 parts per million. The receiver is intended for measuring signals from beam current monitoring cavities on the beamline of the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. The beam signal strength, frequency, and integration window fulfill the thus far unmet requirements of the upcoming MOLLER experiment to measure the beam charge for different helicity states.

Two-dimensional recurrence relations and Takagi–Taupin equations. I. Dynamical X-ray diffraction by a perfect crystal

The dynamical diffraction of spatially restricted X-ray beams in a thick perfect crystal is studied using two-dimensional recurrence relations and the Takagi–Taupin (T-T) equations. It is shown that the two-dimensional recurrence relations are transformed into T-T equations when passing from a crystal with an array of discrete lattice planes to a model of continuous periodic electron density. The results of calculations of the X-ray diffraction field inside the crystal and the angular distribution of the scattering intensity in reciprocal space based on these two approaches are presented. It is shown that, when using the two-dimensional recurrence relations and T-T equations, the calculated contours of reciprocal-space maps and their qx sections are similar to each other, and the qz sections completely coincide.

Magnetostructural Dependencies in 3d2Systems: The Trigonal Bipyramidal V3+Complex

We introduce a multiconfigurational approach to study the magnetostructural correlations in systems. The theoretical framework represents a restricted active space self‐consistent field method, with active space optimized to the number of all non‐bonding orbitals. To demonstrate the validity and effectiveness of the method, we explore the physical properties of the trigonal bipyramidal spin‐one single‐ion magnet . The obtained theoretical results show good agreement with the experimental data available in the literature. This includes measurements for the magnetization, low‐field susceptibility, continuous wave electron paramagnetic resonance, and photoluminescence spectroscopy. The proposed method may be reliably applied to a variety of magnetic systems. To this end, and for the sake completeness, we provide detailed analytical and numerical representations for the generic Hamiltonian's effective matrix elements related to the crystal field, exchange, spin–orbit, and Zeeman interactions.

Electron Heat Source Driven Heat Transport in GaN at Nanoscale: Electron-Phonon Monte Carlo Simulations and a Two Temperature Model.

The thermal energy transport in semiconductors is mostly determined by phonon transport. However in polar semiconductors like GaN electronic contribution to the thermal transport is non-negligible. In this paper, we use an electron–phonon Monte Carlo (MC) method to study temperature distribution and thermal properties in a two-dimensional GaN computational domain with a localized, steady and continuous electron heat source at one end. Overall, the domain mimics the two-dimensional electron gas (2DEG) channel of a typical GaN high electron mobility transistor (HEMT). High energy electrons entering the domain from the source interact with the phonons, and drift under the influence of an external electric field. Cases of the electric field being uniform and non-uniform are investigated separately. A two step/temperature analytical model is proposed to describe the electron as well as phonon temperature profiles and solved using the finite difference method (FDM). The FDM results are compared with the MC results and found to be in good agreement.

Electrocatalytic Perchlorate Reduction Using an Oxorhenium Complex Supported on a Ti4O7 Reactive Electrochemical Membrane.

An organometallic rhenium catalyst was deposited on a Ti4O7 reactive electrochemical membrane (Re/REM) for the electrocatalytic reduction of aqueous ClO4- to Cl-. Results showed increasing ClO4- reduction upon increasing cathodic potential (i.e., -0.4 to-1.7 V/SHE). A 5 mM ClO4- solution was reduced by ∼21% in a single pass (residence time ∼0.2 s) through the Re/REM at a pH of 7, with >99% Cl- selectivity and a current efficiency of ∼100%. Kinetic analysis indicated that the reaction rate constant increased from 3953 to 7128 L h-1 gRe-1 at pH values of 9 to 3, respectively, and was mass transport-limited at pH < 5. The rate constants were 2 orders of magnitude greater than reported values for an analogous catalytic system using hydrogen as an electron donor. A continuous flow Re/REM system reduced 1 ppm ClO4- in a groundwater sample by >99.9% for the first 93.5 h, and concentrations were lower than the EPA ClO4- guideline (56 ppb) for 374 h of treatment. The fast ClO4- reduction kinetics and high chloride selectivity without the need for acidic conditions and a continual hydrogen electron donor supply for catalyst regeneration indicate the promising ability of the Re/REM for aqueous electrocatalytic ClO4- treatment.

Accurate structure determination of nanocrystals by continuous precession electron diffraction tomography

三维电子衍射已逐渐成为人们探索微观世界的强有力的工具. 本文中, 我们展示了一种新的三维电子衍射数据收集方法, 命名为连续 旋转旋进电子衍射断层扫描(cPEDT), 该方法是旋进电子衍射断层扫描 (PEDT)与连续旋转电子衍射(cRED)的结合. 使用cPEDT方法, 可以避 免PEDT方法中步进式过程引入的不必要的电子剂量, 同时利用cPEDT 收集到的数据也可以进行动力学精修从而确定材料的精确结构. 该方 法可以促进三维电子衍射在一些电子束敏感材料上的应用, 如金属-有 机框架(MOF)、共价有机框架(COF), 以及一些有机物.

Bimetallic metal-organic framework derived 3D hierarchical NiO/Co3O4/C hollow microspheres on biodegradable garbage bag for sensitive, selective, and flexible enzyme-free electrochemical glucose detection

Hierarchical NiO/Co 3 O 4 /C hollow architectures acquired from metal organic frameworks on biodegradable corn starch bag is exploited as a binder less and flexible electrochemical probe for high performance enzyme-fee glucose sensor. • NiO/Co 3 O 4 /C hollow architectures were prepared using Ni-Co/MOF sacrificial templates. • Impacts of catalyst’s molecular/electronic structures on GEOR are realized with DFT. • Ni 3+ /Co 4+ centres involved glucose electrooxidation mechanism is validated. • NiO/Co 3 O 4 /C/BCSB demonstrated sensitive, selective and flexible glucose detection. • NiO/Co 3 O 4 /C’s competence in real sample glucose sensing is realized with human serum. The hierarchical hollow architectured NiO/Co 3 O 4 /C is developed using the sacrificial template of Ni-Co MOF and the proximity of Ni(II)/Co(II) ions with organic ligand in Ni-Co MOF accelerates the generation of tightly pinned NiO/Co 3 O 4 nanostructures with carbon. The elevated charge-transfer process among the constituents of as-formulated nanocatalysts and their structural and electronic relationship are established with DFT studies. The hollow architecture of NiO/Co 3 O 4 /C exposes both the inner and outer surfaces for an effectual glucose utilization, whilst the carbon interlaced metal nanoparticles and binary metal oxide synergism enumerate, respectively, the continual electron mobility and catalytically active channels, accelerating NiO/Co 3 O 4 /C loaded Biodegradable corn starch bag’s (BCSB) enzyme-free glucose sensing performance in human serum with high sensitivity and selectivity. The consistent flexible glucose electrooxidation acquired for NiO/Co 3 O 4 /C/BCSB under variant bending angles along with other unique concerts establish the bendable, binder-less, stable, reusable, and eco-friendly electrochemical probes for the evolution of revolutionary electrochemical diagnosis devices.

ELF/VLF Wave Radiation Experiment by Modulated Ionospheric Heating Based on Multi-Source Observations at EISCAT

Ground-based high-frequency modulated waves can periodically heat the ionosphere and create “virtual antennas”, which can radiate extremely low frequency (ELF, 0.3–3 kHz) or very low frequency (VLF, 3–30 kHz) waves for long-distance communication. Ionospheric X-mode and O-mode heating experiments using amplitude and beat-wave (BW) modulations were conducted on 21 November 2019. Experimental results were analyzed from multiple perspectives based on data from Dynasonde, a magnetometer, stimulated electromagnetic emissions, an ELF/VLF signal receiver, and ultra-high-frequency radar. The strongest excited ELF/VLF signals in previous BW modulation heating experiments were around 8–12 kHz; however, in this experiment, no signal excited in this frequency range was observed, and the signal with the highest signal/noise ratio was at the frequency of 3517 Hz, which will aid in understanding the best communication frequency under different ionospheric backgrounds. It is well-accepted that the electron temperature changes periodically with the modulation frequency. However, we noted that the electron temperature had insufficient cooling during the O-mode modulated heating process and then increased again, resulting in a continuous electron temperature increase. We found that this was related to the change in ion composition after analyzing ion-line spectra, which will be helpful in studying the effect of modulation heating on the ionosphere background.

CW-EPR spectra of P1 centers in HPHT diamond in the vicinity of Rabi resonance: possible standard for [formula omitted] evaluation in EPR and DNP enhanced NMR spectroscopies

Synthetic commercial type-IIa diamond crystal containing low concentration of P1 (Ns0) centers ([Ns0] <1ppm) was examined as a possible calibration standard for evaluating microwave magnetic field intensity (B1) in the spectrometer cavity. The reliability of this standard was experimentally and theoretically tested by employing two different types of microwave cavities with different distributions of B1 values. The procedure relies on the ordinary continuous wave electron paramagnetic resonance (CW-EPR) with magnetic field modulation (ωrf/2π=100 kHz) applied under the regime of the microwave power (PMW) saturation of the out-of-phase first harmonic signal. The power saturation procedure for PMW∼B11/2 was analyzed with respect to the change of spectral lineshape when Rabi frequency (ω1=γB1, γis the electron gyromagnetic ratio) approaches to ωrf. The phenomenon of the inversion of sideband lines while passing the Rabi resonance condition (ω1=ωrf) was analyzed. In specific, from the simulation of the experimental lineshapes in the close vicinity of Rabi resonance (ω1≈ωrf) the correspondingB1 can be assigned. For the chosen diamond crystal low value of B1≈3.6µT at Rabi resonance was determined what makes it a convenient standard for DNP enhanced NMR spectroscopy which requires relatively small B1.

Deep Learning Based Superconducting Radio-Frequency Cavity Fault Classification at Jefferson Laboratory.

This work investigates the efficacy of deep learning (DL) for classifying C100 superconducting radio-frequency (SRF) cavity faults in the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. CEBAF is a large, high-power continuous wave recirculating linac that utilizes 418 SRF cavities to accelerate electrons up to 12 GeV. Recent upgrades to CEBAF include installation of 11 new cryomodules (88 cavities) equipped with a low-level RF system that records RF time-series data from each cavity at the onset of an RF failure. Typically, subject matter experts (SME) analyze this data to determine the fault type and identify the cavity of origin. This information is subsequently utilized to identify failure trends and to implement corrective measures on the offending cavity. Manual inspection of large-scale, time-series data, generated by frequent system failures is tedious and time consuming, and thereby motivates the use of machine learning (ML) to automate the task. This study extends work on a previously developed system based on traditional ML methods (Tennant and Carpenter and Powers and Shabalina Solopova and Vidyaratne and Iftekharuddin, Phys. Rev. Accel. Beams, 2020, 23, 114601), and investigates the effectiveness of deep learning approaches. The transition to a DL model is driven by the goal of developing a system with sufficiently fast inference that it could be used to predict a fault event and take actionable information before the onset (on the order of a few hundred milliseconds). Because features are learned, rather than explicitly computed, DL offers a potential advantage over traditional ML. Specifically, two seminal DL architecture types are explored: deep recurrent neural networks (RNN) and deep convolutional neural networks (CNN). We provide a detailed analysis on the performance of individual models using an RF waveform dataset built from past operational runs of CEBAF. In particular, the performance of RNN models incorporating long short-term memory (LSTM) are analyzed along with the CNN performance. Furthermore, comparing these DL models with a state-of-the-art fault ML model shows that DL architectures obtain similar performance for cavity identification, do not perform quite as well for fault classification, but provide an advantage in inference speed.

Quantifying the Number and Affinity of Mn2+-Binding Sites with EPR Spectroscopy.

During the last decades, various functional oligonucleotides have been discovered including DNAzymes, ribozymes, and riboswitches. Their function is based on their ability to form and change their three-dimensional structure. Binding of divalent ions to specific binding pockets was found to be important for the global structure and function. Here, we present a protocol that allows counting the number of Mn2+-binding sites and to determine their dissociation constants by means of continuous wave X-band Electron Paramagnetic Resonance (EPR) spectroscopy. In this method, Mn2+ is titrated into the oligonucleotide-containing sample and the intensity of the EPR spectrum is recorded. By comparison with a Mn2+-only reference sample, the binding isotherm can be constructed and fitted to binding models yielding the number and affinities of the binding sites. This method has been successfully applied to several functional oligonucleotides.

Gas sorption properties and kinetics of porous bismuth-based metal-organic frameworks and the selective CO2 and SF6 sorption on a new bismuth trimesate-based structure UU-200

Bismuth-based metal-organic frameworks (Bi-MOFs) such as bismuth subgallate are important for applications ranging from medicine to gas separation and catalysis. Due to the porous nature of such Bi-MOFs, it would be valuable to understand their gas sorption and separation properties. Here, we present the gas sorption properties of three microporous Bi-MOFs, namely, CAU-17, CAU-33, and SU-101, along with a new trimesate-based structure, UU-200. We perform a detailed analysis of the sorption properties and kinetics of these Bi-MOFs. UU-200 shows good uptake capacities for CO 2 (45.81 cm 3 g −1 STP) and SF 6 (24.69 cm 3 g −1 STP) with CO 2 /N 2 and SF 6 /N 2 selectivities over 35 and 44, respectively at 293 K, 100 kPa. The structure of UU-200 is investigated using continuous rotation electron diffraction and is found to be a 3D porous framework containing pores with a diameter of 3.4–3.5 Å. Bi-MOFs as a group of relatively under-investigated types of MOFs have interesting sorption properties that render them promising for greenhouse gas adsorbents with good gas uptake capacities and high selectivities. • Synthesis of a new permanently porous trimesate-based bismuth metal-organic framework (MOF). • High uptake capacity and selectivity for CO 2 and SF 6 of UU-200 was comparable to other Bi-MOFs. • Rate-limiting mechanisms for CO 2 adsorption were found to likely be governed by film diffusion and micropore diffusion.

Ионно-плазменное травление, инициированное электронным пучком

The etching of quartz sample by the flow of energetic ions from the beam plasma produced by continuous electron beam injected in a dielectric cavity in argon in medium vacuum (2.7 Pa) was demonstrated. The energy of bombarding ions was adjusted by the voltage drop on a sheath between a plasma boundary and the cavity bottom charging by the electron beam, so the beam was the only source of generating ions and adjusting their energy. It was found that the etching rate grows with the electron beam energy following the increase in the absolute value of the near-bottom voltage drop.

Ternary organic photovoltaics with good thickness tolerance by NC70BA as the third component

In this work, thin (100 nm) and thick-film (150 nm and 200 nm) ternary organic photovoltaics (OPVs) were fabricated by introducing NC 70 BA into PTQ10:Y11 films. NC 70 BA enhances the charge carrier mobility and suppresses charge recombination in the ternary photoactive layers. This improved the highest photovoltaic performance under a thinner photoactive layer and reduced the decrease ratio under a thicker photoactive layer for optimized ternary OPVs relative to PTQ10:Y11 binary OPVs. The 3D hollow spherical structure of NC 70 BA forms continuous electron transport channels, which enhance the charge carrier mobility capability and relatively thickness-insensitive photovoltaic performance of optimized ternary OPVs compared with those of PTQ10:Y11 binary OPVs. Our results demonstrate the feasibility of employing the fullerene derivative NC 70 BA as a third component material and PTQ10:Y11 as a host binary film to construct high-efficiency thickness-insensitive ternary OPVs; this approach would promote the development of thicker photoactive layer ternary OPVs to fulfil the requirements of solution coating processes. • The ternary OPV with blend acceptor achieved a PCE of 14.96%. • Around 10% PCE improvement is obtained by employing ternary strategy. • The improvement of exciton dissociation at the PTQ10/NC 70 BA/Y11 interface. • The enhancement of photon harvesting by the blend acceptor of NC 70 BA and Y11.

Integrated photonics enables continuous-beam electron phase modulation

Integrated photonics facilitates extensive control over fundamental light–matter interactions in manifold quantum systems including atoms1, trapped ions2,3, quantum dots4 and defect centres5. Ultrafast electron microscopy has recently made free-electron beams the subject of laser-based quantum manipulation and characterization6–11, enabling the observation of free-electron quantum walks12–14, attosecond electron pulses10,15–17 and holographic electromagnetic imaging18. Chip-based photonics19,20 promises unique applications in nanoscale quantum control and sensing but remains to be realized in electron microscopy. Here we merge integrated photonics with electron microscopy, demonstrating coherent phase modulation of a continuous electron beam using a silicon nitride microresonator. The high-finesse (Q0 ≈ 106) cavity enhancement and a waveguide designed for phase matching lead to efficient electron–light scattering at extremely low, continuous-wave optical powers. Specifically, we fully deplete the initial electron state at a cavity-coupled power of only 5.35 microwatts and generate >500 electron energy sidebands for several milliwatts. Moreover, we probe unidirectional intracavity fields with microelectronvolt resolution in electron-energy-gain spectroscopy21. The fibre-coupled photonic structures feature single-optical-mode electron–light interaction with full control over the input and output light. This approach establishes a versatile and highly efficient framework for enhanced electron beam control in the context of laser phase plates22, beam modulators and continuous-wave attosecond pulse trains23, resonantly enhanced spectroscopy24–26 and dielectric laser acceleration19,20,27. Our work introduces a universal platform for exploring free-electron quantum optics28–31, with potential future developments in strong coupling, local quantum probing and electron–photon entanglement.

Suppression of instabilities in the transport of a high-power electron beam in the forevacuum pressure range using low-energy thermionic electrons

We report the results of our study on the effect of injection of low-energy thermionic electrons on the suppression of instabilities of the beam-plasma discharge (BPD) type in a beam plasma during the transport of a powerful continuous electron beam generated by a plasma–cathode electron source in the forevacuum range of pressure. As result of thermionic electron injection, the plasma electron temperature decreased to 0.3 eV and the plasma density decreased by an order of magnitude to 1015 m−3. The minimal thermoelectron current required for suppressing the BPD increases with increasing emission current and decreases with increase of the beam accelerating voltage.