Simulation of Secondary Electron and Backscattered Electron Emission in A6 Relativistic Magnetron Driven by Different Cathode

Prticle-in-cell（PIC） simulations demonstrated that,when the relativistic magnetron with diffraction output（MDO） is applied with a 410 kV voltage pulse,or when the relativistic magnetron with radial output is applied with a 350 kV voltage pulse,electrons emitted from the cathode with high energy will strike the anode block wall.The emitted secondary electrons and backscattered electrons affect the interaction between electrons and RF fields induced by the operating modes,which decreases the output power in the radial output relativistic magnetron by about 15%（10%for the axial output relativistic magnetron）,decreases the anode current by about 5%（5%for the axial output relativistic magnetron）,and leads to a decrease of electronic efficiency by 8%（6%for the axial output relativistic magnetron）.The peak value of the current formed by secondary and backscattered current equals nearly half of the amplitude of the anode current,which may help the growth of parasitic modes when the applied magnetic field is near the critical magnetic field separating neighboring modes.Thus,mode competition becomes more serious.

D-A structured high efficiency solid luminogens with tunable emissions： Molecular design and photophysical properties

Fabrication of efficient solid luminogens with tunable emission is both fundamentally significant and technically important. Herein, based on our previous strategy for the construction of efficient and multifunctional solid luminogens through the combination of diverse aggregation-induced emission （ALE） units with other functional moieties, a group of luminophores with electron donor-acceptor （D-A） structure and typical intramolecular charge transfer （ICT） characteristics, namely CZ-DCDPP, DPA-DCDPP and DBPA-DCDPP were synthesized and investigated. The presence of twisting and AlE-active 2,3- dicyano-S,6-diphenylpyrazine （DCDPP） moiety endows them highly emissive in the solid states, whereas the introduction of arylamines with varied electron-donating capacity and different conjugation render them with tunable solid emissions from green to red. While CZ-DCDPP and DPA-DCDPP solids exhibit distinct mechanochromism, both DPA-DCDPP and DBPA-DCDPP solids can generate efficient red emission. Owing to their high efficiency, remarkable thermal and morphological stabilities and moreover red emission, they are promising for diverse optoelectronic and biological applications.

Incorporation of N-doped biochar into zero-valent iron for efficient reductive degradation of neonicotinoids:mechanism and performance

The extensive use of neonicotinoids on food crops for pest management has resulted in substantial environmental contamination.It is imperative to develop an effective remediation material and technique as well as to determine the evolution pathways of products.Here,novel ball-milled nitrogen-doped biochar(NBC)-modified zero-valent iron(ZVI)composites(named MNBC-ZVI)were fabricated and applied to degrading neonicotinoids.Based on the characterization results,NBC incorporation introduced N-doped sites and new allying heterojunctions and achieved surface charge redistribution,rapid electron transfer,and higher hydrophobicity of ZVI particles.As a result,the interaction between ZVI particles and thiamethoxam(a typical neonicotinoid)was improved,and the adsorption-desorption and reductive degradation of thiamethoxam and·H generation steps were optimized.MNBC-ZVI could rapidly degrade 100%of 10 mg·L^(−1) thiamethoxam within 360 min,its reduction rate constant was 12.1-fold greater than that of pristine ZVI,and the electron efficiency increased from 29.7%to 57.8%.This improved reactivity and selectivity resulted from increased electron transfer,enhanced hydrophobicity,and reduced accumulation of iron mud.Moreover,the degradation of neonicotinoids occurred mainly via nitrate reduction and dichlorination,and toxicity tests with degradation intermediates revealed that neonicotinoids undergo rapid detoxification.Remarkably,MNBCZVI also presented favorable tolerance to various anions,humic acid,wastewater and contaminated soil,as well as high reusability.This work offers an efficient and economic biochar-ZVI remediation technology for the rapid degradation and detoxification of neonicotinoids,significantly contributes to knowledge on the relevant removal mechanism and further advances the synthesis of highly reactive and environmentally friendly materials.

Electron transfer dynamics in Schottky junction photocatalyst during electron donor-assisted hydrogen production

Electron donors(EDs)are widely used to improve the H 2 production performance of Schottky junction photocatalysts,but the functions of EDs are still unknown from the perspective of electron transfer dy-namics.Herein,Pt nanocluster-decorated CdS nanorod is successfully prepared to construct a typical CdS/Pt Schottky junction.Pt nanoclusters with a diameter of∼2 nm are deposited on the surface of CdS nanorods by in situ photoreduction at sub-zero temperature.The CdS/Pt photocatalyst using lactic acid shows a higher H_(2)production rate of 4762μmol g^(-1)h^(-1)compared to that using methanol,tri-ethanolamine,and glycerol.To understand the cause,the dynamics of photogenerated carriers in CdS/Pt photocatalysts during ED-assisted H_(2)production are revealed by femtosecond transient absorption spec-troscopy.Among the four organic EDs,lactic acid enables the fastest electron transfer rate of 1.8×10^(9)s^(-1)and the highest electron transfer efficiency of 76%at the CdS/Pt interface due to the most efficient hole consumption.This work sheds light on the importance of efficient interfacial electron transfer for im-proving the photocatalytic performance of Schottky junction photocatalysts.

Electron transmission ef f iciency of gating-GEM foil for TPC

In a TPC, ion feedback from the readout detector can cause a space-charge effect and distort the electrical field in the drift region. Gating is one of the effective methods to solve this problem, which can block ions at the expense of losing a certain amount of primary electrons. Compared with the traditional design with a wire structure, gating based on GEM foil is more attractive because of its simplicity. In this paper, the factors influencing the electron transmission efficiency are studied with simulations and experiments. After optimizing all these parameters, an electron transmission efficiency over 80% is obtained.

Synergistic effect of TiO_2 hierarchical submicrospheres for high performance dye-sensitized solar cells

The performance of dye-sensitized solar cells(DSCs) could be improved by using rationally designed mesoporous film structure for electron collection, dye adsorption and light scattering. The development of a novel double layer film prepared by TiO_2 hierarchical submicrospheres and nanoparticles was reported in this article. The submicrospheres were composed of rutile nanorods of 10 nm diameter and the length of 150–250 nm, which facilitated fast electron transport, charge collection and light scattering. Using a double layer structure consisting of the 10 wt% film as a dye loading layer and the 50 wt% film as the light scattering layer, C101 sensitizer and liquid electrolyte, DSC yielded power conversion efficiency of 9.68% under 1 sun illumination.

Spatial resolution optimization in a THGEM-based UV photon detector

Introduction THick Gas Electron Multiplier(THGEM)is considered in many UV photon detector applications.It has the capability of detecting single photon and imaging with high sensitivity.Operating parameters such as choice of gas mixture,pressure,drift field,drift gap,multiplication voltage,induction field and induction gap play an important role in deciding the spatial resolution of the detector.Detailed simulation study enables to optimize the above-mentioned parameters for a given THGEM-based imaging detector and hence to achieve improved performance for the same.Materials and methods Simulation,using ANSYS and Garfield++,starts with the release of primary electrons at random coordinates on the photocathode plane.They are tracked as they pass through the drift gap and THGEM hole till the electron cloud reaches anode plane.Distribution of electron cloud on the anode plane along X and Y axis is plotted in histogram and fitted with Gaussian function to determine spatial resolution.Ar/CO_(2)(70:30)mixture,which shows higher ETE and lower transverse diffusion,is chosen for this simulation study.Conclusion Transverse diffusion has a major impact on both ETE and the spatial resolution.Lower transverse diffusion coefficient is always desired for having better resolution as well as for ETE.It is found from the simulation study that higher gas pressure,lower drift field and induction field,smaller drift and induction gap can provide optimum detection efficiency with the best spatial resolution.The simulation method proposed here can also be extended to X-ray imaging detectors.

Organic functional materials based buffer layers for efficient perovskite solar cells

In this review, we highlight the recent development of organic π-functional materials as buffer layers in constructing efficient perovskite solar cells（PVSCs）. By following a brief introduction on the PVSC development, device architecture and material design features, we exemplified the exciting progresses made in field by exploiting organic π-functional materials based hole and electron transport layers（HTLs and ETLs） to enable high-performance PVSCs.

Highly efficient blue organic light-emitting diodes using various hole and electron confinement layers

In this Letter, blue phosphorescence organic light-emitting diodes （PHOLEDs） employ structures for electron and/or hole confinement; 1,3,5-tris（N-phenylbenzimiazole-2-yl）benzene is used as a hole confinement layer and tris-（phenylpyrazole）iridium [Ir（ppz）3] is utilized for an electron confinement layer （ECL）. The electrical and optical properties of the fabricated blue PHOLEDs with various carrier-confinement structures are analyzed. Structures with a large ehergy offset between the carrier confinement and emitting layers enhance the charge-carrier balance in the emitting region, resulting from the effective carrier confinement. The maximum external quantum efficiency of the blue PHOLEDs with the double-ECLs is 24.02% at 1500 cd/m^2 and its luminous efficiency is 43.76 cd/A, which is 70.47% improved compared to the device without a carrier-confinement layer.