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Transition-edge sensors (TESs) have the potential to perform electron spectroscopic measurements with far greater measurement rates and efficiencies than can be achieved using existing electron spectrometers. Existing spectrometers filter electrons by energy before detecting a narrow energy band at a time, discarding the vast majority of electrons available for measurement. In contrast, TESs have intrinsic energy sensitivity and so do not require prior filtering to perform energy-resolved measurements. Despite this fundamental advantage, TES electron spectroscopy has not, to our knowledge, previously been reported in the literature. We present the results of a set of proof-of-principle experiments demonstrating TES electron spectroscopy experiments using Mo/Au TESs repurposed for electron calorimetry. Using these detectors, we successfully measured the electron spectrum generated by an electron beam striking a graphite target with energies between 750 and 2000 eV, at a noise-limited energy resolution of 4 eV. Based on the findings of these experiments, we suggest improvements that could be made to TES design to enhance their electron detection capabilities through the use of a dedicated electron absorber in the device with integrated electron optics. [ABSTRACT FROM AUTHOR]

A model is presented for simulating the electron beam within the entire gyrotron geometry using an electron optics code. The model incorporates the influence of the electromagnetic fields generated by the cavity's operational mode through a simple self-consistent approach. This simulation method proves highly beneficial for investigating the effects occurring within the complete gyrotron structure. One such application includes the examination of ions and electrons, resulting from the ionization of residual gas molecules upon collision with the electron beam. By calculating the trajectories of these particles, interesting conclusions can be drawn. [ABSTRACT FROM AUTHOR]

Theoretical models are presented for quasi-optical four-port acoustic devices based on NEMS-coupled beam arrays. Analogies with coupled mode devices in microwaves, ultrasonics, optics, and electron wave optics are first reviewed, together with coupled beam filters. Power transfer between two mechanically coupled, electrostatically driven, coupled beam arrays is then demonstrated using a lumped element model, and the conditions for full power transfer are established. Four-port devices, including directional couplers and coupler filters with complementary transmission ports, are then demonstrated. Predictions are verified for realistic device layouts using the stiffness matrix method. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) photodetectors (PDs) based on nanowire (NW) hold significant promise for applications in fire detection, optical communication, and environmental monitoring. As optoelectronic devices evolve towards lower dimensionality, multifunctionality, and integrability, multicolor PDs have become a research hotspot in optics and electronic information. This study investigates the enhancement of detection capability in a light-trapping ZnO NW array through modification with Pt nanoparticles (NPs) via magnetron sputtering and hydrothermal synthesis. The optimized PD exhibits superior performance, achieving a responsivity of 12.49 A/W, detectivity of 4.07 × 1012 Jones, and external quantum efficiency (EQE) of 4.19 × 103%, respectively. In addition, the Pt NPs/ZnO NW/ZnO PD maintains spectral selectivity in the UV region. These findings show the pivotal role of Pt NPs in enhancing photodetection performance through their strong light absorption and scattering properties. This improvement is associated with localized surface plasmon resonance induced by the Pt NPs, leading to enhanced incident light and interfacial charge separation for the specialized configurations of the nanodevice. Utilizing metal NPs for device modification represents a breakthrough that positively affects the preparation of high-performance ZnO-based UV PDs. [ABSTRACT FROM AUTHOR]

Spin beam splitter is one of the building blocks of graphene spintronics. Here, we adopt the concept of electron optics and design a new type of spin beam splitter by analogy with Brewster's law. The device is a pristine/ferromagnetic/pristine (P/M/P) graphene junction, where the M region is formed by a proximity effect of ferromagnetic insulators, such as EuO, and acts as an "optically thinner medium" relative to the P region. It is found that, when standing waves are formed in the M region with a length of integral multiple of the half longitudinal wavelength of electrons, electrons with the corresponding spin can pass completely through the junction and only electrons with the other spin are reflected by the P/M interface. This manifests Brewster's law and a spin beam splitter. It is also demonstrated that, due to the strong electric field effect of graphene, the Brewster angles for both spins can be monotonically modulated by a gate voltage in the M region in the whole range of − π / 2 to π / 2. Thus, our proposed spin beam splitter is not only an easily implemented and widely tunable build block for spintronics but also an interesting demonstration of electron optics. [ABSTRACT FROM AUTHOR]

Edge states of a topological insulator can be used to explore fundamental science emerging at the interface of low dimensionality and topology. Achieving a robust conductance quantization, however, has proven challenging for helical edge states. In this work, we show wide resistance plateaus in kink states—a manifestation of the quantum valley Hall effect in Bernal bilayer graphene—quantized to the predicted value at zero magnetic field. The plateau resistance has a very weak temperature dependence up to 50 kelvin and is flat within a dc bias window of tens of millivolts. We demonstrate the electrical operation of a topology-controlled switch with an on/off ratio of 200. These results demonstrate the robustness and tunability of the kink states and its promise in constructing electron quantum optics devices. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Intelligent Agriculture Mechanization is the property of Nanjing Institute of Agricultural Mechanization and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Electron beam (e‐beam) with a small spot size is the key to produce microfocus x‐ray source. The spot size of the e‐beam can be controlled by changing the aperture angle at the target, and the focus size of the microfocus x‐ray source is changed accordingly. At the same time, the SNR (Signal‐to‐Noise Ratio) of the image is reduced because the aperture produces secondary x‐ray, which interferes with the x‐ray imaging. In this paper, the aperture size and its position are optimized for getting the smallest spot size of the e‐beam, and the experimental results show that the resolution is 0.8 μm with the aperture size of 0.5 mm. In addition, this paper also presents that the image's SNR can be improved by coating carbon film on the back surface of the aperture. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We explore the possibility of attaining valley-dependent tunnelling and confinement using proximity-induced spin-orbit couplings (SOCs) in graphene-based heterostructures. We consider gate-tunable asymmetric quantum dots (AQDs) on graphene heterostructures and exhibiting a C 3 v and/or C 6 v symmetry. By employing a tight-binding model, we explicitly reveal a pure valley confinement and valley signal in AQDs by streaming the valley local density, leading to valley-charge separation in real space. The confinement of the valley quasi-bound states is sensitive to the locally induced SOCs and to the spatial distribution of the induced AQDs; it is also robust against on-site disorder. The adopted process of attaining a pure valley-Hall conductivity and confinement with zero charge currents is expected to provide more options towards valley-dependent electron optics. [ABSTRACT FROM AUTHOR]

Electron optics introducing the optical concepts into the electronic system unifies the propagation and interference behaviors of different waves and promises nontrivial electronic applications. Due to the high mobility of massless Dirac fermions (MDFs), Dirac materials are suitable for the exploration of optics-like phenomena, in which the Goos–Hänchen shift is an outstanding example. The Goos–Hänchen shift has been studied very well for isotropic MDFs, e.g., in graphene, the relevant generalization to anisotropic MDFs is interesting but lacking. Here, we study the Goos–Hänchen shift of the reflected MDFs by n p junctions based on 8-Pmmn borophene, in which MDFs are tilted. The Goos–Hänchen shift of tilted MDFs has a strong dependence on the junction direction, providing an additional tunability. Accounting for two valleys coupled by the time-reversal symmetry, the valley-contrasting Goos–Hänchen shift is demonstrated, this feature favors the use of 8-Pmmn borophene n p junctions in valleytronics. This study is helpful to understand the anomalous shift of tilted MDFs along the longitudinal interface of np junctions, and implies the potential applications in valleytronics of 8-Pmmn borophene junctions. [ABSTRACT FROM AUTHOR]

There has been a recent uptake in the use of polyether-ether-ketone (PEEK), which is an organic thermoplastic polymer, in the manufacturing of various medical devices, implants, and equipment. Finding the best time and procedure for PEEK after sulfonation is the goal of this research. A total of 30 PEEK discs were sulfonated in this study by immersing them in concentrated (H2SO4) sulfuric acid for various durations and subsequently treated using various post-treatment techniques. Five experiments were carried out, aimed studying the effect of immersion time (5 s–2 min). The methods used as post-treatment were hydrothermal treatment, immersion in NaOH, and washing with acetone. The sulfonation time was measured, and the post-treatment techniques, surface characterizations, were conducted using scanning electron microscopy (SEM) (Electron Optics Instruments, LLC., West Orange, NJ, USA), atomic force microscopy (AFM) (AFM, Vía Burton, CA, USA), and hydrophilic properties. The results were confirmed by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The findings of this study demonstrate that sulfonating PEEK caused a structure with a porous network to form in every sample. As the sulfonation time increased, the porous structure became more noticeable and the concentration increased. As a consequence, the roughness of the surface increased notably, and the modified PEEK surface's wettability improved noticeably. Hydrothermal treatment was determined to be the most successful way for eliminating the leftover sulfuric acid, and sulfonation for 2 min was determined to be ideal. By understanding the best post-treatment procedures and ideal sulfonation duration, a theoretical foundation for the production of sulfonated PEEK for orthopedic uses may be laid. [ABSTRACT FROM AUTHOR]

A numerical model is presented to describe the electron beam neutralization during long-pulse and continuous-wave operation in gyrotrons. This model has been implemented in the electrostatic, self-consistent electron optics code Ariadne. Using this model, the electron beam parameters in the cavity could be determined as a function of the level of neutralization. The electron beam was shown to be partially neutralized in the cavity, and the effect of neutralization on the beam properties was investigated for a cylindrical gyrotron. This study was extended to a coaxial cavity gyrotron, identifying two ion trapping regimes, which only had a minor impact on the beam parameters. [ABSTRACT FROM AUTHOR]

Recent developments on the electron optics simulator (EOS) are reported in this paper. The EOS is a finite element two-dimensional (2D) and three-dimensional (3D) electrostatic particle steady-state trajectory code that has been widely used for beam optics modeling of vacuum electronic devices. To extend the application scope and improve the computation efficiency, four significant advances have been made and are presented in this paper. First, the code is reprogrammed to consider physical models that contain dielectrics and to support charge excitation. Second, more primary particle emission models are added in EOS to meet the needs for simulating electron and ion optics devices for diverse applications. For the precise simulation of the secondary electron emission, the Vaughan model is improved, and the Furman model is newly added in EOS. Finally, the algebraic multigrid algorithm has been embedded in EOS, which can significantly improve the computation efficiency for problems with large-scale matrices. For these developments, the necessary principles and corresponding performance are shown in detail in this paper. [ABSTRACT FROM AUTHOR]

In electron optics, calculation of the electric field plays a major role in all computations and simulations. Accurate field calculation methods such as the finite element method (FEM), boundary element method and finite difference method, have been used for years. However, such methods are computationally very expensive and make the computer simulation challenging or even infeasible when trying to apply automated design of electrostatic lens systems with many free parameters. Hence, for years, electron optics scientists have been searching for a fast and accurate method of field calculation to tackle the aforementioned problem in the design and optimization of electrostatic electron lens systems. This paper presents a novel method for fast electric field calculation in electrostatic electron lens systems with reasonably high accuracy to enable the electron-optical designers to design and optimize an electrostatic lens system with many free parameters in a reasonably short time. The essence of the method is to express the off-axis potential in an axially symmetrical coordinate system in terms of derivatives of the axial potential up to the fourth order, and equate this to the potential of the electrode at that axial position. Doing this for a limited number of axial positions, we get a set of equations that can be solved to obtain the axial potential, necessary for calculating the lens properties. We name this method the fourth-order electrode method because we take the axial derivatives up to the fourth order. To solve the equations, a quintic spline approximation of the axial potential is calculated by solving three sets of linear equations simultaneously. The sets of equations are extracted from the Laplace equation and the fundamental equations that describe a quintic spline. The accuracy and speed of this method is compared with other field calculation methods, such as the FEM and second order electrode method (SOEM). The new field calculation method is implemented in design/optimization of electrostatic lens systems by using a genetic algorithm based optimization program for electrostatic lens systems developed by the authors. The effectiveness of this new field calculation method in optimizing optical parameters of electrostatic lens systems is compared with FEM and SOEM and the results are presented. It should be noted that the formulation is derived for general axis symmetrical electrostatic electron lens systems, however the examples shown in this paper are with cylindrical electrodes due to the simplicity of the implementation in the software. [ABSTRACT FROM AUTHOR]

The paper is devoted to a comparison of the results of an experimental study of a 28 GHz/25 kW gyrotron with a magnetically shielded system and the results of calculating the electron–wave interaction with the use of the ANGEL software code on the basis of a self-consistent model with an unfixed radio-frequency field structure. The good agreement between the results confirms the validity of using the developed code for creation of new gyrotrons. Comparison of various experimental data with the calculation results for the electron–wave interaction as well as for electron optics makes possible implicit reevaluation of the actual values of some important gyrotron parameters (the electron pitch factor, transverse velocity spread, etc.). [ABSTRACT FROM AUTHOR]

We investigate the coherence properties of a transmission electron microscope by analyzing nano-diffraction speckles originating from bulk metallic glass. The spatial correlation function of the coherent diffraction patterns, obtained in the transmission geometry, reveals the highly coherent nature of the electron probe beam and its spatial dimension incident on the sample. Quantitative agreement between the measured speckle contrast and an analytical model yields estimates for the transverse and longitudinal coherence lengths of the source. We also demonstrate that the coherence can be controlled by changing the beam convergence angle. Our findings underscore the preservation of electron beam coherence throughout the electron optics, as evidenced by the high-contrast speckles observed in the scattering patterns of the amorphous system. This study paves the way for the application of advanced coherent diffraction methodologies to investigate local structures and dynamics occurring at atomic-length scales across a diverse range of materials. [ABSTRACT FROM AUTHOR]

In this paper, we study reversibility of Riemann Curvature and Ricci curvature for the Ingarden-Támassy metric and prove two global results. First, we prove that a Ingarden-Támassy metric is R-reversible if and only if si = 0; sij|k = 0. Then we show that a Ingarden-Támassy metric is Riccireversible if and only if si = 0. [ABSTRACT FROM AUTHOR]

Over the past few years, electron ptychography has drawn considerable attention for its ability to recover high contrast and ultra-high resolution images without the need for high quality electron optics. In this Letter, we focus on electron ptychography's other potential benefits: quantitatively mapping phase variations resulting from magnetic and electric fields over extended fields of view. To this end, we propose an implementation of near-field ptychography that employs an amplitude mask located in the electron microscope's condenser aperture plane. We demonstrate the capabilities of our method by imaging a magnetic Permalloy sample and compare our results with those of off-axis electron holography. [ABSTRACT FROM AUTHOR]

Spectroscopic photoemission microscopy is a well-established method to investigate the electronic structure of surfaces. In modern photoemission microscopes, the electron optics allow imaging of the image plane, momentum plane, or dispersive plane, depending on the lens setting. Furthermore, apertures allow filtering of energy-, real-, and momentum space. Here, we describe how a standard spectroscopic and low-energy electron microscope can be equipped with an additional slit at the entrance of the already present hemispherical analyzer to enable an angle- and energy-resolved photoemission mode with micrometer spatial selectivity. We apply a photogrammetric calibration to correct for image distortions of the projective system behind the analyzer and present spectra recorded on Au(111) as a benchmark. Our approach makes data acquisition in energy–momentum space more efficient, which is a necessity for laser-based pump–probe photoemission microscopy with femtosecond time resolution. [ABSTRACT FROM AUTHOR]

In this paper, we studied the operability of various components of vacuum electronic devices manufactured using the novel chemical metallization of photopolymer 3D-printed structures technology (CMPS), which is being applied at the Institute of Applied Physics, Russian Academy of Sciences (IAP RAS), for operation from microwave to sub-terahertz ranges. The key feature of this production method is the 3D printing (SLA/DLP, MJM technologies) of products and their further metallization. The paper presents the main stages of the process of chemical copper plating of polymer bases in various electrodynamic systems with complex shapes. A significant difference in the geometry and operating conditions of the created elements forms certain approaches to their production, as described in this work. Experimental studies of the implemented microwave components were carried out up to 700 GHz in the "cold" measurements; some electrodynamic structures were examined under conditions of sub-gigawatt peak power; and complex-shaped electrodes with cooling channels were tested under a continuous high thermal load. The conducted research has demonstrated the high potential of the developed methods of additive manufacturing of microwave device components and the prospects for their successful application in the described areas. [ABSTRACT FROM AUTHOR]

An electron is a quantum particle and behaves as both a particle and a probability wave. On account of this it can be controlled in a similar way to a photon and electronic devices can be designed in analogy to those based on light when there is minimal excitation of the underlying Fermi sea. Here, splitting of the electron wavefunction is explored for systems supporting Dirac type physics, with a focus on graphene but being equally applicable to electronic states in topological insulators, liquid helium, and other systems described relativistically. Electron beam‐splitters and superfocusers are analysed along with propagation through nanoribbons, demonstrating that the waveform, system geometry, and energies all need to balance to maximise the probability density and hence lifetime of the flying electron. These findings form the basis for novel quantum electron optics. [ABSTRACT FROM AUTHOR]

Coherence is one of the limiting factors in off-axis electron holography applications. This paper reports methods to improve coherence ∼18-fold by using a smaller biprism and implementing a direct electron counting camera (K-camera) in combination with an imaging filter system. We achieved 0.4 nm fringe spacing with a 1.5 μm field-of-view and ∼33% fringe contrast. The maximum coherence number, N′ , of ∼1.8 × 103 was achieved, where N′ is defined as the number of fringes times fringe contrast. High spatial resolution junction profile images (nm scale) of n-channel and p-channel field-effect transistors (nFET and pFET) are demonstrated with a large field-of-view (μm scale). [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We propose a source of purely electronic energy-entangled states implemented in a solid-state system with potential applications in quantum information protocols based on electrons. The proposed device relies on the standard tools of electron quantum optics and exploits entanglement of the Cooper pairs of a BCS superconductor. The latter is coupled via an adjustable quantum point contact to two opposite spin-polarized electron wave-guides, which are driven by trains of Lorentzian pulses. This specific choice for the drive is crucial to inject purely electronic entangled states devoid of spurious electron–hole pairs. In the Andreev regime, a perturbative calculation in the tunnel coupling confirms that entangled electrons states are generated at the output of the normal side. For arbitrary tunnel coupling and for a periodic drive, direct current and noise (auto and cross correlations) are computed numerically using a Keldysh–Nambu–Floquet formalism. Importantly, for a periodic drive, the production of these states can be controlled in time, thus implementing an on-demand source of entangled states. We exploit realistic experimental parameters for our device to identify its optimal functioning point. [ABSTRACT FROM AUTHOR]

Recently, Schreiber et al (2024 New J. Phys. 26 043012) have presented the theory of an electron lens acting through the Aharonov–Bohm effect in the field-free opening of a static toroidal magnetic field. In this Comment, three key results of this theory are shown to be incorrect due to six basic calculation errors. The errors are corrected, and three correspondingly modified key results are derived. These results are discussed with respect to the hypothetical lens effect and the underlying Aharonov–Bohm effect.

The resemblance between electrons and optical waves has strongly driven the advancement of mesoscopic physics, evidenced by the widespread use of terms such as fermion or electron optics. However, electron waves have yet to be understood in open cavity structures which have provided contemporary optics with rich insight towards non-Hermitian systems and complex interactions between resonance modes. Here, we report the realization of an open cavity resonator in a two-dimensional electronic system. We studied the resonant electron modes within the cavity and resolved the signatures of longitudinal and transverse quantization, showing that the modes are robust despite the cavity being highly coupled to the open background continuum. The transverse modes were investigated by applying a controlled deformation to the cavity, and their spatial distributions were further analyzed using magnetoconductance measurements and numerical simulation. These results lay the groundwork to exploring matter waves in the context of modern optical frameworks. Electron optics draws upon the resemblance between electron and optical waves. Here, the authors report on the observation of electron mode formation in open cavity resonators realized in a GaAs/AlGaAs two-dimensional electronic gas. [ABSTRACT FROM AUTHOR]

In this paper, the design and multimode analysis of a single cavity Ka-band gyro-twystron have been presented. The present amplifier has been studied for its beam-wave interaction by using a nonlinear multimode analysis, which has also been verified with a 3D Particle-In-Cell (PIC) simulation. A single anode magnetron injection gun (MIG) has been designed with a ∼4% velocity spread using electron optics code. The PIC simulation of the current amplifier predicted an RF output power of ∼240 kW in TE01 mode at 35 GHz. The power gain, electronic efficiency, and 3-dB bandwidth were calculated as ∼53 dB, ∼37%, and ∼2 GHz, respectively, using the electron beam of 65 kV, 10 A with the velocity ratio of 1.4. Also, a collector is designed with a heat wall loading 0.116 kW/cm2 for the proposed design. [ABSTRACT FROM AUTHOR]

In this paper, we studied the operability of various components of vacuum electronic devices manufactured using the novel chemical metallization of photopolymer 3D-printed structures technology (CMPS), which is being applied at the Institute of Applied Physics, Russian Academy of Sciences (IAP RAS), for operation from microwave to sub-terahertz ranges. The key feature of this production method is the 3D printing (SLA/DLP, MJM technologies) of products and their further metallization. The paper presents the main stages of the process of chemical copper plating of polymer bases in various electrodynamic systems with complex shapes. A significant difference in the geometry and operating conditions of the created elements forms certain approaches to their production, as described in this work. Experimental studies of the implemented microwave components were carried out up to 700 GHz in the “cold” measurements; some electrodynamic structures were examined under conditions of sub-gigawatt peak power; and complex-shaped electrodes with cooling channels were tested under a continuous high thermal load. The conducted research has demonstrated the high potential of the developed methods of additive manufacturing of microwave device components and the prospects for their successful application in the described areas.

The average transverse energy of field emission electrons at the cathode surface is one of the key factors that determines the virtual source size, hence the transverse spatial coherence of field emitters. In the past, the subject has been intensively studied by classical electron optics analysis but its wave optical studies are rare. In this work, we therefore aim to elucidate the influence of the transverse momentum in solid on the transverse structure of the wave function of field emission electrons. From the calculation extending the standard field emission theory within the WKB approximation for model planar free-electron metal, we obtained a Gaussian-beam-type wave function that exhibits a minimum transverse width at the cathode surface as determined by the average transverse energy and propagates the first few nanometers with a limited transverse spread. At far field, the wave function spreads as the electron propagates away from the cathode surface. Comparison with classical results indicated that, in the present planar field emitter model, the neglect of the three-dimensional potential around the tip apexes of actual field emitters underestimates the transverse spread up to a factor of 2. However, when the cathode size is finite and the electrons in the solid are phase-coherent within the source area, the transverse spread is much smaller than that of the point-source wave function. Our result indicates that the intrinsic transverse emittance of a finite size fully coherent field emitter is much smaller than the value predicted by classical analysis. [ABSTRACT FROM AUTHOR]

Three D‐A type blue‐light TADF materials with AIE characteristic have been calculated at atomic level in this paper. The design materials base on carbazole as donor groups and benzenyl‐trifluoride/ cyanobenzene as accept groups. Geometry optimization shows that low binding energy of studied molecules is favorable for synthesis and the optimized molecular structures are highly distorted. Electronic structure analysis proved strong interactions of both inter‐C‐N and C‐C bonds between molecular fragments, and the electronic reconstruction trend and bonding strength are basically consistent for the same type of atom pairs. Frontier molecular orbitals and population analysis demonstrated that HOMO and LUMO are successfully isolated to the receptor and donor. DSCN‐CAZ has the lowest energy due to lower LUMO level. Simulated UV‐Vis spectrum explores that the absorption peak of TADF molecules stand at 253nm‐335 nm and their corresponding excited states all occur pi‐pi* excitation. ESP Surface analysis finds that cyanobenzene fragments were an important factor affecting the stability of the designed TADF molecules. The geometry, electronic structure and optics properties of design materials have been revealed, providing a theoretical basis for developing blue‐light TADF materials with AIE properties. [ABSTRACT FROM AUTHOR]

A Monte Carlo technique has been developed to simulate the expected signal and the statistical noise of x-ray spectrometers that use streak cameras to achieve the time resolution required for ultrafast diagnostics of laser-generated plasmas. The technique accounts for statistics from both the photons incident on the streak camera's photocathode and the electrons emitted by the photocathode travelling through the camera's electron optics to the sensor. We use the technique to optimize the design of a spectrometer, which deduces the temporal history of electron temperature of the hotspot in an inertial confinement fusion implosion from its hard x-ray continuum emission spectra. The technique is general enough to be applied to any instrument using an x-ray streak camera. [ABSTRACT FROM AUTHOR]

Copyright of Eurasian Physical Technical Journal is the property of E.A. Buketov Karaganda University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Graphene nanoribbons (GNRs) are promising components in future nanoelectronics due to the large mobility of graphene electrons and their tunable electronic band gap in combination with recent experimental developments of on-surface chemistry strategies for their growth. Here, we explore a prototype 4-terminal semiconducting device formed by two crossed armchair GNRs (AGNRs) using state-of-the-art first-principles transport methods. We analyze in detail the roles of intersection angle, stacking order, inter-GNR separation, GNR width, and finite voltages on the transport characteristics. Interestingly, when the AGNRs intersect at θ = 60°, electrons injected from one terminal can be split into two outgoing waves with a tunable ratio around 50% and with almost negligible back-reflection. The split electron wave is found to propagate partly straight across the intersection region in one ribbon and partly in one direction of the other ribbon, i.e., in analogy with an optical beam splitter. Our simulations further identify realistic conditions for which this semiconducting device can act as a mechanically controllable electronic beam splitter with possible applications in carbon-based quantum electronic circuits and electron optics. We rationalize our findings with a simple model suggesting that electronic beam splitters can generally be realized with crossed GNRs. [ABSTRACT FROM AUTHOR]

In their recent article, Nfor et al. [Optik - International Journal for Light and Electron Optics 285 (2023) 170951, https://doi.org/10.1016/j.ijleo.2023.170951] have studied, through a dissipative nonlinear Schrödinger equation, the modulational instability and soliton trains in optical fiber media with real and imaginary Raman gains. After finding a steady-state solution of this equation, they have applied the linear stability analysis to investigate its modulational instability. It appears that (i) their proposed steady-state solution is not really a continuous wave solution of their model equation, and (ii) their ansatz used for the modulation perturbation function violate all mathematical/physical rules, leading thus to an inappropriate results. Moreover, during their development on exact analytical solutions, authors have not established conditions under which those analytical solutions may exist, as one can easily verify in subsection 3.1. It is the aim of the present comment to correct all shortcomings about the modulational instability study carried out in their study. We start by presenting the correct steady-state solution of the considered dissipative nonlinear Schrödinger equation, and then investigate with details its modulational instability. We end this comment by establishing conditions under which equation (15) admits analytical solutions of form (16) when a 6 = 0 , and the present some other interesting solutions of this equation (16). [ABSTRACT FROM AUTHOR]

Consolidation of ultrafast optics in electron spectroscopies based on free electron energy exchange with matter has matured significantly over the past two decades, offering an attractive toolbox for the exploration of elementary events with unprecedented spatial and temporal resolution. Here, we propose a technique for monitoring electronic and nuclear molecular dynamics that is based on self-heterodyne coherent beating of a broadband pulse rather than incoherent population transport by a narrowband pulse. This exploits the strong exchange of coherence between the free electron and the sample. An optical pulse initiates matter dynamics, which is followed by inelastic scattering of a delayed high-energy broadband single-electron beam. The interacting and noninteracting beams then interfere to produce a heterodyne-detected signal, which reveals snapshots of the sample charge density by scanning a variable delay T. The spectral interference of the electron probe introduces high-contrast phase information, which makes it possible to record the electronic coherence in the sample. Quantum dynamical simulations of the ultrafast nonradiative conical intersection passage in uracil reveal a strong electronic beating signal imprinted onto the zero-loss peak of the electronic probe in a background-free manner. [ABSTRACT FROM AUTHOR]

The efficiency of the RF power sources is one of the major concerns in the large-scale high-energy accelerator projects such as the future circular collider (FCC) and the compact linear collider (CLIC). The new bunching method, the core stabilization method (CSM), can achieve high efficiency in the case of shorter interactive length. The multibeam klystron (MBK) could accommodate high RF power with a low operating voltage, compared with a single-beam klystron. This article presents the design and simulation of a 650-MHz, 0.9-MW continuous wave (CW) CSM MBK. The detailed design of a six-beam optics system is also elaborated in this article. The performance of such a device was validated by the 3-D particle-in-cell (PIC)-code computer simulation. With an operating voltage of 50 kV, PIC simulation predicts an efficiency of 81.8%. [ABSTRACT FROM AUTHOR]

The magnetic lens (magnetic field lens) uses a magnetic field rather than an equipotential plane. This work presents a modelling of the design of a focused magnetic lens. Its main purpose is to reveal the possibility of this lens to eliminate aberrations and to determine the extent of its potential to be included in the design of electron microscopes and electron beam melting systems. This work was accomplished by using COMSOL Multiphysics simulation software. The magnetic lens was tested to determine the possibility of its inclusion in electron microscopes by changing the bore radius from 1 to 4 step by step. The proposed mathematical model was proven as an excellent tool in electron optics. [ABSTRACT FROM AUTHOR]

The investigation of nonlinear transient characteristics of gallium arsenide (GaAs) photoconductive semiconductor switches (PCSS) is of great significance for its applications in pulsed power technology. In this letter, the laser diode (LD) energy of $2~\mu \text{J}$ is employed to trigger the opposed-electrode GaAs PCSS. The compressed pulse width and increased amplitude are obtained as the bias electric field increases from 6kV/cm to 34kV/cm. It is numerically modeled the transient electric field distribution along the photogenerated carriers’ transport. Results reveal that pulse compression effect (PCE) can be attributed to the negative differential mobility (NDM) and electric-field screening (EFS) effect. The compression of pulse width on time scale provides a possibility to relieve the heat accumulation on time scale, and further to suppress the device failure for the potential high-repetition-rate applications. [ABSTRACT FROM AUTHOR]