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We report on the energy dependence of the photoemission time delay from the single-element layered dielectric HOPG (highly oriented pyrolytic graphite). This system offers the unique opportunity to directly observe the Eisenbud-Wigner- Smith (EWS) time delays related to the bulk electronic band structure without being strongly perturbed by ubiquitous effects of transport, screening, and multiple scattering. We find the experimental streaking time shifts to be sensitive to the modulation of the density of states in the high-energy region (E ≈ 100 eV) of the band structure. The present attosecond chronoscopy experiments reveal an energy-dependent increase of the photoemission time delay when the final state energy of the excited electrons lies in the vicinity of the bandgap providing information difficult to access by conventional spectroscopy. Accompanying simulations further corroborate our interpretation. [ABSTRACT FROM AUTHOR]

Physicists have long studied Landau states and energy levels of electrons in a stable magnetic field. However, when the magnetic field dissipates, the question of how Landau states evolve remains unanswered. This study investigates the magnetic dissipative effect from a quantum mechanics perspective. We establish a quantum master equation that describes a dissipative magnetic field. Subsequently, we solve the master equation using an entangled state representation. Consequently, we found that the Landau state evolves into a binomial quantum state (mixed state) when the magnetic field dissipated. This is in sharp contrast to the case where the Landau state becomes a negative binomial state when an additional harmonic oscillator potential is applied. We hope that this finding will be helpful for the evolution of quantized plasma physics. [ABSTRACT FROM AUTHOR]

The anomalous magnetic moment of the electron, first calculated by Schwinger, lowers the ground state energy of the electron in a weak magnetic field. It is a function of the field and changes signs for large fields, ensuring the stability of the ground state. This has been shown in the past 50 years in numerous papers. The corresponding corrections to the mass of the electron have also been investigated in strong fields using semiclassical methods. We critically review these developments and point out that the calculation for low-lying excited states raises questions. Also, we calculate the contribution from the tadpole diagram, the relevance of which was observed only quite recently. [ABSTRACT FROM AUTHOR]

The optically transparent connecting electrode is much desired in fabrication of tandem optoelectronic devices. Yet, optically transparent materials, such as oxides, are electrically insulating. In this work, we show that low work function oxides Yb2O3 combing with high work function 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN) molecule can be used as effective connecting electrodes to make high performance tandem organic light emitting diodes with negligible voltage loss. For instance, in a tandem device with two emission zones, yielding a brightness of 100 cd/m2, the voltage required is 5.3 V, which is approximately twice that of a single emission zone device. To gain insights into the band alignment of this electrode, we conducted the measurements, including ultraviolet photoelectron spectroscopy to analyze the electronic structures of occupied valence and gap states and reflection electron energy loss spectroscopy to study the unoccupied states. To understand the charge transport and injection behavior of this electrode, we conducted variable temperature charge transport measurements. Our findings reveal the presence of localized gap states within the Yb2O3/HAT-CN structure. These gap states effectively form a conduction pathway for facilitating the transport of charge carriers. At higher temperatures (≥200 K), charge transport is primarily limited by the Efros–Shklovskii type of hopping conduction through the localized states in the Yb2O3. Conversely, at lower temperatures (<200 K), the electrical current is limited by the properties of HAT-CN. These discoveries suggest that localized gap states at the oxides/organic heterojunctions can be effectively utilized in the fabrication of tandem semiconductor devices. [ABSTRACT FROM AUTHOR]

We consider the motion of a body‐point near an attracting center. The body‐point is defined as a particle with the following properties. (a) The body‐point occupies zero volume in space like a point mass. (b) The body‐point has both translational and rotational degrees of freedom like a rigid body. (c) The body‐point is characterized by a larger number of moments of inertia than an ordinary rigid body. Due to the additional moments of inertia, the body‐point acquires dynamic properties that are fundamentally different from the dynamic properties of an ordinary rigid body. We show that the trajectory of the body‐point moving near the attracting center is a spatial curve, and not a flat one, as it would be in the case of a point mass or a rigid body. We study in detail a special case of the body‐point motion, in which the magnitude of the momentum vector remains constant. We show that, in this special case, the region of space where the trajectory of the body‐point is located can be interpreted as the orbital of an electron in a hydrogen atom. Assuming that the body‐point models the electron in the ground energy state, we determine the parameters of our model. We emphasize that the problem of the body‐point motion near an attracting center is considered for the first time, and therefore all theoretical results presented in this paper are novel. Also, for the first time, the model of the body‐point in a central potential field is used to describe the behavior of an electron in a hydrogen atom. [ABSTRACT FROM AUTHOR]

The article focuses on the development of nuclear clocks, a new type of timekeeping device that could surpass current atomic clocks in precision. Topics include recent advancements in nuclear clock research, such as achieving simultaneous operation of all necessary components, the potential for these clocks to explore fundamental physics questions, and the use of precise measurements of thorium-229's excitation energy to improve clock accuracy.

The lattice parameters, bulk modulus, shear modulus, Young's modulus and other mechanical constants of Ir-xRh (x=0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 17, 20, 22, 25, 27, 30) alloys were calculated by using the first-principles analysis method based on density functional theory. The calculation model is established by the virtual crystal potential function approximation method. The effect of Rh doping on the mechanical properties of Ir-Rh alloy was also analyzed from the electronic point of view by calculating the enthalpy change value, electron density of state and energy band structure. The results show that the strength and hardness of the material can be improved by doping a small amount of Rh in Ir. The peak point at Ir-5Rh decreases slightly and then continues to rise, reaching the maximum at Ir-10Rh, and the value is basically the same as that of Ir-5Rh. With the increase of Rh content, the absolute value of enthalpy changed gradually increased from 0.186 eV to 0.634 eV, and the thermodynamic stability of Ir-Rh alloy was improved. In addition, the density of states and band structure of Ir-Rh alloy show that the bond energy increases with the increase of Rh content, and the brittleness of Ir-Rh alloy increases gradually. [ABSTRACT FROM AUTHOR]

Due to presence of magnetic field gradient needed for coherent spin control, dephasing of single-electron spin qubits in silicon quantum dots is often dominated by 1 / f charge noise. We investigate theoretically fluctuations of ground state energy of an electron in gated quantum dot in a realistic Si/SiGe structure. We assume that the charge noise is caused by motion of charges trapped at the semiconductor–oxide interface. We consider a realistic range of trapped charge densities, ρ ∼ 10 10 cm−2, and typical lenghtscales of isotropically distributed displacements of these charges, δ r ≤ 1 nm, and identify pairs (ρ , δ r) for which the amplitude and shape of the noise spectrum are in good agreement with spectra reconstructed in recent experiments on similar structures. [ABSTRACT FROM AUTHOR]

The relativistic convergent close-coupling method is applied to calculate integrated cross sections for the electron-impact excitation of Sn 2 + . Cross sections have been calculated for excitations to all states in the 5s5p, 5 p 2 , 5s6s and 5s5d manifolds from the ground state for projectile electron energies ranging from 24 eV to 500 eV. The total discrete inelastic scattering cross section is also presented. [ABSTRACT FROM AUTHOR]

In recent years, various designs for controlled thermonuclear fusion based on the p11B reaction have been reviewed and optimized. In this article, to achieve more energy gain for p11B neutron-free fusion reaction, we used as newer cross-section formula and entered two key phenomena: a) avalanche and b) kinetics of protons. Then, the effects of bremsstrahlung radiation and ion and electron energy exchange rate have been evaluated by introducing relativistic effects and its role on improving fusion energy gain. As a result, the temperature of the electron is kept lower than that of the ion, which improves fuel performance. Finally, it leads to an increase in the number of protons at higher energies compared to the pure Maxwellian distribution and it causes a significant increase in reactivity compared to previous research. Also, the number of alpha particles obtained through calculations coincides with the latest research and leads to an enhancement of approximately 13%. This means that by improving the fusion cross-section of p11B, our calculations show that considering the avalanche effects, the range of achievable energy gain in the temperature range of 300 to 500 keV and the stable characteristic time of 0.64 ps reaches 89 to 111. While in the same temperature range and with the stable characteristic time of 0.74 ps, regard free of the cross-section, the energy gain range is 75 to 98. [ABSTRACT FROM AUTHOR]

We analyze the effect of longitudinal optical phonons on the energy states of electrons in a nanowire in the presence of Rashba interaction and an in-plane magnetic field. Due to the electron–phonon interaction, an energy splitting appears at zero wave vector accompanied by a downward shift of the dispersion relation in the absence of external magnetic fields. The splitting increases linearly with the product of the Rashba parameter and the dimensionless constant characterizing the Fröhlich Hamiltonian. It also induces an enhancement in the g -factor that is inversely proportional to the strength of the magnetic field. Moreover, we calculate the contribution of Rashba intersubband coupling (RIC) to the electron energy. This contribution does not influence the g -factor for the case of parallel magnetic field to the nanowire, but it causes reduction in it by increasing the angle between the nanowire and the field. [ABSTRACT FROM AUTHOR]

We report on high-level coupled-cluster calculations of electronic states of the neutral endohedral fullerene Li@C20. All computed states of neutral Li@C20 are found to be the charge separated states of the Li+@ C 20 − type. Using the state-of-the-art EA-EOM-CCSD method, we found that neutral Li@C20 (D3d) possesses several valence and superatomic charge separated states with considerable electron binding energies, the strongest bound state of Li+@ C 20 − being the 12Eu state (6.73 eV). The valence charge separated states correspond to two sets of states of C 20 − . The states 12Eu, 12A2u, 22Eu, and 22A2u correspond to the respective bound states of C 20 − , and the states 22A2g, 12Eg, 12A1g, and 42Eu correspond to the unbound states of C 20 − . There are eight superatomic states with electron binding energy higher than 1.0 eV, being much stronger bound than the single weakly bound superatomic state of the parent fullerene anion. The analysis of the radial density distribution of the excess electron on the carbon cage indicates the important role of the inner part of the superatomic states in forming the charge separated states. [ABSTRACT FROM AUTHOR]

We report on high-level coupled-cluster calculations of electronic states of the neutral endohedral fullerene Li@C20. All computed states of neutral Li@C20 are found to be the charge separated states of the Li+@ C 20 − type. Using the state-of-the-art EA-EOM-CCSD method, we found that neutral Li@C20 (D3d) possesses several valence and superatomic charge separated states with considerable electron binding energies, the strongest bound state of Li+@ C 20 − being the 12Eu state (6.73 eV). The valence charge separated states correspond to two sets of states of C 20 − . The states 12Eu, 12A2u, 22Eu, and 22A2u correspond to the respective bound states of C 20 − , and the states 22A2g, 12Eg, 12A1g, and 42Eu correspond to the unbound states of C 20 − . There are eight superatomic states with electron binding energy higher than 1.0 eV, being much stronger bound than the single weakly bound superatomic state of the parent fullerene anion. The analysis of the radial density distribution of the excess electron on the carbon cage indicates the important role of the inner part of the superatomic states in forming the charge separated states. [ABSTRACT FROM AUTHOR]

We elaborate a reduced kinetics model to study humid air plasmas at atmospheric pressure generated by X-ray irradiation. The originality of the present approach is to use the experimental results of the transmission measurements, in the case of a microwave signal by the X-ray-induced plasma filled waveguide, to fit the calculated time evolutions of some plasma parameters such as average electron energies and an effective loss coefficient. The reduced kinetics model used to restitute the transmission measurements is based on the solution of a one-dimensional transport of a guided microwave signal coupled to the calculation of the complex electric conductivity of the plasma. The conductivity is calculated using a simplified kinetics scheme based on three species (electrons, positive ions, and negative ions) and coupled to the electron energy balance equation. The input parameters of the model are the collision cross sections of the electrons impact with air molecules (N2, O2, and H2O) and the electron energy distribution functions pre-tabulated for a large set of average electron energies. The latter takes into account the main processes leading to the decrease of average electron energies. This model is more generally usable for the modelling of weakly ionized atmospheric air plasmas during, for instance, the streamer development in corona or dielectric barrier discharges. [ABSTRACT FROM AUTHOR]

Probing plasmonic properties of surface deposited nanoparticles with high spatial resolution requires the use of a low absorption support. In this work, ultra-thin hexagonal boron nitride (h-BN) flakes are employed as substrates for scanning transmission electron microscopy. The thicknesses of only a few atomic layers, the flat surface, and the large bandgap provide a unique set of properties, which makes h-BN ideally suitable for high resolution plasmon spectroscopy by means of electron energy loss spectroscopy (EELS), especially for small nanoparticles. A facile fabrication process allows the production of h-BN substrates with a thickness of only a few atomic layers. The advantages of h-BN, especially for the low-loss energy region of EEL spectra, are shown in a direct comparison with a silicon nitride substrate. Furthermore, results of the investigation of localized surface plasmon resonances (LSPRs) of Ag and Ag–Au core–shell nanoparticles in the sub-20 nm size regime are presented, confirming the advantages of the fabricated substrate for LSPR mapping. The plasmonic nanoparticles were assembled utilizing the helium nanodroplet synthesis approach, which allows for a very soft deposition and the preservation of the integrity of the ultra-thin substrate. Moreover, it provides a completely solvent and surfactant free environment for the assembly of tailored nanoparticles. [ABSTRACT FROM AUTHOR]

Using our magnetically confined electron transmission apparatus, we report the results of total cross sections (TCSs) for electron scattering from dichloromethane (CH2Cl2). The energy range of this study is 1–300 eV. Wherever possible, the present data are compared to earlier measured TCSs of Wan et al. [J. Chem. Phys. 94, 1865 (1991)] and Karwasz et al. [Phys. Rev. A 59, 1341 (1999)] and to the corresponding theoretical independent atom model with screening corrected additivity rule and interference term (IAM-SCAR+I) results of Krupa et al. [Phys. Rev. A 97, 042702 (2018)] and a spherical complex optical potential formulation calculation of Naghma et al. [J. Electron Spectrosc. Relat. Phenom. 193, 48 (2014)]. Within their respective uncertainties, the present TCS and those of Karwasz et al. are found to be in very good agreement over their common energy range. However, agreement with the results of Wan et al. is quite poor. The importance of the experimentally inherent 'missing angle' effect (see later) on the measured TCS is investigated and found to be significant at the lower energies studied. Indeed, when this effect is accounted for, agreement between our measured TCSs and the corrected IAM-SCAR+I+rotations calculation results are, for energies above about 3 eV, in good accord (to better than 8%). Finally, we observe two σ* shape resonances, consistent with the earlier electron transmission spectroscopy results of Burrow et al. [J. Chem. Phys. 77, 2699 (1982)], at about 2.8 eV and 4.4 eV incident electron energy, in our measured TCS. [ABSTRACT FROM AUTHOR]

The valence electron binding energies and the aromaticity of neutral and charged small boron clusters with three and four atoms are investigated using a combination of the fixed-node diffusion quantum Monte Carlo (FN-DMC) method, the density functional theory, and the Hartree-Fock approximation. The obtained electron binding energies such as the adiabatic detachment energy, vertical detachment energy, adiabatic ionization potential, and the vertical ionization potential are in excellent agreement with available experimental measurements. Their decomposition into three physical components such as the electrostatic potential and exchange interaction, the relaxation energy, and the electronic correlation effects has allowed us to determine that the neutral boron clusters are stabilized by the electrostatic and exchange interactions, while the anionic ones are stabilized by the relaxation and correlation effects. The aromaticity is studied based on electronic structure principles descriptor and on the resonance energy. The FN-DMC results from the electronic structure principles of the energy, hardness, and eletrophilicity have supported the aromaticity of B 3 − , B 4 − , and B4 and partially supported the aromaticity of the clusters B3, B 3 + , and B 4 + . The obtained values for the resonance energy of the clusters B 3 − , B3, B 3 + , B4, B 4 + , and B 4 − are 55.1(7), 54.2(8), 33.9(7), 84(1), 67(1), and 58(1) kcal/mol, respectively. Therefore, the order of decreasing stability of the trimer is B 3 − > B 3 > B 3 + , while for the tetramer it is B 4 > B 4 + > B 4 − , which is in agreement with the results from the molecular orbital analysis. [ABSTRACT FROM AUTHOR]

Lanthanides (Ln3+) doped luminescent materials play critical roles in lighting and display techniques. While increasing experimental and theoretical research have been carried out on aluminate-based phosphors for white light-emitting diodes (WLEDs) over the past decades, most investigation was mainly focused on their luminescent properties; therefore, the local structure of the light emission center remains unclear. Especially, doping-induced local composition and structure modification around the luminescent centers have yet to be unveiled. In this study, we use advanced electron microscopy techniques including electron diffraction (ED), high-resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), in combination with energy dispersive X-ray spectroscopy (EDX) and electron energy loss spectroscopy (EELS), to reveal atomically resolved crystalline and chemical structure of Ce3+ doped CaYAlO4. The microscopic results prove substantial microstructural and compositional inhomogeneities in Ce3+ doped CaYAlO4, especially the appearance of Ce dopant clustering and Ce3+/Ce4+ valence variation. Our research provides a new understanding the structure of Ln3+ doped luminescent materials and will facilitate the materials design for next-generation WLEDs luminescent materials. [ABSTRACT FROM AUTHOR]

The layer-dependent properties are still unclarified in two-dimensional (2D) vertical heterostructures. In this study, we layer-by-layer deposited semimetal β-In2Se3 on monolayer MoS2 to form vertical β-In2Se3/MoS2 heterostructures by chemical vapor deposition. The defect-mediated nucleation mechanism induces β-In2Se3 nanosheets to grow on monolayer MoS2, and the layer number of stacked β-In2Se3 can be precisely regulated from 1 layer (L) to 13 L by prolonging the growth time. The β-In2Se3/MoS2 heterostructures reveal tunable type-II band alignment arrangement by altering the layer number of β-In2Se3, which optimizes the internal electron transfer. Meanwhile, the edge atomic structure of β-In2Se3 stacking on monolayer MoS2 shows the reconstruction derived from large lattice mismatch (∼ 29%), and the presence of β-In2Se3 also further increases the electrical conductivity of β-In2Se3/MoS2 heterostructures. Attributed to abundant layer-dependent edge active sites, edge reconstruction, improved hydrophilicity, and high electrical conductivity of β-In2Se3/MoS2 heterostructures, the edge of β-In2Se3/MoS2 heterostructures exhibits excellent electrocatalytic hydrogen evolution performance. Lower onset potential and smaller Tafel slope can be observed at the edge of monolayer MoS2 coupled with 13-L β-In2Se3. Hence, the outstanding conductive layers coupled with edge reconstruction in 2D vertical heterostructures play decisive roles in the optimization of electron energy levels and improvement of layer-dependent catalytic performance. [ABSTRACT FROM AUTHOR]

In various applications, such as the computation of energy excitation states of electrons and molecules, and the analysis of interstellar clouds, the linear response eigenvalue problem, which is a special type of the Hamiltonian eigenvalue problem, is frequently encountered. However, traditional eigensolvers may not be applicable to this problem owing to its inherently large scale. In fact, we are usually more interested in computing some of the smallest positive eigenvalues. To this end, a trace minimum principle optimization model with orthogonality constraint has been proposed. On this basis, we propose an unconstrained surrogate model called trace minimization via penalty, and we establish its equivalence with the original constrained model, provided that the penalty parameter is larger than a certain threshold. By avoiding the orthogonality constraint, we can use a gradient-type method to solve this model. Specifically, we use the gradient descent method with Barzilai–Borwein step size. Moreover, we develop a restarting strategy for the proposed algorithm whereby higher accuracy and faster convergence can be achieved. This is verified by preliminary experimental results. [ABSTRACT FROM AUTHOR]

[Display omitted] • B 2 C 2 N 2 is explored as potential anticancer drug delivery system. • The interaction of 5-Fluorouracil and Carmustine with B 2 C 2 N 2 is investigated via DFT methods. • The anticancer drug-B 2 C 2 N 2 complexes are found thermodynamically and electronically stable. • FMOs energy gap of B 2 C 2 N 2 changed upon interaction with the drugs. • Noncovalent interactions are confirmed through NCI analysis. Inorganic nanosheets, such as B 2 N 2 C 2 , are a focus of research for advanced materials. B 2 N 2 C 2 exhibits exceptional thermal stability, high mechanical strength, and excellent electrical conductivity, making it ideal for applications in electronics, energy storage devices, and sensors. In this study, we investigated the drug-carrying capabilities of B 2 N 2 C 2 nanosheet toward anticancer F-Uracil (FU) and Carmustine (BCNU) using Density Functional Theory (DFT) calculations. Interaction energy values of −19.36 and −22.17 kcal/mol for FU@B 2 N 2 C 2 and BCNU@ B 2 N 2 C 2 complexes indicate their thermodynamic stability. NBO charge analysis shows the charge transfer from the surface to the analytes in the BCNU@B 2 N 2 C 2 complex and from the analyte to the surface in the FU@B 2 N 2 C 2 complex. The HOMO-LUMO energy gap of pure B 2 N 2 C 2 (3.25 eV) is decreased to 3.22 eV after drug adsorption. Noncovalent interaction (NCI) analysis confirmed the existence of noncovalent interactions between drugs and the B 2 N 2 C 2 sheet. Total density of states (TDOS) spectra provided information about the energy states of electrons in pure B 2 N 2 C 2 and drug@B 2 N 2 C 2 complexes. These findings highlight the potential of B 2 N 2 C 2 nanosheet as targeted drug delivery substrate for anticancer drugs in future. [ABSTRACT FROM AUTHOR]

We report the approach to designing the hybrid gas sensor based on the array of vertically-oriented InAs nanowires and gas-permeable film made of single-walled carbon nanotubes (SWCNTs). We probe the sensor performance at room temperature towards isopropyl alcohol analyte, whose highest occupied molecular orbital energy to be in-between the Fermi levels of SWCNTs and InAs, to check the main contributing mechanism. Our theoretical analysis revealed that electronic systems of both materials contribute to sensor response. Our findings indicate that the sensor response to isopropyl alcohol in a mixture with dry and humid air primarily stems from its interaction with carbon nanotubes, although it also involves an interplay between the electron energy states of SWCNTs and InAs. We also test the sensor response to methanol, ethanol, and butanol analytes and demonstrate that it enhances with a molecule weight. The proposed sensor design can be further optimized to capture vector signals under a multivariate approach to selectively determine various analytes. • Gas sensor based on of InAs nanowires and single-walled carbon nanotubes. • Room temperature response is identified for isopropyl alcohol in the mixture with dry air. • Sensor response to alcohol homologs enhances with a molecule weight. • Potential platform for selective identification of different analytes and their mixtures. [ABSTRACT FROM AUTHOR]

In the research, a quantum dot (QD) under an external magnetic field is theoretically investigated. The confining potential applied to the charge carriers is chosen as the Frost-Musulin (FM) potential model. First, the energy eigenvalues and eigenstates have been analytically obtained by Nikiforov-Uvarov (NU) procedure. Then, an electric field is imposed on the system. The Stark shift effect (SSE) has been calculated and an analytical relation has been obtained in terms of the Jacobi polynomials. The findings show that the shift of electron energy states at large, and small electric fields are different. The shift is small at weak electric fields. The electron energy states decrease with the increment of the electric field. The electron states are increased by enhancing the system size. In summary, the SSE can be tuned by setting the electric field, the potential height, and the size of QD. [ABSTRACT FROM AUTHOR]

Within the framework of effective mass approximation and with the use of finite element method, we calculate the energy states of an electron in a double toroidal quantum ring with a Hopf link structure. The study includes the influence of externally applied static electric and magnetic fields, and considers different geometric combinations of radii and link positions. We have found that geometric manipulations have significant impact on the energy values and the distribution of electronic probability densities in either one or both linked rings. Similar effects can be achieved with the application of the electromagnetic probes. • Novel Hopf link quantum ring system has been modeled in finite potential barriers. • Electrical and magnetic fields tune the density probability of one confined electron. • Some geometric configurations allow overcoming the isolation of potential barriers. • Energy oscillations under magnetic field are only evident for excited states. [ABSTRACT FROM AUTHOR]

A quantitative numerical exploration is conducted to scrutinize the combined effects of size and dielectric confinement consequences on the electronic and optical characteristics of spherical multilayered quantum dot CdSe/ZnS/CdSe/ZnS (SMLQD) and its inverted configuration ZnS/CdSe/ZnS/CdSe (ISMLQD) buried into two oxides: HfO 2 and SiO 2. By employing the effective mass approximation (EMA) and the density matrix approach (DMA), the derived quantized electron energy states and their associated wave functions were obtained by solving the Schrödinger equation in a spherical coordinates. The dipole transition element, both real and imaginary parts of the effective complex dielectric function (ECDF) as well as its linear, nonlinear and total counterparts are brought out for various values of inner core radii, number density of QDs and incident photon intensity. In addition, a specific analysis of electron probability distributions is provided to gain a clearer understanding of the underlying physical factors. Our findings point to a notable influence of these mentionned factors on the computed coefficients. The study unveils that the dielectric mismatch occurring at the system/oxide interfaces plays a crucial role in modifying the electronic structure and a substantial impact on both linear and third-order nonlinear components is witnessed. • This study is focused on providing a meticulous quantitative analysis at the microscopic level, aiming to unravel the pivotal influence of surrounding oxides on a confined electron within a spherical multilayered quantum dot CdSe/ZnS/CdSe/ZnS (SMLQD) and its inverted configuration ZnS/CdSe/ZnS/CdSe (ISMLQD) buried into two oxides: HfO 2 and SiO 2. • Employing the effective mass approximation and the compact density matrix formalism, our investigation delves into the intricate interplay of inner core radius, relaxation time, number density of QDs and incident optical intensity, specifically exploring their effects on linear, third-order nonlinear and total (ECDF) as well as its real and imaginary parts. • The examination encompasses the intensities, peak locations and shifts associated with the corresponding transition under investigation. • These findings contribute to a deeper understanding of the non-linear optical behavior of quantum dot structures and offer insights into the potential applications of these nanoscale materials in advanced optical devices. [ABSTRACT FROM AUTHOR]

The group delay and dwell time are theoretically investigated in Weyl semimetals in the presence and absence of a magnetic field. The Hartman effect, which denotes the independence of group delay time on barrier length, is observed in Weyl semimetals when the incident angle and electron energy exceed certain critical values. We discuss the influence of the incident azimuthal angle, incident electron energy, and barrier length on the group delay time. Additionally, we found that the Hartman effect is also influenced by the magnetic field due to the direction dependence of the dwell time. This suggests some possible means to control the group delay time in applications involving Weyl semimetal-based devices. [ABSTRACT FROM AUTHOR]

In this study, we have calculated single-electron energy spectra via the Green’s function based on the coupled-cluster singles and doubles (GFCCSD) method for isolated atoms from H to Ne. In order to check the accuracy of the GFCCSD method, we compared the results with the exact ones calculated from the full-configuration interaction. Consequently, we have found that the GFCCSD method reproduces not only the correct quasiparticle peaks but also satellite ones by comparing the exact spectra with the 6-31G basis set. It is also found that open-shell atoms such as C atom exhibit Mott gaps at the Fermi level, which the exact density-functional theory fails to describe. The GFCCSD successfully reproduces the Mott highest-occupied molecular orbital and lowest-unoccupied molecular orbital gaps even quantitatively. We also discussed the origin of satellite peaks as shake-up effects by checking the components of wave function of the satellite peaks. The GFCCSD is a novel cutting edge to investigate the electronic states in detail. [ABSTRACT FROM AUTHOR]

In this paper, we describe an ultrafast scanning electron microscope setup developed for the research of inelastic scattering of electrons at optical near-fields of periodic dielectric nanostructures. Electron emission from the Schottky cathode is controlled by ultraviolet femtosecond laser pulses. The electron pulse duration at the interaction site is characterized via cross-correlation of the electrons with an infrared laser pulse that excites a synchronous periodic near-field on the surface of a silicon nanostructure. The lower limit of 410 fs is found in the regime of a single electron per pulse. The role of pulse broadening due to Coulomb interaction in multielectron pulses is investigated. The setup is used to demonstrate an increase in the interaction distance between the electrons and the optical near-fields by introducing a pulse-front-tilt to the infrared laser beam. Furthermore, we show the dependence of the final electron spectra on the resonance condition between the phase velocity of the optical near-field and the electron propagation velocity. The resonance is controlled by adjusting the initial electron energy/velocity and by introducing a linear chirp to the structure period allowing the increase of the final electron energy gain up to a demonstrated value of 3.8 keV. [ABSTRACT FROM AUTHOR]

In applications, surface states and bulk doping concentration are important parameters of inorganic semiconductors, as they determine the bulk properties and substantially influence the properties of interfaces in devices, foremost the electron energy level alignment. In this work, we provide a qualitative model to describe the influence of surface state density and bulk donor concentration on the work function increase upon deposition of strong organic molecular acceptors onto the surface of n-doped inorganic semiconductors. This work function increase due to electron transfer to the molecular layer has two contributions: the formation of an interface dipole and a change of the near-surface space charge region inside the inorganic semiconductor, referred to as surface band bending. By using different surface preparation methods, we show how the surface state density limits the surface band bending change and enhances the interface dipole, both measured independently by photoelectron spectroscopy. In addition, we show that bulk donor concentration variation of the inorganic semiconductor has minor influence on the ratio of the two contributions to the work function change, at least for low to moderate donor concentrations up to 1019 cm−3. [ABSTRACT FROM AUTHOR]

Probe measurements were conducted in the middle cross-section of an inductive, low-pressure xenon plasma using a straight cylindrical Langmuir probe with a bare metal shield that protected the probe from radio frequency interference. As a result, reliable radial distributions of the plasma parameters were obtained. Subsequent analyses of these measurements revealed that the electron energy distribution function (EEDF) deviated substantially from the Maxwellian functions and that this deviation depended on the length of the probe shield. To evaluate the shield's influence on the measurement results, in addition to the probe (which was moved radially as its shield length varied in the range of lsh1 = lmax–0), an additional L-shaped probe was inserted at a different location. This probe was moved differently from the first probe and provided confirmational measurements in the common special position where lsh1 = 0 and lsh2 ≠ 0. In this position, the second shield decreased all the plasma parameters. A comparison of the probe datasets identified the principles of the relationships between measurement errors and EEDF distortions caused by the bare probe shields. This dependence was used to correct the measurements performed using the first probe by eliminating the influence of its shield. Physical analyses based on earlier studies showed that these peculiarities are caused by a short-circuited double-probe effect that occurs in bare metal probe protective shields. [ABSTRACT FROM AUTHOR]

In this work, we study the argon dielectric barrier discharge with metastable atom density on capacitively coupled radio frequency at a pressure of 1 Torr. The parameter transports of argon are depending on the electron energy and their range is about of 0.04-42 eV. A one-dimensional fluid model and the drift-diffusion theory are used to describe the argon dielectric barrier discharge. The effect of the amplitude voltage on the properties of argon dielectric barrier discharge is presented on the cycle-averaged regime. Especially the electron temperature, electric potential and metastable atom density illustrate our results on figures of merits. Consequently, these quantities increase with the increasing of the amplitude voltage. Besides surface charge concentration and the gap voltage increase too. [ABSTRACT FROM AUTHOR]

A paucity of red emitting phosphors efficiently excitable in the soft UV region has been a huge barrier in solid state lighting applications from the combination of a near-UV LED exciting chip and down conversion phosphors. The present work unveils the competence of an Eu-doped yttrium pyrogermanate phosphor (Y2Ge2O7:Eu) efficiently excitable in the soft-UV region. Single phase Y2Ge2O7:Eu with 2–10% Eu content was prepared by conventional solid-state reaction and thoroughly characterized using XRD, FTIR, RAMAN and XPS techniques. To examine the potential of the Y2Ge2O7:Eu phosphor, its photoluminescence behavior was compared with standard commercial red phosphor Y2O3:Eu. Remarkably, the results reveal that Y2Ge2O7:Eu retains the pros of the commercial phosphor and compensates for its cons. Whilst the emission profile, decay lifetime and internal quantum efficiency of Y2Ge2O7:Eu are almost identical to those of Y2O3:Eu, its Eu-incorporation capacity without concentration quenching is as high as 10% contrary to 5–6% of Y2O3:Eu owing to the less dense distribution of Y-sites in the Y2Ge2O7 host. High loading of Eu-content makes Y2Ge2O7:Eu suitable for high contrast displays. Whereas the Y2O3:Eu phosphor has negligible absorption efficiency in the soft UV region, the Y2Ge2O7:Eu phosphor has its maximum absorption efficiency around 390 nm nicely aligned with the emission of near UV LED chips. DFT calculations revealed that relatively deeper positioning of the Y2Ge2O7 valence electron energy states and associated covalency are decisive for its demonstration of competing performance. Successful dispersion of Y2Ge2O7:Eu inside a polymer matrix further endorses its potential towards future flexible device applications. [ABSTRACT FROM AUTHOR]

Miniature ion thrusters are an attractive option for a wide range of space missions due to their low power levels and high specific impulse. Thrusters using ring-cusp plasma discharges promise the highest performance, but are still limited by the challenges of efficiently maintaining a plasma discharge at such small scales (typically 1-3 cm diameter). This effort significantly advances the understanding of miniature-scale plasma discharges by comparing the performance and xenon plasma confinement behavior for 3-ring, 4-ring, and 5-ring cusp by using the 3 cm Miniature Xenon Ion thruster as a modifiable platform. By measuring and comparing the plasma and electron energy distribution maps throughout the discharge, we find that miniature ring-cusp plasma behavior is dominated by the high magnetic fields from the cusps; this can lead to high loss rates of high-energy primary electrons to the anode walls. However, the primary electron confinement was shown to considerably improve by imposing an axial magnetic field or by using cathode terminating cusps, which led to increases in the discharge efficiency of up to 50%. Even though these design modifications still present some challenges, they show promise to bypassing what were previously seen as inherent limitations to ring-cusp discharge efficiency at miniature scales. [ABSTRACT FROM AUTHOR]

If an electron beam is periodically modulated in velocity, for example by laser field cycles, it can transform upon further propagation into a train of attosecond or shorter electron pulses. Here, I investigate the quantum mechanics of such an approach by numerically solving the Schrödinger equation in the time domain. There is a limit for the shortest electron pulses that can be achieved, and it depends on simple relations between the electron energy, the laser period, and the modulation strength. These results allow to design future experiments and to compare the measured electron pulse shapes to their quantum limit. [ABSTRACT FROM AUTHOR]

We present a set of neural network models that reproduce the dynamics of electron fluxes in the range of 50 keV ∼1 MeV in the outer radiation belt. The Outer Radiation belt Electron Neural net model for Medium energy electrons uses only solar wind conditions and geomagnetic indices as input. The models are trained on electron flux data from the Magnetic Electron Ion Spectrometer instrument onboard Van Allen Probes, and they can reproduce the dynamic variations of electron fluxes in different energy channels. The model results show high coefficient of determination (R2 ∼ 0.78–0.92) on the test data set, an out‐of‐sample 30‐day period from 25 February to 25 March in 2017, when a geomagnetic storm took place, as well as an out‐of‐sample one year period after March 2018. In addition, the models are able to capture electron dynamics such as intensifications, decays, dropouts, and the Magnetic Local Time dependence of the lower energy (∼<100 keV) electron fluxes during storms. The models have reliable prediction capability and can be used for a wide range of space weather applications. The general framework of building our model is not limited to radiation belt fluxes and could be used to build machine learning models for a variety of other plasma parameters in the Earth's magnetosphere. Plain Language Summary: The Earth's radiation belts consist of energetic particles trapped by the geomagnetic field. This radiation environment is known to be particularly hazardous to spacecrafts and difficult to predict given the complex dynamics of electrons at different energy states. This paper presents a set of neural‐network‐based models that use measurements of geomagnetic and solar activities as drivers to reconstruct radiation belt electron fluxes ranging from 50 keV to 1 MeV. The models can determine the flux with high accuracy and capture the electron dynamics with long‐ and short‐term time scales. The models provide reliable prediction capability and can be used for a wide range of space weather applications. The approach through which our models are built is not limited to radiation belt fluxes and can be generalized for a variety of other plasma parameters in the Earth's magnetosphere. Key Points: A set of neural network models was developed to reconstruct the 50 keV‐1 MeV electron fluxes in the outer radiation beltThe models reproduce fluxes with a high overall accuracy (R2 ∼ 0.78–0.92) during out‐of‐sample periods, including long‐ and short‐term dynamicsThe models reproduce the time‐varying Magnetic Local Time dependence exhibited during storms by the lower energy electrons (∼<100 keV) [ABSTRACT FROM AUTHOR]

In this work, we present the new photodetector based on snowflake quantum rings (QRs) structure utilizing a two-dimensional tight-binding model. Optical absorption has calculated and compared with different usual geometries of rectangular, triangular and circular QRs. There are narrow dominant peaks in the absorption spectrum with a low FHWM of 15 meV in the range of 50 meV in the far-infrared (FIR) regime to 300 meV in the mid-infrared (FIR) regime. The two-dimensional confining potential for Koch shaped quantum ring had been described in previous work was inserted in the tight-binding method and probability density of nine lowest electron energy states and absorption have calculated for the first time. Using these results, some properties of QRs were predicted and their validity was examined and displayed further. For a Koch shape quantum ring, there is fine displacement about 3 meV in absorption peak in long-wavelength infrared regime with changing iteration number that can be used for fine-tuning of the absorption spectrum. Also, a circular ring with minimal energy states has absorption peaks with an average full width at half maximum of 12.5 meV that can be tuned with the resolution of 13 meV in the FIR regime. These results are more applicable for an experimentalist to design a new photodetector with a narrower sharp peak for applications like night-vision, a thermal detector, and total IR absorbers. [ABSTRACT FROM AUTHOR]

Semiconductor quantum dots, due to their unique optical properties, are promising materials for the design of optoelectronic devices. At the same time, the parameters of instruments significantly depend both on the band structure and the impurity energy levels in quantum dots. In this regard, the electron–phonon interaction acts as the most important mechanism of temperature shift in energy levels. The aim of the present work was to theoretically study how the electron–phonon interaction influences the temperature dependence of radiative recombination in an impurity complex in a semiconductor quasi-zero-dimensional structure. The effect of temperature on the energy levels in a semiconductor quantum dot was theoretically considered by the statistics method assuming that the electron–phonon interaction makes the main contribution to the temperature dependence. The dispersion equation defining the hole binding energy in the impurity complex in a spherically symmetric quantum dot was obtained in terms of the adiabatic approximation in the zero-range potential model. The spectral intensity of recombination radiation in the quasi-zero-dimensional structure with impurity complexes was calculated in the dipole approximation taking into account the radius dispersion of quantum dots. Temperature curves were plotted for the case of InSb-based quantum dots. The temperature dependence of the binding energy in the complex was calculated for different values of the quantum-dot radius. The hole binding energy was shown to decrease with an increase in temperature, which was due to a temperature spreading of the wave function of a quasi-steady A+ state under the conditions of electron–phonon and hole–phonon interactions. The bond energy of the A+ state was found to increase with a decrease in the quantum-dot radius due to an increase in the ground state energy of the adiabatic electron potential. The spectral intensity of recombination radiation was calculated as a function of the transition energy for different temperature values. It was found that, with an increase in temperature, the threshold transition energy shifts to the short-wave spectral region and thermal quenching of the recombination radiation occurs. This was due to a decrease in the overlap integral of the wave functions of initial and final electron states because of the transition energy increase. The effect of the electron–phonon interaction on recombination processes in the impurity complex in spherically symmetric quantum dot is manifested in temperature quenching of the recombination radiation spectral intensity. The effect of coming to a plateau appears to be common for different mechanisms of photoluminescence. [ABSTRACT FROM AUTHOR]

In this study, a detailed investigation was done on the effects of changing the position of a donor impurity on the electronic and optical properties of an electron confined within a fixed size wurtzite (WZ) ZnS/ZnO/ZnS multishell quantum dot. We carried out the calculation using the framework of the effective mass approximation (EMA), relying entirely upon the non-degenerate quantum perturbation theory, using the unperturbed impurity-less eigenstates as expansion states. We computed the binding energy for the ground state and several other excited states as well as the transition dipole moment (TDM) along the z-direction for multiple electron state transitions. Finally, we concluded by computing the absorption coefficient for multiple transitions using perturbed electron states energy and transition dipole moments. The results show that the position of the donor impurity does have an impact on the electronic and optical properties of the confined electron. [ABSTRACT FROM AUTHOR]

To meet the high energy demand of society, a conversion to renewable energy sources has become essential and energy should be appropriately stored for future use. This has led to the development of energy-storing devices such as supercapacitors (SCs). To enhance capacitive behavior, the concept of quantum capacitance (C Q) is unveiled, which results from the confinement of electrons in their energy states. In this work, 1T phase of MoS 2 is studied as it has received a lot of attention because of its wide applications in the energy storage devices and electronics. Here, the electronic structure, C Q and surface charge density (σ) of one, two and three-layered structures of 1T phase is studied using Density Functional Theory. No bandgap is obtained in the Density of States (DOS) and the bands plot of 1T structure indicates their metallic character and the DOS is continuous in all three layers. The C Q of three-layered structure dominates over the other two layers throughout the potential window. The larger C Q and σ values are obtained as 1718.06 μF cm−2 and -1299.50 μC cm−2 for three-layered structure at −0.27 V and −1 V respectively. For analyzing the mechanical strength, Young's modulus is evaluated for optimized structure by applying uni-axial strain. The value is obtained as 177.37 GPa, which is a measure of elastic deformation behavior. The results suggest that the capacitive performance of 1T MoS 2 for SC applications is better and it can function as flexible cathode material for asymmetric SC applications. [ABSTRACT FROM AUTHOR]

We present theoretical simulations of electron refraction at the lateral atomic interface between a "homogeneous" Cu(111) surface and the "nanostructured" one-monolayer (ML) Ag/Cu(111) dislocation lattice. Calculations are performed for electron binding energies barely below the 1 ML Ag/Cu(111) M-point gap (binding energy EB = 53 meV, below the Fermi level) and slightly above its Γ-point energy (EB = 160 meV), both characterized by isotropic/circular constant energy surfaces. Using plane-wave-expansion and boundary-element methods, we show that electron refraction occurs at the interface, the Snell law is obeyed, and a total internal reflection occurs beyond the critical angle. Additionally, a weak negative refraction is observed for EB = 53 meV electron energy at beam incidence higher than the critical angle. Such an interesting observation stems from the interface phase-matching and momentum conservation with the umklapp bands at the second Brillouin zone of the dislocation lattice. The present analysis is not restricted to our Cu-Ag/Cu model system but can be readily extended to technologically relevant interfaces with spin-polarized, highly featured, and anisotropic constant energy contours, such as those characteristic for Rashba systems and topological insulators. [ABSTRACT FROM AUTHOR]

We use the one-dimensional object-oriented particle-in-cell Monte Carlo collision code oopd1 to explore the charged particle densities, the electronegativity, the electron energy probability function, and the electron heating mechanism in a single frequency capacitively coupled oxygen discharge, when the applied voltage amplitude is varied. We explore discharges operated at 10 mTorr, where electron heating within the plasma bulk (the electronegative core) dominates, and at 50 mTorr, where sheath heating dominates. At 10 mTorr, the discharge is operated in a combined drift-ambipolar and α-mode, and at 50 mTorr, it is operated in the pure α-mode. At 10 mTorr, the effective electron temperature is high and increases with increased driving voltage amplitude, while at 50 mTorr, the effective electron temperature is much lower, in particular, within the electronegative core, where it is roughly 0.2-0.3 eV, and varies only a little with the voltage amplitude. [ABSTRACT FROM AUTHOR]

Our high-resolution electron energy-loss measurements concern physisorbed H2 and comprise differential cross sections for the excitation of the internal H2 modes and the 2-surface bonding mode and their combinations and extend over the electron impact energy range of the classical low-energy 2 2Σu resonance. Comparison with corresponding data for the excitation of the internal modes of gas phase H2 reveals that strong elastic electron reflectivity from the Cu(100) substrate profoundly distorts the inelastic scattering pattern for physisorbed 2.We find that this influence can be corrected for and that the resulting peak cross sections agree with the 2 gas phase data, in accordance with theoretical predictions for the excitation of the internal 2 vibration. We have used corrected cross sections for the rotational mode spectra of physisorbed 2, HD, and 2 in a model concerning electron induced desorption via rotation-translation energy conversion. These spectra include transitions from the ground state as well as excited levels of the physisorption potential well. 2 and HD can desorb from all levels while D2, for energetic reason, can only desorb from the excited levels. This model gives a satisfactory account of the observed desorption cross sections and predicts characteristic velocity distributions of the desorbing molecules. The cross section data for H2 and HD reveals that direct bound-free transitions also contribute to the electron induced desorption. [ABSTRACT FROM AUTHOR]

Dissociative electron attachment to nicotine, pyridine, and N-methyl-pyrrolidine was studied in the gas phase in order to assess their stability with respect to low-energy electron interactions. Anion yield curves for different products at electron energies ranging from zero to 15 eV were measured, and the molecular fragmentation pathways were proposed. Nicotine does not form a stable parent anion or a dehydrogenated anion, contrary to other biological systems. However, we have observed complex dissociation pathways involving fragmentation at the pyrrolidine side accompanied by isomerization mechanisms. Combining structure optimization and enthalpy calculations, performed with the Gaussian09 package, with the comparison with a deuterium-labeled N-methyl-d3-pyrrolidine allowed for the determination of the fragmentation pathways. In contrast to nicotine and N-methylpyrrolidine, the dominant pathway in dissociative electron attachment to pyridine is the loss of hydrogen, leading to the formation of an [M--H] anion. The presented results provide important new information about the stability of nicotine and its constituent parts and contribute to a better understanding of the fragmentation mechanisms and their effects on the biological environment. [ABSTRACT FROM AUTHOR]

An approach for the construction of vibronically coupled potential energy surfaces describing reactive collisions is proposed. The scheme utilizes neural networks to obtain the elements of the diabatic potential energy matrix. The training of the neural network employs a diabatization by the Ansatz approach and is solely based on adiabatic electronic energies. Furthermore, no system-specific symmetry consideration is required. As the first example, the H2 + Cl → H + HCl reaction, which shows a conical intersection in the entrance channel, is studied. The capability of the approach to accurately reproduce the adiabatic reference energies is investigated. The accuracy of the fit is found to crucially depend on the number of data points as well as the size of the neural network. 5000 data points and a neural network with two hidden layers and 40 neurons in each layer result in a fit with a root mean square error below 1 meV for the relevant geometries. The coupled diabatic potential energies are found to vary smoothly with the coordinates, but the conical intersection is erroneously represented as a very weakly avoided crossing. This shortcoming can be avoided if symmetry constraints for the coupling potential are incorporated into the neural network design. [ABSTRACT FROM AUTHOR]

We have studied the color-center production in sapphire and yttria-stabilized zirconia (YSZ) single crystals by cathodo-luminescence (CL) spectroscopy for electron energies ranging between 400 and 1250 keV in a high-voltage electron microscope. Emission spectra were collected for in-beam conditions near room temperature and at 200 K. Comparison was made with CL spectra recorded for 3-keV-20-keV electrons in a scanning electron microscope. For high-energy electrons, CL spectra for sapphire revealed broad emission bands centered at photon energies about 3.0 eV and 3.8 eV that were, respectively, assigned to oxygen vacancies (F0 and F+ centers) induced by elastic collisions, on the basis of photoluminescence (PL) data. No such bands were recorded for 3-keV and 5-keV electrons. Two similar bands were also recorded for YSZ (with 9.5 and 18 mol. % yttria) at about 2.8 eV and 4.1 eV that can be, respectively, attributed to the native oxygen vacancies (F2+ centers) and F+ centers. The 4.1-eV band was not seen for 20-keV electrons: it was only produced for high electron energies by elastic collision processes. Instead, the small side band was also found at 2.85 eV for 20-keV electrons. PL excitation contour plots of virgin and irradiated YSZ were also recorded to support our discussion on point-defect identification. CL band intensities show a maximum versus electron energy, whereas point-defect concentrations should increase due to the increase of oxygen atom displacement cross section. The effect of electron energy on the different steps of the CL process is discussed to account for such a behavior. [ABSTRACT FROM AUTHOR]