Electron Kinetic Energy Research Articles

Experimental Realization of Auger Decay in the Field of a Positive Elementary Charge.

Auger electron spectroscopy is an omnipresent experimental tool in many fields of fundamental research and applied science. The determination of the kinetic energies of the Auger electrons yields information about the element emitting the electron and its chemical environment at the time of emission. Here, we present an experimental approach to determine Auger spectra for emitter sites in the vicinity of a positive elementary charge based on electron-electron-electron and electron-electron-photon coincidence spectroscopy. We observe a characteristic redshift of the Auger spectrum caused by the Coulomb interaction with the charged environment. Our results are relevant for the interpretation of Auger spectra of extended systems like large molecules, clusters, liquids, and solids, in particular in high-intensity radiation fields which are nowadays routinely available, e.g., at x-ray free-electron laser facilities. The effect has been widely ignored in the literature so far, and some interpretations of Auger spectra from clusters might need to be revisited.

Triboelectric Basalt Textiles Efficiently Operating within an Ultrawide Temperature Range.

With the continuous upsurge in demand for wearable energy, nanogenerators are increasingly required to operate under extreme environmental conditions. Even though they are at the cutting edge of technology, nanogenerators have difficulty producing high-quality electrical output at very extreme temperatures. Here, a triboelectric basalt textile (TBT) with an ultrawide operational temperature range (from -196 to 520°C) is created employing basalt material as the main body. The output power density of the TBT, in contrast to most conventional nanogenerators, would counterintuitively rise by 2.3 times to 740.6mW m-2 after heating to 100°C because the high temperature will enhance the material's interface polarization and electronic kinetic energy. The TBT retains ≈55% of its initial electrical output even after heating in the flame of an alcohol lamp (520°C). Surprisingly, the TBTs output voltage may retain over 85% of its initial value even after submerging in liquid nitrogen. The TBTs exceptional resistance to heat and cold indicates its possible use in high and low latitudes, high altitudes, deserts, and even space settings.

Solar neutrino measurements using the full data period of Super-Kamiokande-IV

An analysis of solar neutrino data from the fourth phase of Super-Kamiokande (SK-IV) from October 2008 to May 2018 is performed and the results are presented. The observation time of the dataset of SK-IV corresponds to 2970 days and the total live time for all four phases is 5805 days. For more precise solar neutrino measurements, several improvements are applied in this analysis: lowering the data acquisition threshold in May 2015, further reduction of the spallation background using neutron clustering events, precise energy reconstruction considering the time variation of the PMT gain. The observed number of solar neutrino events in 3.49–19.49 MeV electron kinetic energy region during SK-IV is 65,443−388+390(stat.)±925(syst.) events. Corresponding B8 solar neutrino flux is (2.314±0.014(stat.)±0.040(syst.))×106 cm−2 s−1, assuming a pure electron-neutrino flavor component without neutrino oscillations. The flux combined with all SK phases up to SK-IV is (2.336±0.011(stat.)±0.043(syst.))×106 cm−2 s−1. Based on the neutrino oscillation analysis from all solar experiments, including the SK 5805 days dataset, the best-fit neutrino oscillation parameters are sin2θ12,solar=0.306±0.013 and Δm21,solar2=(6.10−0.81+0.95)×10−5 eV2, with a deviation of about 1.5σ from the Δm212 parameter obtained by KamLAND. The best-fit neutrino oscillation parameters obtained from all solar experiments and KamLAND are sin2θ12,global=0.307±0.012 and Δm21,global2=(7.50−0.18+0.19)×10−5 eV2. Published by the American Physical Society 2024

Derivation of the Schrödinger equation from QED

The Schrödinger equation relates the emergent quantities of wavefunction and electric potential and is postulated as a principle of quantum physics or obtained heuristically. However, physical consistency requires that the Schrödinger equation is a low-energy dynamical condition we can derive from the foundations of quantum electrodynamics. Due to the small value of the electromagnetic coupling constant, we show that the electric potential accurately represents the contributions of intermediate low-energy photon exchanges. Then, from the total nonrelativistic energy relation, we see that the dominant term of the electron wavefunction is a superposition of plane waves that satisfies the Schrödinger equation. Our derivation shows that the Schrödinger equation is not an energy conservation relation because its middle term does not represent the electron kinetic energy as assumed. We analyze the physical content of the Schrödinger equation and verify our assessments by calculating and evaluating the physical quantities in the ground state of the hydrogen atom. Furthermore, we explain why nonrelativistic quantum dynamics differs from classical dynamics. Undergraduate students can follow the derivation because it involves fundamental physical concepts and mathematical expressions, and we explain every step.

Gamma-ray, fast neutron and charged particle shielding performance of 15Li2O-25BaO-(40-x)B2O3-20P2O5-xDy2O3 glass system

Gamma-ray, fast neutron and charged particle shielding characteristics of Dy3＋ activated glasses with composition 15Li2O-25BaO-(40-x)B2O3-20P2O5-xDy2O3 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0 mol%) are analyzed in a wide incident energy for the first time. For gamma-ray shielding analysis, mass attenuation coefficient (MAC), mass energy absorption coefficient (μen), linear attenuation coefficient (LAC), mean free path (MFP), half-value layer (HVL), atomic cross-section (ACS), electronic cross-section (ECS), effective atomic number (Zeff), equivalent atomic number (Zeq), effective conductivity (Ceff), effective electron density (Neff), buildup factors (EABF and EBF), and kinetic energy released per unit mass of the absorbing material (KERMA) are calculated by using Phy-X/PSD and PAGEX softwares. For fast neutrons, fast neutron removal cross-section (FNRCS) is computed for all glass samples. For charged particle shielding analysis, mass stopping power (MSP), projected range (Rp), radiation yield (Ry), Zeff and Neff are computed using SRIM, ESTAR and PAGEX softwares. It is found that the glasses with increasing Dy3＋ have higher shielding potential. This suggests that the LBPDy1.0 sample has a potential use as shielding material for various applied fields.

Anomalous electrons in a metallic kagome ferromagnet

Ordinary metals contain electron liquids within well-defined ‘Fermi’ surfaces at which the electrons behave as if they were non-interacting. In the absence of transitions to entirely new phases such as insulators or superconductors, interactions between electrons induce scattering that is quadratic in the deviation of the binding energy from the Fermi level. A long-standing puzzle is that certain materials do not fit this ‘Fermi liquid’ description. A common feature is strong interactions between electrons relative to their kinetic energies. One route to this regime is special lattices to reduce the electron kinetic energies. Twisted bilayer graphene1–4 is an example, and trihexagonal tiling lattices (triangular ‘kagome’), with all corner sites removed on a 2 × 2 superlattice, can also host narrow electron bands5 for which interaction effects would be enhanced. Here we describe spectroscopy revealing non-Fermi-liquid behaviour for the ferromagnetic kagome metal Fe3Sn2 (ref. 6). We discover three C3-symmetric electron pockets at the Brillouin zone centre, two of which are expected from density functional theory. The third and most sharply defined band emerges at low temperatures and binding energies by means of fractionalization of one of the other two, most likely on the account of enhanced electron–electron interactions owing to a flat band predicted to lie just above the Fermi level. Our discovery opens the topic of how such many-body physics involving flat bands7,8 could differ depending on whether they arise from lattice geometry or from strongly localized atomic orbitals9,10.

Laboratory observation of electron energy distribution near three-dimensional magnetic nulls

The acceleration of electrons near three-dimensional (3D) magnetic nulls is crucial to the energy conversion mechanism in the 3D magnetic reconnection process. To explore electron acceleration in a 3D magnetic null topology, we constructed a pair of 3D magnetic nulls in the PKU Plasma Test (PPT) device and observed acceleration of electrons near magnetic nulls. This study measured the plasma floating potential and ion density profiles around the 3D magnetic null. The potential wells near nulls may be related to the energy variations of electrons, so we measured the electron distribution functions (EDFs) at different spatial positions. The axial variation of EDF shows that the electrons deviate from the Maxwell distribution near magnetic nulls. With scanning probes that can directionally measure and theoretically analyze based on curve fitting, the variations of EDFs are linked to the changes of plasma potential under 3D magnetic null topology. The kinetic energy of electrons accelerated by the electric field is 6 eV ( ) and the scale of the region where accelerating electrons exist is in the order of serval electron skin depths.

Surface engineering of Ag3PO4 using lithium iodide for enhanced photocatalytic activity

The surface engineering of Ag3PO4 using lithium iodide was successfully carried out to induce photocatalytic properties. The Ag3PO4 surface was treated using a lithium iodide solution from low to high concentration under stirring and continued with aging. The modified Ag3PO4 samples were characterized using XRD, SEM, BET, UV–Vis DRS, PL spectra, TRPL, Raman spectra, and XPS. LiI treatment on the Ag3PO4 surface decreases a symmetric stretching [PO4] tetrahedron, P/Ag atomic ratio, and FWHM of Ag3d and P2p, and increases the kinetic energy of AgMNN Auger electrons. These phenomena were due to the incorporation of iodine on the Ag3PO4 surface and defect formation on the Ag3PO4 surface. Treatment with a low concentration of LiI solution showed higher photocatalytic activity with a rate constant of 9.05 times faster than samples without LiI treatment. The high photocatalytic activity was due to the suppression of hole and electron recombination, stronger hole species, and high adsorption on the surface of Ag3PO4.

Study on the Effect of Cations on the Surface Energy of Nano-SiO2 Particles for Oil/Gas Exploration and Development Based on the Density Functional Theory.

Although nano SiO2 exhibits excellent application potential in the field of oil and gas exploration and development, such as drilling fluid, enhanced oil/gas recovery, etc., it is prone to agglomeration and loses its effectiveness due to the action of cations in saline environments of oil and gas reservoirs. Therefore, it is crucial to study the mechanism of the change in energy between nano SiO2 and cations for its industrial application. In this paper, the effect of cations (Na+, K+, Ca2+, and Mg2+) on the surface energy of nano SiO2 particles is investigated from the perspective of molecular motion and electronic change by density functional theory. The results are as follows: Due to the electrostatic interactions, cations can migrate towards the surface of nano SiO2 particles. During the migration process, monovalent cations are almost unaffected by water molecules, and they can be directly adsorbed on the surface by nano SiO2 particles. However, when divalent cations migrate from a distance to the surface of nano SiO2 particles, they can combine with water molecules to create an energy barrier, which can prevent them from moving forward. When divalent cations break through the energy barrier, the electronic kinetic energy between them and nano SiO2 particles changes more strongly, and the electrons carried by them are more likely to break through the edge of the atomic nucleus and undergo charge exchange with nano SiO2 particles. The change in interaction energy is more intense, which can further disrupt the configuration stability of nano SiO2. The interaction energy between cations and nano SiO2 particles mainly comes from electrostatic energy, followed by Van der Waals energy. From the degree of influence of four cations on nano SiO2 particles, the order from small to large is as follows: K+ < Na+ < Mg2+ < Ca2+. The research results can provide a theoretical understanding of the interaction between nano SiO2 particles and cations during the application of nano SiO2 in the field of oil and gas exploration and development.

Spotlight: Visualization of Moiré Quantum Phenomena in Transition Metal Dichalcogenide with Scanning Tunneling Microscopy.

Transition metal dichalcogenide (TMD) moiré superlattices have emerged as a significant area of study in condensed matter physics. Thanks to their superior optical properties, tunable electronic band structure, strong Coulomb interactions, and quenched electron kinetic energy, they offer exciting avenues to explore correlated quantum phenomena, topological properties, and light-matter interactions. In recent years, scanning tunneling microscopy (STM) has made significant impacts on the study of these fields by enabling intrinsic surface visualization and spectroscopic measurements with unprecedented atomic scale detail. Here, we spotlight the key findings and innovative developments in imaging and characterization of TMD heterostructures via STM, from its initial implementation on the in situ grown sample to the latest photocurrent tunneling microscopy. The evolution in sample design, progressing from a conductive to an insulating substrate, has not only expanded our control over TMD moiré superlattices but also promoted an understanding of their structures and strongly correlated properties, such as the structural reconstruction and formation of generalized two-dimensional Wigner crystal states. In addition to highlighting recent advancements, we outline upcoming challenges, suggest the direction of future research, and advocate for the versatile use of STM to further comprehend and manipulate the quantum dynamics in TMD moiré superlattices.

Quantum fundaments of catalysis: true electronic potential energy.

Catalysis is a quantum phenomenon enthalpically driven by electronic correlations with many-particle effects in all of its branches, including electro-photo-catalysis and electron transfer. This means that only probability amplitudes provide a complete relationship between the state of catalysis and observations. Thus, in any atomic system material), competing space-time electronic interactions coexist to define its (related) properties such as stability, (super)conductivity, magnetism (spin-orbital ordering), chemisorption and catalysis. Catalysts, reactants, and chemisorbed and transition states have the possibility of optimizing quantum correlations to improve reaction kinetics. Active sites with closed-shell orbital configurations share a maximum number of spin-paired electrons, mainly optimizing coulombic attractions and covalency and defining weakly correlated closed-shell (WCCS) structures. However, in compositions with open-shell orbital configurations, at least, quantum spin exchange interactions (QSEIopenshells) arise, stabilising unpaired electrons in less covalent bonds and differentiating non-weakly (or strongly) correlated open-shell (NWCOS) systems. In NWCOS catalysts, electronic ground states can have bonds with diverse and rival spin-orbital orderings as well as ferro-, ferri- and multiple antiferro-magnetic textures, which deeply define their activities. Particularly in inter-atomic ferromagnetic (FM) bonds, the increase in relevance of non-classical quantum potentials can significantly optimize chemisorption energies, transition states (TSs), activation energies (overpotential) and spin-dependent electron transfer (conductivity), overall implying the need for explaining the thermodynamic and kinetic origin of catalysis from its true quantum electronic energy. To do so, we use the connection between the Born-Oppenheimer approximation and Virial theorem in the treatment of electronic kinetic and potential energies. Thus, the exact fundamental interactions that decompose TSs appear. The possibility of increasing the stabilization of TSs, due to quantum correlations on NWCO catalysts, opens the possibility of simultaneously reducing chemisorption enthalpies and activation barriers of reaction mechanisms, which implies the anticipation and explanation of positive deviations from the Brønsted-Evans-Polanyi principle.

Ultrafast electron dynamics in excited states of conjugated thiophene-fluorene organic polymer (pF8T2) thin films.

The electronic states of poly(9,9-dioctylfluorenyl-alt-bithiophene) pF8T2 on H/Si(100) substrates, prototypical for organic photovoltaics, were investigated by ultrafast photoelectron spectroscopy and by time-resolved fluorescence studies. Occupied and unoccupied electronic states were analysed by ultraviolet photoelectron spectroscopy (UPS), static and dynamic femtosecond two-photon photoemission (2PPE), and time-correlated single photon counting (TCSPC). Time-resolved measurements allow assessment of population lifetimes of intermediate states. The combination of time-resolved photoelectron spectroscopy and fluorescence excitation allows following the electronic dynamics in excited states from the femtosecond to the nanosecond time scale. For this prototypical material the electron kinetic energy resolved lifetimes range from about a few tens of femtoseconds up to hundreds of picoseconds. After annealing these types of organic thin films the efficiency of organic solar cells usually increases. We show that annealing does not influence the initial ultrafast charge generation processes, but the long-lived states. However, the nanosecond scale fluorescence lifetimes measured by TCSPC are prolonged after annealing, which therefore is identified as the cause of a greater exciton diffusion range and thus is beneficial for charge carrier extraction.

A Modeling Study of Electron Transport in GaN/AlGaN Superlattices Using Monte Carlo Simulation

Electron transport in superlattices (SLs) is analyzed using a single‐particle Monte Carlo (MC) method. This study includes the band structure of GaN, AlN, and their alloys, utilizing a single‐electron MC approach and a three‐band model. It explores how intervalley (IV) and electron–polar longitudinal optical phonon (PLOP) scatterings influence electron velocity. A single non‐parabolic band approximation is effectively used in SL modeling, as the miniband's energy width limits electron kinetic energy, reducing IV scattering. The energy band structure of the SL is calculated using the Schrödinger equation and a Poisson solver, incorporating a single‐band model to determine the Fermi energy and characteristics of the SL miniband. Miniband dispersion is evaluated using an effective mass approximation at low energies and a non‐parabolicity factor at higher energies. The MC method is then applied to study electron transport within the miniband, revealing that for SLs with low Al content and short periods, electron behavior resembles that in bulk GaN. It is observed that negative differential mobility can occur, attributed to electron–PLOP scattering and non‐parabolicity. This approach offers a quick and effective way to research high‐field electron transport in n‐doped SLs, aiding in device design.

The work of the olfactory cell

Work is the basic physical quantity that determines the amount of energy needed to perform a given task. In the case of smell, it is a complex process of receiving odor signals from the outside world, transforming them in the olfactory cell into the form of chemical bonding energy, which is converted into electrical energy of the action potential at the synapse between the I and II neurons of the olfactory pathway. Regardless of the many transformations of energy along the way, the signal reaching the brain must be recognizable in quality and intensity. The olfactory organ works around the clock, although olfactory sensations do not reach the brain at night. Very strong odors like ammonia can wake you from sleep. The entire system uses external energy to perform work. Similar to the nerve cell and the auditory cell, the olfactory cell is an excitable cell, meaning that the action of an external stimulus leads to a response in the form of depolarization of the cell. A bidirectional action of the cell is created. In addition to the normal work related to the life of the cell - like with any other cell, for that matter, there is work related to the transformation of the olfactory signal in the cell and the transmission of this signal to the synapse. These two levels of olfactory cell activity are closely related, dependent on each other, using the same substrates and frequently the same transmission pathways. The level related to cell life is the constitutive level, while the second level, related to signal transmission, is the regulated level. This latter level begins with taking over the energy of odor substance - an odorant, which, regardless of its size, has kinetic energy, potential energy and electron energy. By binding with the GPCR receptor and acceptor, the odorant causes the transfer of some of its own energy, that associated with the odor. The electron cloud of the odorant, after combining with the electron cloud of the receptor, loses a certain amount of electrons or protons. After transmitting information to the acceptor, such a molecule is detached from the receptor and enzymatically destroyed. OBP is just an intermediary for these reactions. Further transformations of the energy of the olfactory signal take place in the cell and synapse.

Nonthermal effects in solids after swift heavy ion impact

This contribution is a brief introduction to nonthermal effects related to modifications of the interatomic potential upon ultrafast excitation of the electronic system of solids, primarily focusing on the swift heavy ion track problem. We clarify the difference between the exchange of the kinetic energy of electrons (and holes) scattering on the lattice (electron–phonon coupling, “thermal effects”) and the relaxation of the nonequilibrium potential energy of a solid (“nonthermal effects”). We discuss that at different degrees of electronic excitation, the modification of the interatomic potential may result in various phase transitions without an increase of the atomic temperature, i.e., at room temperature (nonthermal melting, formation of the superionic state), or in atomic acceleration causing “nonthermal heating” of the target atoms. Examples of various theoretically predicted effects are given, supported by known experimental observations.

Peculiarities of Electron Transport through the Contact Regions between Semiconductor Quantum Wires with Different Cross Sections

In present work peculiarities of electron transport with transition from quantum wires with smaller cross sections to quantum wires with larger cross sections are studied. Electron transition probabilities through corresponding contact regions of such quantum wires are calculated as functions of charge carrier kinetic energy and quantum wire cross sections ratio. Peculiarities of electron pass through the defects in quantum wires in the form of rectangular grooves and steps are also studied. Electron transition probabilities through the defect regions are calculated as functions of electron kinetic energy and geometry and size of the defects. Probability density distributions of electron detection in different regions of simulated structures have been calculated.

Velocity-space Signatures of Resonant Energy Transfer between Whistler Waves and Electrons in the Earth’s Magnetosheath

Wave–particle interactions play a crucial role in transferring energy between electromagnetic fields and charged particles in space and astrophysical plasmas. Despite the prevalence of different electromagnetic waves in space, there is still a lack of understanding of fundamental aspects of wave–particle interactions, particularly in terms of energy flow and velocity-space characteristics. In this study, we combine a novel quasilinear model with observations from the Magnetospheric Multiscale mission to reveal the signatures of resonant interactions between electrons and whistler waves in magnetic holes, which are coherent structures often found in the Earth’s magnetosheath. We investigate the energy transfer rates and velocity-space characteristics associated with Landau and cyclotron resonances between electrons and slightly oblique propagating whistler waves. In the case of our observed magnetic hole, the loss of electron kinetic energy primarily contributes to the growth of whistler waves through the n = −1 cyclotron resonance, where n is the order of the resonance expansion in linear Vlasov–Maxwell theory. The excitation of whistler waves leads to a reduction of the temperature anisotropy and parallel heating of the electrons. Our study offers a new and self-consistent understanding of resonant energy transfer in turbulent plasmas.

P(VDF-HFP)-based nanocomposites with elaborative PN-junction nanofillers displaying high energy storage performance

Given its wide application ranges, dielectric capacitors have garnered extensive attentions. However, due to the excessive premature agglomeration of free electrons, capacitors with nanocomposites as dielectrics fail to attain high breakdown strength (Eb), and thereby constrain their ability to achieve superior energy storage performances. To alleviate the effects of free electrons and secondary impact-ionized electrons (SIE) on Eb and leakage currents, here, a novel organic-inorganic core–shell Ni(OH)2@PDI (N@P) nanofiller with opposite double-PN-junction was well-designed and successfully synthesized by coating p-typed Ni(OH)2 nanosheets with n-typed perylene diimide (PDI). It could reduce free electron kinetic energy and mitigate SIE amounts regardless of the applied electric field direction. Furthermore, PDI, as an organic compound, can uniformly and densely coat onto surfaces of 2D Ni(OH)2, as well as enhance compatibilities between Ni(OH)2 and matrix, and thereby reducing structure defects at their interfaces. Last but not the least, Ni(OH)2 nanosheets also contribute to Eb improvement via acting as scattering centers. Experimental and simulation results concurrently affirmed positive influences of organic-inorganic N@P nanofillers on discharge energy density (Ud) and efficiency (η) of P(VDF-HFP)-based (PVH-based) nanocomposites. Remarkably, 1.3 vol% N@P/PVH achieves a high Ud of 21.7 J/cm3 and η of 81.2 % under 569.0 MV/m. More importantly, it maintains an excellent energy storage performance throughout 104 cyclic tests. This study presents a valid strategy for concurrently improving Ud and η of polymer-based nanocomposites.

Charge transfer reaction at gas-liquid interface of aqueous tetrabutylammonium iodide solution: influence of ions on dynamical response of solvent

Abstract Tetrabutylammonium iodide (TBAI) is known to create an electric double layer at the air-water interface. In the present study, we investigated the charge-transfer-to-solvent reaction from iodide ions to liquid water near the gas-liquid interface of an aqueous TBAI solution using extreme UV (EUV) time-resolved photoelectron spectroscopy. Use of EUV radiation ensured accurate measurements of electron kinetic energy distributions by minimizing spectral distortions caused by electron inelastic scattering in the liquid and the influence of the electron transmission efficiency through the gas-liquid interface. The spectra observed for photodetached electrons exhibited a rapid energy shift and a variation of the bandwidth in subpicoseconds, and the rates of these changes clearly depended on the TBAI concentration. The results indicate that the dynamical response of solvent water changes in the presence of a high density of ions.

HORTENSIA, a program package for the simulation of nonadiabatic autoionization dynamics in molecules.

We present a program package for the simulation of ultrafast vibration-induced autoionization dynamics in molecular anions in the manifold of the adiabatic anionic states and the discretized ionization continuum. This program, called HORTENSIA (Hopping Real-time Trajectories for Electron-ejection by Nonadiabatic Self-Ionization in Anions), is based on the nonadiabatic surface-hopping methodology, wherein nuclei are propagated as an ensemble along classical trajectories in the quantum-mechanical potential created by the electronic density of the molecular system. The electronic Schrödinger equation is numerically integrated along the trajectory, providing the time evolution of electronic state coefficients, from which switching probabilities into discrete electronic states are determined. In the case of a discretized continuum state, this hopping event is interpreted as the ejection on an electron. The derived diabatic and nonadiabatic couplings in the time-dependent electronic Schrödinger equation are calculated from anionic and neutral wavefunctions obtained from quantum-chemical calculations with commercially available program packages interfaced with our program. Based on this methodology, we demonstrate the simulation of autoionization electron kinetic energy spectra that are both time- and angle-resolved. In addition, the program yields data that can be interpreted easily with respect to geometric characteristics, such as bonding distances and angles, which facilitate the detection of molecular configurations important for the autoionization process. Furthermore, several useful extensions are included, namely, tools for the generation of initial conditions and input files as well as for the evaluation of output files, all of this both through console commands and a graphical user interface.