Characteristic Energy Loss Research Articles

Velocity Map Imaging Photoelectron Spectroscopy of Silver Iodide Aerosol Particles.

The valence band electronic structure of isolated silver iodide nanoparticles (AgI NP) was investigated by vacuum-ultraviolet aerosol photoelectron spectroscopy using the velocity map imaging technique (VUV VMI-PES). The VUV VMI-PES results were obtained for polydisperse aerosol produced by aggregation of hydrocolloid of silver iodide particles 8-15 nm in size. The ionization energy of the AgI particles was found to be 6.0±0.1 eV with respect to the vacuum level. The DFT calculations showed that the main contribution to the density of AgI electronic states in the valence region originates from I 5p orbitals. The dependence of the asymmetry parameter on the electron energy showed that the value of the characteristic energy loss of excited photoelectrons was 2.7 eV, which coincided with the band gap of the nanomaterial.

Analysis of the Fabrication and Applications for State-of-Art MOSFET and JFET

Semiconductor devices have always played a vital role in the field of electronics, and their development has promoted the rapid progress of modern electronic technology. Among them, MOSFET and JFET are two important semiconductor devices, and their wide application in the electronic field leads technological innovation in different fields. This study will introduce the fabrication and application of these two mainstream FET devices, while analyzing their future limitations and prospects. Some improvements in structure and material of both devices will be introduced. The performance enhancements including I-V characteristic curve and energy loss are shown in this article. Studying the development, types, and progress of MOSFET and JFET provides insights into their history and advancements, contributing to improved device performance and reliability. Applications in integrated circuits, quantum computing, solar cells, biomedicine, and communication highlight their wide-ranging impact. To sum up, understanding FETs limitations and future prospects drives further innovation, advancing technology and electronic systems.

Comparative Investigation of XPS Spectra of Oxidated Carbon Nanotubes and Graphene

X-ray photoelectron emission spectra of thermally reduced graphene oxide samples and carbon nanotubes (CNTs) with various oxidation degrees are presented in this paper. A method for the reconstruction of differential electron inelastic scattering cross sections from the energy loss spectra of photoelectrons is described and discussed. The analysis of the part of the characteristic photoelectron energy loss spectrum adjacent to the C1 peak indicated a considerable influence of the thermal reduction of graphene oxide on the electron properties of the samples obtained. On the contrary, the oxidation of CNTs by refluxing in a concentrated HNO3 solution does not change the free electron excitation spectrum.

Direct Visualization of Homogeneous Chemical Distribution in Functional Polyradical Microspheres.

It is demonstrated that the postfunctionalization of solid polymeric microspheres can generate fully and throughout functionalized materials, contrary to the expectation that core-shell structures are generated. The full functionalization is illustrated on the example of photochemically generated microspheres, which are subsequently transformed into polyradical systems. Given the all-organic nature of the functionalized microspheres, characterization methods with high analytical sensitivity and spatial resolution are pioneered by directly visualizing the inner chemical distribution of the postfunctionalized microspheres based on characteristic electron energy loss signals in transmission electron microscopy (TEM). Specifically, ultrasonic ultramicrotomy is combined successfully with electron energy loss spectroscopy (EELS) and electron spectroscopicimaging (ESI) during TEM. These findings open a key avenue for analyzing all-organic low-contrast soft-matter material structures, while the specifically investigated system concomitantly holds promise as an all-radical solid-state functional material.

Resonant inelastic x-ray scattering of spin-charge excitations in a Kondo system

Resonant inelastic x-ray scattering (RIXS) studies across the Ce ${M}_{5}$ edge have been carried out to investigate the electronic structure of the ferromagnetic ${\mathrm{CeAgSb}}_{2}$ Kondo system. The RIXS spectra exhibit energy loss features corresponding to final states usually observed by combining photoemission and inverse photoemission spectroscopy. At low energy loss, a clear signature of the spectral features corresponding to the spin-orbit interaction is also observed. Polarization dependence provides evidence for the ${}^{1}{S}_{0}$ symmetry singlet ground state by a total suppression of the ${f}^{0}$ final state. A simplified single-impurity Anderson model combined with full multiplet theory allows an accurate description of the spin-charge excitations. The RIXS data also reveal a strong temperature $T$ dependence of the fluorescencelike structure. We conjecture that this behavior reflects the $T$ dependence of the Kondo resonance.

Numerical modeling of energy dissipation of internal solitary waves encountering step topography

In this study, we conducted simulation experiments using a large-eddy simulation method to examine the interaction of internal solitary waves (ISWs) with step topography. We investigated the propagation, transmission, reflection, and breaking of depression ISWs. The features of ISW depend on the geometrical parameters of the step topography that define the initial setting. The relationships between the ISWs geometric and energy loss features as well as the initial setting parameters were analyzed; related empirical relations were developed. Following the analysis of the vortex changes during the process of wave-topography interaction, the different breaking processes and their development rules were discussed. The results showed that, as the obstacle height increased, the degree of energy conversion during the interaction increased. There is no explicit relationship between the loss of energy and energy conversion during the interaction of an ISW with an obstacle. The maximum wave energy loss obtained by eliminating the effect of the tailed wave generated during wave generation and considering the energy conversion is approximately 5%–10% lower than that obtained with traditional methods. Additionally, the mode-2 ISW was detected during the wave-topography interaction, and its velocity profiles in the vertical direction were analyzed, which may be one of the reasons for the accelerated energy dissipation in the system.

Identification of uranium hexavalent compounds using X-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy (XPS) has applications in many fields ranging from development of thin films for semi-conductors to post failure analysis of organic coatings and structural adhesives. The current work expands on that versatility by applying XPS to the growing field of nuclear forensics. This was achieved by the synthesis and characterisation of several uranium compounds, predominantly in the hexavalent state associated with the nuclear fuel cycle, and by X-ray diffraction and Raman spectroscopy analysis prior to XPS. Spectral characteristics for each compound are discussed, and interpretations made through observations in the binding energy of the U4f region as well as secondary energy loss features such as shake up satellites. The interpretation of such features is related to the stoichiometry, oxidation state and bonding structure of a range of uranium compounds. As XPS is typically insensitive to structural (crystallographic) variations, a rationale is provided for the relationship between structural variations, as measured by Raman and X-ray diffraction and compared to the open literature, and the XPS satellite to parent peak intensity of uranium compounds, providing a novel and useful approach for uranium compound characterisation. In addition to the novel approach described, Wagner chemical state plots have also been generated to provide another comparison tool.

Interface Carriers and Enhanced Electron‐Phonon Coupling Effect in Al2O3/TiO2 Heterostructure Revealed by Resonant Inelastic Soft X‐Ray Scattering

AbstractThe electronic structure and the electron‐phonon couplings in a novel mass‐production‐compatible Al2O3/TiO2 2D electron system (2DES) are investigated using resonant inelastic soft X‐ray scattering. The experimental data from the samples of various TiO2 thicknesses unequivocally show that the Ti3+ state indeed exists at the deep interface to serve as an n‐type dopant for the 2DES. The electronic structure of Ti3+ species is scrutinized as entirely separated from that of the Ti4+ host lattice. Furthermore, features of sub‐eV energy loss phonon modes are clearly observed, indicating substantial electron‐phonon coupling effects. Such low energy loss features are enhanced in thinner TiO2 samples, implying that polaronic local lattice deformation is enhanced due to the presence of Ti3+. These findings suggest that the 2DES properties can be controlled via well‐established TiO2 engineering, thereby enthroning the binary oxide heterostructure as a promising candidate for 2DES device applications.

Оптические свойства и электронные характеристики празеодима и неодима в конденсированном состоянии

The optical properties of unoxidized surfaces of polycrystalline Pr and Nd films in the spectral range 0.4 - 2.6 μm are studied. Optical constants were measured by Beattie ellipsometric method. Dispersion dependences of the optical conductivity σ, the reflectivity R, imaginary and real parts of the dielectric constant ε1 and ε2, and the function of characteristic electron energy losses Im (ε) -1 were calculated using the obtained optical constants. The paper presents the optical properties of both films and liquid metals studied earlier. The electronic characteristics of praseodymium and neodymium in solid thin-film and liquid states are calculated using the results of measurements in the infrared region of the spectrum using the two-band conductivity model.

ФОРМИРОВАНИЕ ТОНКИХ ПЛЕНОК MG2SI НА SI (111) И ИССЛЕДОВАНИЕ ИХ МЕТОДОМ ЭОС И СХПЭЭ

The paper presents information on the results of the formation of a thin Mg2Si film on a silicon substrate by solid-phase epitaxy in an ultrahigh-vacuum chamber of the PHI model 590 device. There are a number of difficulties in the formation of magnesium silicide films due to the low condensation coefficient and high vapor pressure. Effective methods for the formation of Mg2Si are currently being sought. As a result of our experiment, a thin film was obtained, which was studied in-situ by the method of electron Auger spectroscopy and spectroscopy of characteristic energy losses by electrons. Analysis of the Auger electron spectrum showed the presence of magnesium and silicon atoms in the composition of the formed film. From the analysis of the EELS spectra, it was found that a thin film of silicide magnesium was formed.

Thermodynamics Investigation and Spike-stall Identification Based on Energy Loss of Centrifugal Compressor

Although quantities of investigations concerning the stall characteristics and thermal-dynamics of centrifugal compressor were carried out, rare discussions, however, were employed on the relationship between energy loss and flow unsteadiness, especially the losses originating from spike-type stall in the impeller. In the present work, a combined unsteady numerical and experimental analysis of energy loss features under stall condition in the impeller of centrifugal compressor was presented. Firstly, an energy loss prediction model based on one-dimensional equations considering multiple components was proposed and validated against experimental data. The dominating loss mechanisms in the impeller were quantitatively evaluated and the corresponding effect of each loss on various operating conditions was measured by proposing a weight coefficient. In order to prove the possibility of the potential application of the present approach, the weight coefficient method was also employed in another centrifugal compressor and the results were well validated. Then the incidence loss, which has the leading three weight coefficients during the occurrence of stall, were investigated with the distribution of inflow angle and entropy near stall condition. Then, applying blade loading variations and vortex transport analysis allowed the relevance of blade loading loss and clearance loss to be taken into account. Finally, with the synergy angles introduced, the criteria of spike stall through losses identification and qualification were established. The results imply that friction loss, clearance loss and incidence loss account for the major part of the total losses with the weight coefficient of 48%, 29% and 19% near stall condition. However, the weight coefficient of incidence loss increases remarkably with those of other losses decreasing from design condition to stall condition, indicating the significant contribution of incidence loss to the occurrence of stall. Correspondingly, the dramatic increase of inflow angle at limited circumferential region can be treated as a general criterion for spike-stall. The influence of tip clearance leakage on the leading edge of splitter blade results in the decrease of blade loading at reduced mass flow. Based on the synergy angle distribution, mutation region of field synergy angle accompanied with the increase of flow resistance at the impeller inlet may lead to a more efficient determination of the spike-stall for compressor impeller.

The Electronic and Optical Properties of Thin Nanocluster Mo Films for Single-Photon UV Detectors

Results of a study of the electronic structure and optical properties of a novel material based on thin films comprised of Mo nanoclusters obtained by gas-phase magnetron sputtering are presented. The chemical composition of the obtained films immediately after deposition (in situ) and upon exposure to the atmosphere (ex situ) was investigated by X-ray photoelectron spectroscopy. It is shown that exposure to the atmosphere leads to “core–shell” oxidation of the nanoclusters the obtained films are composed of and changes in the valence band. The change in the electronic structure of the obtained films was investigated by spectro-scopy of the characteristic energy losses of electrons. The optical properties of the obtained films were investigated in the wavelength range of 185–800 nm. The possibility of creating thin-film photodetectors based on the obtained Mo nanocluster films for detecting isomeric nuclear transition decay in 229Th nuclei is discussed.

Numerical investigation and loss estimation of high-pressure turbine cascade flow with contoured endwall and incoming wakes

With the aim of suppressing the irreversible losses, the secondary flow at endwall and incoming vortices interactions are assumed to be the most concerned physics in gas turbine for modern aero-engine and military vehicles. However, the combining effect of contoured endwall and incoming periodic wakes were seldom discussed previously. In the present work, the research subject is the high-pressure turbine cascade with non-axisymmetric endwall and incoming wakes induced by moving bar fulfilled with periodic boundary conditions in pitchwise direction. Firstly, the aerodynamics and thermodynamics in the turbine cascade with secondary flow control technique, which denotes to non-axisymmetric endwall, were experimentally and numerically investigated. For what concerns the profile aerodynamic loadings, total pressure loss coefficients and vortices coefficient were surveyed to quantify the influence of interaction between incoming wakes and secondary flow at contoured endwall. The cumulative difference of entropy production rate associated with dissipation is then employed to evaluate the loss under different inflow condition. Combined with dynamic mode decomposition (DMD) method, the energy loss features associated with incoming wakes at different passing frequencies was captured. The results indicated that the flow separation at the suction wall with the axial position of 70%∼80% Cax upstream trailing edge was suppressed in the cases with incoming wakes for high pressure turbine cascade. And stronger incoming wakes tends show better suppression effect on the flow separation. However, when combined with contoured endwall, the negative influence of non-axisymmetric endwall at the middle passage was enlarged. And the general aerodynamics of the cascade flow may not be necessarily improved in term of energy loss characteristics with the increase of passing frequency of incoming wakes. The present work preserves guiding significance for the design and flow control of high pressure turbine cascade.

Mathematical model of the technological vibratory unit with electromagnetic excitation

The mathematical model of the technological vibratory unit with electromagnetic excitation is considered to its features that are important for the dynamic design problems. The model is based on the differential equations of electrical balance and mechanical balance, taking into account the mobility degree of inertial masses with spring linkages. The vibratory unit vibration properties are analyzed concerning the power voltage and frequency coupling, interacting inertia masses mobility degree, spring linkages properties, magnetic core steel magnetizing characteristic non-linearity, leakage fluxes, electric, magnetic and mechanical energy losses. The research performed for dynamical design problem solution is distinguished by a novel approach to the estimation of the capability of changing vibration properties of the movable operating element of the technological vibratory unit with an additional mass attached to it. The model design technology based on the structural modelling method supported by Matlab Simulink is proposed. The research results can be useful for specialists in vibration engineering, machines and devices durability dynamics and vibroprotection.

Production of Ablated CeO2 Particles with Nanodispersed Compositional Distribution

A technique for obtaining ablated CeO2 particles of nanodispersed composition has been developed. With the help of transmission electron microscopy and small-angle X-ray scattering diffractometry, it was found that the limiting particle size in a colloidal solution does not exceed 30 nm. It was established by spectroscopy of characteristic electron energy losses that the content of defects in oxygen vacancies increases with decreasing sizes of ablated nanoparticles.

Determination of the Optical Properties and Electrical Characteristics of Solid and Liquid Ytterbium with Ellipsometric Measurements

An ellipsometric method is used to study the optical properties of unoxidized surfaces of polycrystalline ytterbium film in the spectral range of 0.4–2.6 mm. The measured refractive indices and absorption coeffi cient of the film are used to calculate the dispersion dependences of the optical conductivity σ reflectivity R, the imaginary and real parts of the dielectric constant e1 and e2, and the characteristic electron energy loss functions Im(e–1). The infrared measurements are used in a two-band model for the conductivity to calculate the electronic characteristics of ytterbium in the solid and liquid states.

Annealing Effect on the Composition and Electrophysical Properties of N-Type Silicon Surface

During low-temperature annealing, the segregation of the alloying element leads to a strong enrichment of the surface layer, causing a rearrangement of the surface electron structure. This change in the electron structure is manifested in the characteristic energy loss spectra. Annealing of single crystals at 400–500 K leads to an increase in the density of surface electron states. As shown by the calculations of the surface potential using experimental data on the temperature dependence of the surface concentration, dopant segregation causes a linear increase in the surface potential.

Characteristic energy loss of electrons in Mg with angle resolution

The article discusses electron energy loss of bulk and surface plasmons in solid polycrystalline Mg films. The experimental study of the electrons’ characteristic energy loss is conducted and its results are compared in a wide range of electron incidence angles on the sample (0°–89°), dispersion angles (5°–165°) and electron energies (100–600 eV). Electron wave refraction at the vacuum–solid state interface is considered as one of the factors determining the intensity of surface plasmons.

Photophysics, morphology and device performances correlation on non-fullerene acceptor based binary and ternary solar cells

Abstract Non-fullerene acceptor (NFA) based organic solar cells (OSCs) are of high efficiency and low energy loss and low recombination features, which is owing to the advantage of non-fullerene acceptors. The photophysics investigation of non-fullerene solar cells, in comparing to fullerene based analogue as well as mixed acceptor ternary blends could help to understand the working mechanism of NFA functioning mechanism. We choose PBDB-T donor, the fullerene derivative PC71BM acceptor, and the non-fullerene acceptor ITIC as the model system, to construct binary and ternary solar cells, which then subject to ultrafast spectroscopy investigation. The charge transfer pathway in binary and ternary blends is revealed. And it is seen that ITIC leads to a faster exciton separation and exciton diffusion. ITIC in blends suppresses the geminate recombination and shows smaller amount of charge transfer states, which is beneficial for the device performance. And the addition of ITIC enhances the crystallinity for both donor and acceptor leads to a morphology change of forming bicontinuous crystalline networks and phase separation. In a consequence, fill factor and JSC, increase dramatically for the related OSC.

Effect of Spatial Dispersion on Plasmon Resonance in Silver Nanoparticles

Using the modified discrete sources method, the problem of calculating plasmon spectra of the characteristic energy loss of electrons during the interaction with silver nanoparticles from 2 to 8 nm in size is solved. The calculated spectra are compared with the experimental data confirming the significant spatial dispersion effect. The importance of the consideration of this factor when analyzing the properties of plasmonic nanoparticles for applications in biosensorics and biomedicine is discussed.