Oscillator Energy Research Articles

Translational eigenstates of He@C60 from four-dimensional abinitio potential energy surfaces interpolated using Gaussian process regression.

We investigate the endofullerene system 3He@C60 with a four-dimensional potential energy surface (PES) to include the three He translational degrees of freedom and C60 cage radius. We compare second order Møller-Plesset perturbation theory (MP2), spin component scaled-MP2, scaled opposite spin-MP2, random phase approximation (RPA)@Perdew, Burke, and Ernzerhof (PBE), and corrected Hartree-Fock-RPA to calibrate and gain confidence in the choice of electronic structure method. Due to the high cost of these calculations, the PES is interpolated using Gaussian Process Regression (GPR), owing to its effectiveness with sparse training data. The PES is split into a two-dimensional radial surface, to which corrections are applied to achieve an overall four-dimensional surface. The nuclear Hamiltonian is diagonalized to generate the in-cage translational/vibrational eigenstates. The degeneracy of the three-dimensional harmonic oscillator energies with principal quantum number n is lifted due to the anharmonicity in the radial potential. The (2l + 1)-fold degeneracy of the angular momentum states is also weakly lifted, due to the angular dependence in the potential. We calculate the fundamental frequency to range between 96 and 110 cm-1 depending on the electronic structure method used. Error bars of the eigenstate energies were calculated from the GPR and are on the order of ∼±1.5 cm-1. Wavefunctions are also compared by considering their overlap and Hellinger distance to the one-dimensional empirical potential. As with the energies, the two abinitio methods MP2 and RPA@PBE show the best agreement. While MP2 has better agreement than RPA@PBE, due to its higher computational efficiency and comparable performance, we recommend RPA as an alternative electronic structure method of choice to MP2 for these systems.

Activation energy of heterogeneous catalytic oxidation of methanol in oscillatory regime

A new equation for the determination of activation energy of chemical oscillations was obtained in the reaction of methanol oxidation on a Pd catalyst. The maximum temperature, TM, of oscillations depends on the arrangement of the same quantity of the catalyst in the reactor, with the other experimental conditions kept constant.

Investigation of optical and dispersion parameters poly vinyl alcohol doped Safranin O dye (PVA/SO) thin film

Optical characteristics of polyvinyl alcohol/Safranin O dye (PVA/SO) thin films prepared by casting technique have been examined. Compositions and crystalline features of PVA/SO thin films are investigated with X-Ray Diffraction analyses. Ultraviolet–Visible spectroscopy has been utilized to measure the absorption and transmission optical properties of the thin films through the wavelength range 300-900 nm. Two regions can be recognized in absorption coefficient related to the direct band gaps, which are about 3.93 eV of the fundamental energy gap and 2.11eV of the onset gap. The theoretical WempleDiDomenico model has been performed to quantify the static refractive index n and the dispersion energy in addition to the oscillation energy (Eo). The results reveal that the data of the refractive index dispersion in this model obeyed the single oscillator, which is used to deduce the dispersion and the high frequency dielectric constant. In the examined wavelength range, it has been investigated the complex dielectric constant of PVA/SO dye thin films. The ratio of the carrier concentration to the effective mass has been estimated. Oscillation energy values have been examined in this study by describing the expression Eo ≈ Eg and checking the Wemple-DiDomenico model. PVA/SO thin films have interesting physical properties for solar cell applications.

The violet laser irradiation influence on the dispersive properties of the PVA/MO composite thick

Polyvinyl alcohol (PVA) polymer, methyl orange (MO) and their composite was dissolved in water in order to prepare films with different thickness by casting method. The films were irradiated by a violet laser with a wavelength 405 nm for different times (0, 10, 20, 30 and 40) minute. The dispersion parameters were calculated before and after exposure to the laser using the Wemple–DiDomenico method. Dispersion energy (E d) and the single oscillator energy of electronic transition (E o) were increased with increasing the irradiating time for PVA, MO and PVA/MO thick films. This is useful to modify geometrical and optical specifications for materials which has many applications especially in the medical field. The Urbach energy also can be controlled by the irradiation times since it decreased with increasing the laser irradiation time which can be used to enhance the structure of the material.

Influence of ion beam on the surface characteristics and structural properties of PVA/TiO2 films

This work used the solution-casting preparation method to create flexible polymer composite materials including titanium dioxide (TiO2) and poly(vinyl alcohol) (PVA). Then, using a wide-beam homemade cold-cathode ion generator, the samples were irradiated with oxygen fluences of 4 × 1016, 8 × 1016 and 12 × 1016 ions/cm2. Using the energy-dispersive X-ray spectroscopy, contact angle and X-ray diffraction techniques, the successful production of PVA/titanium dioxide composite films was evaluated. The effects of ion exposure on the optical behavior were determined using the ultraviolet–visible spectroscopy technique. The PVA/titanium dioxide dispersion energy was 1.75 eV. It increased to 2.21, 2.66 and 3.12 eV with irradiation of 4 × 1016, 8 × 1016 and 12 × 1016 ions/cm2, respectively. Moreover, the refractive index (n 0) of PVA/titanium dioxide was 1.18, which increased to 1.25, 1.32 and 1.40, respectively. Moreover, the oscillation energy E 0 reduced from 4.24 eV for the PVA/titanium dioxide composite to 3.84, 3.64 and 3.27 eV, respectively. Consequently, PVA/TiO2 films are treated with ions to change their optical and structural properties, which are then used in a variety of optoelectronic applications.

Optical and optoelectronic properties of gallium oxide films fabricated by the chemical vapour deposition method

The present work investigated the influence of growth time on the structural, optical, and optoelectronic properties of β-Ga2O3 films produced on Si substrates by the chemical vapour deposition method. The prepared films were characterized by X-ray diffraction, field-emission scanning electron microscope, and UV–Vis spectrophotometer. The films exhibited a mixed phase (β-α)-Ga2O3 crystal structure. The crystallite size ranged between 34.98 and 164.69 nm. The bandgap increased from 4.74 to 4.88 eV. The absorption and extinction coefficients were in the orders of 103 and 10−1, respectively. The refractive index, dispersive energy and single oscillator energy increased from 1.86 to 1.87, 19.24 to 28.64, and 8.36 to 9.54, respectively, with an increase of growth time. The oscillator strength, oscillator wavelength, third-order nonlinear optical susceptibility and dispersion of refractive index were in the orders of 10−4, 10−2, 10−10 and 10−9, respectively. The carrier concentration, optical conductivity, optical mobility, and optical resistivity were also evaluated. The real and imaginary dielectric constants, and plasmon frequency were also determined.

Interactions and ultrafast dynamics of exciton complexes in a monolayer semiconductor with electron gas

Abstract We present femtosecond pump-probe measurements of neutral and charged exciton optical response in monolayer MoSe2 to resonant photoexcitation of a given exciton state in the presence of 2D electron gas. We show that creation of charged exciton (X−) population in a given K+, K− valley requires the capture of available free carriers in the opposite valley and reduces the interaction of neutral exciton (X) with the electron Fermi sea. We also observe spectral broadening of the X transition line with the increasing X− population caused by efficient scattering and excitation induced dephasing. From the valley-resolved analysis of the observed effects we are able to extract the spin-valley relaxation times of free carriers as a function of carrier density. Moreover, we analyze the oscillator strength and energy shift of X in the regime of interaction with electron Fermi sea under resonant excitation. From this we can observe the process of X decay by radiative recombination paired with trion formation. We demonstrate an increase of neutral exciton relaxation rate with the introduction of Fermi sea of electrons. We ascribe the observed effect to the increased efficiency of the trion formation, as well as the radiative decay caused by the screening of disorder by the free carriers.

A novel memristive neuron model and its energy characteristics.

The functional neurons are basic building blocks of the nervous system and are responsible for transmitting information between different parts of the body. However, it is less known about the interaction between the neuron and the field. In this work, we propose a novel functional neuron by introducing a flux-controlled memristor into the FitzHugh-Nagumo neuron model, and the field effect is estimated by the memristor. We investigate the dynamics and energy characteristics of the neuron, and the stochastic resonance is also considered by applying the additive Gaussian noise. The intrinsic energy of the neuron is enlarged after introducing the memristor. Moreover, the energy of the periodic oscillation is larger than that of the adjacent chaotic oscillation with the changing of memristor-related parameters, and same results is obtained by varying stimuli-related parameters. In addition, the energy is proved to be another effective method to estimate stochastic resonance and inverse stochastic resonance. Furthermore, the analog implementation is achieved for the physical realization of the neuron. These results shed lights on the understanding of the firing mechanism for neurons detecting electromagnetic field.

Electrochemical measurement of the electronic structure of graphene via quantum mechanical rate spectroscopy

Quantum-rate theory defines a quantum mechanical rate ν that complies with the Planck–Einstein relationship E=hν, where ν=e2/hCq is a frequency associated with the quantum capacitance Cq, and E=e2/Cq is the energy associated with ν. Previously, this definition of ν was successfully employed to define a quantum mechanical meaning for the electron-transfer (ET) rate constant of redox reactions, wherein faradaic electric currents involved with ET reactions were demonstrated to be governed by relativistic quantum electrodynamics at room temperature (Bueno, 2023c).This study demonstrated that the definition of ν entails the relativistic quantum electrodynamics phenomena intrinsically related to the perturbation of the density-of-states dn/dE=Cq/e2 by an external harmonic oscillatory potential energy variation. On this basis, the electronic structure of graphene embedded in an electrolyte environment was computed. The electronic structure measured using quantum-rate spectroscopy (QRS) is in good agreement with that measured through angle-resolved photo-emission spectroscopy (ARPES) or calculated via computational density-functional theory (DFT) methods.Electrochemical QRS has evident experimental advantages over ARPES. For instance, QRS enables obtaining the electronic structure of graphene at room temperature and in an electrolyte environment, whereas ARPES requires low temperature and ultrahigh-vacuum conditions. Furthermore, QRS can operate in-situ using a hand-held, inexpensive piece of equipment, whereas ARPES necessarily requires expensive and cumbersome apparatus.

Influence of the content of stacked ZnO on the structural and optical properties of heterostructured ZnO/Ga2O3 films

The rising demand for heterojunction materials stimulated by the great achievements of modern nanotechnology has triggered enormous interests in the investigation of their materials properties. Heterostructured ZnO/Ga2O3 has been deployed for different device applications, but its several optical parameters have rarely been investigated. The present work attempts to investigate the influence of the thickness of stacked ZnO layer on the surface of Ga2O3 film. Optical parameters, such as absorption and extinction coefficient, Urbach energy, refractive index, dielectric constants, optical dispersion energy, single oscillator energy, static refractive index, oscillator strength, and oscillator wavelength of the ZnO/Ga2O3 films were studied. Morphological characterization showed microstructures of various shapes. Cross-section measurements showed that the thickness of the Ga2O3 layer remained approximately the same for all samples, while the thickness of the ZnO layer increased from 0 to 5.14 nm. Structural analysis revealed the coexistence of β-Ga2O3 and wurtzite ZnO crystal phases. UV–Vis absorption spectra demonstrated two distinct absorptions belonging to the β-Ga2O3 and ZnO. The bandgap of the composite ranged between 4.43 and 4.69 eV with an increase in the amount of ZnO at the surface. The absorption and extinction coefficient were in the order of 103 cm−1 and 10−5, respectively. The Urbach energy ranged between 0.688 and 1.125 eV. The refractive index was in the range 2.09–2.85, while the static refractive index ranged between 1.90 and 2.73. Also reported were other optical parameters, such as the real and imaginary dielectric constant, dispersive energy, single oscillator energy, oscillator strength, and oscillator wavelength.

Tailoring the linear and nonlinear optical properties of PVC/PE blend polymer by insertion the spindle copper nanoparticles

PVC/PE polymer nanocomposites were synthesized with 0–3 wt% copper (Cu) nanoparticles via melt extrusion. XRD analysis showed characteristic peaks corresponding to crystalline PVC, PE, and Cu phases. FTIR confirmed the presence of signature vibrational modes of PVC and PE. Optical studies revealed tunable light absorption, refractive index, dielectric response, and bandgap by tailoring copper content. The composites displayed enhanced linear and nonlinear optical susceptibilities, with potential applications in photonics. Optical absorption studies revealed a redshift in bandgap from 3.38 eV to 2.19 eV as Cu concentration increased from 0 to 3%, indicating enhanced visible light absorption. The real dielectric constant rose from 1.3527 to 1.4578 at 190 nm wavelength when Cu content was raised from 0 to 3%. Imaginary dielectric constant exhibited a stepwise enhancement from 2.43 × 10−3 to 3.97 × 10−3 at 190 nm with increasing Cu loading up to 3 %. The nonlinear refractive index varied from 1.2 × 10−8 cm2/W to 2.1 × 10−8 cm2/W across 500–900 nm wavelengths for 0–3% Cu. Meanwhile, the dispersion parameters including, the single oscillator energy (Eo) and the dispersion energy (Ed) were extracted. The relaxation time of the studied samples were extracted, which decreased after the insertion the nanofillers. The outcomes revealed that Cu nanoparticles' doped films favor a high-speed optoelectronic device more than the pristine film.The results demonstrate tunable optical and dielectric characteristics, underscoring the potential of Cu-based PVC/PE nanocomposites.

СВЧ-УСТАНОВКИ С КАМЕРАМИ ГИБРИДНОГО ТИПА ДЛЯ ОБРАБОТКИ СЕЛЬСКОХОЗЯЙСТВЕННЫХ КУЛЬТУР, ДИЭЛЕКТРИЧЕСКИХ И ПОЛИМЕРНЫХ МАТЕРИАЛОВ

A classification of areas of agriculture in which the energy of microwave electromagnetic oscillations is used for processing materials is proposed. The possibility of forming a new field based on the use of microwave installations on hybrid-type working chambers has been shown, which will allow an agricultural producer to enter the commodity market not only with agricultural products, but also with polymer materials with new properties obtained through non-thermal microwave modification in the technological block of Microwave installations. A comparison has been made of studies on the use of microwave energy in technological processes in a market economy. The practical significance of the given analysis of the use of microwave energy in agriculture is indicated.

Modernization of an existing microwave installation for microwave processing of biological substrates

One of the urgent tasks for breeding and seed centers producing elite and superelite seeds is to reduce excess moisture, which leads to reduced storage, reduced efficiency of use, deterioration in the commercial quality of products after drying, and contributes to the rapid development of pathogenic pathogens that render grain unusable ( average losses of grain without drying are 15...18%). Existing methods of reducing seed moisture are the use of drying devices, the significant disadvantages of which are: high energy intensity, the use of diesel and gas fuels, which pollute the environment, and the high cost of installations, which increases the cost of the final product. It is proposed to develop an energy-saving technology to obtain agricultural products with improved qualities, expanding the functionality of the use of equipment both for seed production enterprises and agricultural enterprises, as well as for processing polycaproamide threads used as suture material in veterinary medicine. Ultrahigh-frequency electrotechnological installations, which use the energy of electromagnetic oscillations of ultrahigh frequency, can carry out thermal microwave modification of biological substrates and non-thermal microwave modification of polycaproamide threads. The paper presents an installation with a hybrid-type working chamber, in which thermal and non-thermal microwave modification of biological substrates and polycaproamide threads is simultaneously carried out. The presented installation is cheaper, it requires one rather than two microwave generators, and it occupies less space than two separate installations.

Fast spatial laser beam modulation for improved process control in Laser Powder Bed Fusion

We report on the implementation of a high frequency beam oscillation (wobbling) strategy for improving process control during laser powder bed fusion of single weld tracks on Inconel 625. Oscillation frequencies ranging from ~ 600 Hz to 7000 Hz, and different oscillation trajectories (circular, parallel or perpendicular to the direction of scanning) were explored. Highspeed imaging was used to elucidate the dynamics of the melt pool induced by the wobble beams, along with in situ absorptivity measurements to substantiate our hypothesis that the dynamic nature of wobble beams reduces absorptive losses due to laser-vapor interactions and results in improved coupling at the melt pool. Operando X-ray radiography was carried out to visualize sub-surface melt flow dynamics, correlate to spatter mechanisms and optimize the window for improving process stability. Our observations indicate that wobble beams increase the aspect ratio of the melt pool by up to 4×, depending on the oscillation frequency and energy input. Highspeed imaging and X-ray radiography reveal an optimized process parameter window for reducing spatter, improving absorptivity and creating a stable melt pool at high (several kHz) oscillation frequencies.

2D capsid formation within an oscillatory energy landscape: orderly self-assembly depends on the interplay between a dynamic potential and intrinsic relaxation times.

Multiple dissipative self-assembly protocols designed to create novel structures or to reduce kinetic traps have recently emerged. Specifically, temporal oscillations of particle interactions have been shown effective at both aims, but investigations thus far have focused on systems of simple colloids or their binary mixtures. In this work, we expand our understanding of the effect of temporally oscillating interactions to a two-dimensional coarse-grained viral capsid-like model that undergoes a self-limited assembly. This model includes multiple intrinsic relaxation times due to the internal structure of the capsid subunits and, under certain interaction regimes, proceeds via a two-step nucleation mechanism. We find that oscillations much faster than the local intrinsic relaxation times can be described via a time averaged inter-particle potential across a wide range of interaction strengths, while oscillations much slower than these relaxation times result in structures that adapt to the attraction strength of the current half-cycle. Interestingly, oscillation periods similar to these relaxation times shift the interaction window over which orderly assembly occurs by enabling error correction during the half-cycles with weaker attractions. Our results provide fundamental insights to non-equilibrium self-assembly on temporally variant energy landscapes.

Oscillation Energy Transfer and Integrated Stability Control of Grid-forming Wind Turbines

Oscillation Energy Transfer and Integrated Stability Control of Grid-forming Wind Turbines

FEATURES OF VIBRATION DAMPERS APPLICATION IN THE DESIGN OF VIBRATION-RESISTANT METAL CUTTING TOOLS

Dry and viscous friction is used as a damper of oscillation energy in the construction of metal-cutting tools. A mathematical model of a two-mass oscillatory scheme of the insert of an assembled milling cutter was developed and studied, one of the masses of which models the clamped part of the insert - a press connection with dry friction, and the other - the cantilever part, which is subject to self-oscillations that are possible in the process of metal cutting. The influence of dry friction in the press joint of the insert on the amplitude of resonant oscillations of the cutter and the part was analyzed. The possibility of reducing the magnitude of the cutter's self-oscillations is demonstrated by selecting the most suitable parameters for the press connection of inserts with the body of the assembled milling cutter. The influence of internal viscous friction in materials with a high level of energy damping on the amplitude of self-oscillations of the cutter was evaluated and the possibility of their use in the design of a vibration-resistant metal-cutting tool was considered.

The spectral properties and dispersion parameters of electrospun nanofibers Poly(vinyl alcohol/ Poly(acrylamide)

Electrospun nanofibers based on polyvinyl alcohol (PVA), polyacrylamide (PAAm), and a PVA-PAAm blend (50/50 wt.%) were effectively made a room temperature(RT) and a voltage of (12kV). The products were studied using Field Emission Scanning Electron Microscope (FESEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy(FT-IR) and Ultraviolet-visible (UV–Vis) spectroscopy. The result of FESEM analysis showed that the polymer PVA, PAAm, and blend samples produced a random distribution of fine fibres at an average diameter of (214.12, 317.1, 157.65) nm with a smooth surface. In addition, the FESEM images demonstrate the fibres' suitability for use in gas sensing applications due to their branching fibres and porosity surface. XRD showed that the film polymeric of PVA, PAAm polymeric blend PVA-PAAm was seen to have a semicrystalline nature. According to the FTIR analysis, the PVA and PAAm networks in the PVA-PAAm polymer nanofibers were entangled due to the powerful hydrogen bond contact between the PAAm and PVA chains. Observed around (3473.79 and 3414) cm-1 were attributed to the N–H vibration and overlapped to O–H stretching. The spectra of the prepared films exhibit prominent absorption peaks, which are at the wavelength range (200-320) nm. PVA-PAAm polymer nanofibers decrease the energy gap from 3.70eV to 3.40eV. The Wemple-DiDomenico model was used to derive dispersion parameters such as dispersion energy, single oscillator energy, Urbach energy, the static refractive index and the moments of optical spectra the result of calculating by this model was compatible with that value calculated by the Tauc relation. While increased which qualifies them to be used in the electronic devices.

Analytical evaluations of the path integral Monte Carlo thermodynamic and Hamiltonian energies for the harmonic oscillator.

By using the recently derived universal discrete imaginary-time propagator of the harmonic oscillator, both thermodynamic and Hamiltonian energies can be given analytically and evaluated numerically at each imaginary time step for any short-time propagator. This work shows that, using only currently known short-time propagators, the Hamiltonian energy can be optimized to the twelfth-order, converging to the ground state energy of the harmonic oscillator in as few as three beads. This study makes it absolutely clear that the widely used second-order primitive approximation propagator, when used in computing thermodynamic energy, converges extremely slowly with an increasing number of beads.

Optical studies on thermally evaporated Ge–Se/Ge-Sb-Se chalcogenide glass films by spectroscopic ellipsometry

The GexSb30-xSe70: x = 30, 25, 15, 10 glass films were prepared by thermal evaporation technique. The surface morphology of glass films was studied by atomic force microscopy. The samples exhibited surface roughness with a root mean square value falling within the 0.89–1.47 nm range. The optical properties were precisely characterized by spectroscopic ellipsometry in the 4.13–0.77 eV spectral range. The Cody-Lorentz dispersion model was used to fit the data across the entire spectral range and extract the optical functions of glass films. It has been observed that the refractive index, n values rise with increasing energy, reaching a peak, and then experience a subsequent decline. The refractive index values exhibit a rising trend with an increase in Sb content. The optical bandgap, Egopt was found to follow a decreasing pattern with a decrease in Ge content. The refractive index dispersion curve was analyzed using the Wemple and DiDomenico single oscillator model in the lower absorption spectral region. It has been observed the values of oscillator energy, Eo, and static refractive index, n0, exhibit a pattern consistent with that of Egopt , and n, respectively. The optical properties, such as the high-frequency dielectric constant, carrier concentration, plasma frequency, and optical conductivity were analyzed.