Atomic Energy Levels Research Articles

Electronic transitions between energy levels without the emission of electromagnetic radiation

In a previous paper, it was explained that the absorption and emission process (AE-process) of Bohr’s model of the hydrogen atom must involve an electric charge (i.e., electron) transiting between atomic energy levels instead of quantum jumping; otherwise, there is no way to use the AE-process to predict the fine structure constant. In this paper, it is shown that (1) a complete oscillation of the atomic electron (i.e., an electric charge) and of the induced magnetic field must occur for Bohr’s hydrogen atom to emit electromagnetic radiation, and (2) an atomic electron (i.e., electric charge) of Bohr’s hydrogen atom can transit between energy levels without the atom emitting electromagnetic radiation.

Systematic investigation of transitions to J-mixed Pr I – levels

In JQSRT 305 (2023) 108596 we have recently published the discovery of two energy levels of the Pr atom that exhibit strong J-mixing. Additionally, we present here the manifold of observed hyperfine (hf) structure patterns. Their appearance of these patterns is not solely determined by the J-values of the combining upper levels; the composition of their wave functions also plays a cruical role. In total, we identified 49 transitions involving the J-mixed levels, and laser-spectroscopic investigations were conducted for 46 of them. Notably, 13 upper energy levels are reported for the first time in this study. We hope that this investigation will serve as a catalyst for semi-empirical or ab-initio calculations aimed at explaining these observations.

Hardware, methodology and applications of 2+D backscatter Mössbauer spectroscopy with simultaneous x-ray and γ-ray detection

A unique method is presented for the acquisition and analysis of 57Fe backscatter Mössbauer spectra with simultaneous detection of the resonant 14.4 keV γ-rays and the characteristic 6.4 keV x-rays, using a custom-built multi-parameter analyser constructed on the basis of commercial analogue to digital converters and high-speed digital latches. The system allows for the simultaneous registration of Doppler-modulation velocities and photon energies, with up to 4096 and 8192 digital channels respectively. This arrangement is in contrast to most related systems, which detect at a single narrow energy window per detector. Samples of arbitrary atomic structure, morphology and surface topography can be studied without altering the setup or the analysis procedure, provided that the samples are at least micrometre sized. The hardware and software that are used to acquire data with minimal dead time are described and the custom and self-contained methods for post-measurement energy discrimination, background correction and velocity-axis folding are discussed. The data are fit using a general Hamiltonian model for the nuclear energy levels of 57Fe and a quantum mechanical description of the angular momentum coupling is utilised, with consideration of the crystalline and chemical disorder of the sample under examination. Three examples of distinct magnetic systems, with thicknesses ranging from m to 6 mm, that were studied using this method are presented, these are: an amorphous CoFeB-based ribbon with ultra-soft coercivity for high-frequency applications, magnetically hard Nd-Fe-B thick films on Si substrates, examined in both as-deposited and annealed states, and a sample from the nickel-rich iron meteorite NWA 6259 that contains the atomically ordered, elevated coercivity, phase of FeNi, tetrataenite. The wide applicability and usefulness of this method is thus demonstrated on three distinct sample morphologies that required little to no surface preparation prior to examination.

Activation of Al2O3 surface passivation of silicon: Separating bulk and surface effects

Understanding surface passivation arising from aluminium oxide (Al2O3) films is of significant relevance for silicon-based solar cells and devices that require negligible surface recombination. This study aims to understand the competing bulk and surface lifetime effects which occur during the activation of atomic layer deposited Al2O3. We demonstrate that maximum passivation is achieved on n- and p-type silicon with activation at ∼ 450 °C, irrespective of annealing ambient. Upon stripping the Al2O3 films and re-passivating the surface using a superacid-based technique, we find the bulk lifetime of float-zone and Czochralski silicon wafers degrade at annealing temperatures > 450 °C. By accounting for this bulk lifetime degradation, we demonstrate that the chemical passivation component associated with Al2O3 remains stable at activation temperatures of 450─500 °C, achieving an SRV of < 1 cm/s on n- and p-type silicon. In conjunction with the thermal stability, we show that films in the range of 3–30 nm maintain an SRV of < 1 cm/s when annealed at 450 °C. From atomic-level energy dispersive X-ray analysis, we demonstrate that, post deposition, the interface has a structure of Si/SiO2/Al2O3. After activation at > 300 °C, the interface becomes Si/SixAlyO2/Al2O3 due to diffusion of aluminium into the thin silicon oxide layer.

Spherically confined hydrogenic atoms under classical non‐ideal plasmas: Scaling law for the critical cage size

AbstractAn elegant calculation is carried out to investigate the effects of the non‐ideality of classical plasma on the energy levels of the hydrogenic atoms held in a spherical cage. Organized effect of the non‐ideal classical plasma is described by an analytical pseudopotential which contains the Debye length and non‐ideality parameter as parameters. Convergent results for the bound states are obtained variationally by utilizing a large trail function containing cosine term which automatically takes care of the requisite boundary conditions. For the plasma‐free case, our results are in excellent agreement with the most accurate results available in the literature. An inclusive study is made to explore the changes emerging in the energy levels due to the variation of the plasma parameters and cage size. Special emphasis is made on the determination of critical cage size precisely. The present study specifically reveals that the increasing plasma non‐ideality leads to the elongation of the critical cage size. Moreover, it is empirically found that the critical cage size for a given hydrogenic atom can be obtained from a scaling law.

Fluctuations of atomic energy levels due to axion dark matter

Fluctuations of atomic energy levels due to axion dark matter

Fitting for the energy levels of hydrogen

Atomic hydrogen energy levels calculated to high precision are required to assist experimental researchers working on spectroscopy in the pursuit of testing quantum electrodynamics (QEDs) and probing for physics beyond the Standard Model. There are two important parts to the problem of computing these levels: an accurate evaluation of contributions from QED and using an accurate value for the proton charge radius as an input. Recent progress on QED corrections to the fine structure, as well as increasing evidence that a proton charge radius in the range of 0.84 fm is favored over the previously adopted larger value in the 0.88 fm range, has advanced the field, yet several state-of-the-art measurements remain in contradiction with this smaller value. Motivated by on-going and future work in this area, we present here a simple parameterization for the energy levels of hydrogen at the level of hyperfine structure using the so-called relativistic Ritz approach. The fitting of a finite sample of QED-generated levels at low to intermediate principal quantum number, n, gives a generally applicable formula for all values of n for each distinct angular momentum channel, given in this work up to orbital angular momentum number . We also provide a simple linear parameterization for the shift in hydrogen energy levels as a function of the proton radius, providing a useful cross check for extant and future measured energy intervals.

Nuclear Energy Levels Scheme of 46Cr Using FPD6, FPY, and KB3G Interactions

The 46Cr isotope nuclear energy levels were studied using low-level FP-LS shell inside the shell model calculations. Nuclear energy levels have been calculated using FPD6, KB3G, and FPY interactions in the fp-shell model space and F742 and F7MBZ in the f7/2 model space. The results are compared to one another and to the experimental data that is already accessible and specific outcomes are clearly in agreement. In addition to having a strong arrangement in the reproduced values of the energy levels scheme, the used model space interactions are the two-body matrix element in the fp-shell model space that is best fitted. Particularly below 3 MeV, the general estimation of the replicated data is good. The wave vectors and analysis are modeled in diagrammatic notation, and all inscriptions are given in this style. Utilizing the oscillator's potential, a single particle vector is built, using 40Ca as the core of the fp-shell and f7/2 model space. Results are obtained for all tested nuclei using the OXFORD BUENOS AIRES SHELL (OXBASH) model code.

Experimental and Semiclassical Stark Widths and Shifts for Spectral Lines of Neutral and Ionized Atoms (A Critical Review of Experimental and Semiclassical Data for the Period 2008 Through 2020)

This Review Article compares new experimental and corresponding semiclassical Stark broadened data for non-hydrogenic spectral lines of neutral atoms and positive ions. This Review covers the period 2008 until the end of 2020 and presents the continuation of previous critical reviews from 1976 (two), 1984 (two), 1990, 2002, and one from 2009. This Review reports the Stark broadening parameters of 1665 spectral lines belonging to 35 elements with 61 different atomic and ion species. The data are taken from 60 papers. Experimental data are arranged by elements and spectra, and these are reported in tables in alphabetical and numerical order, respectively. Each experimental Stark broadening parameter is followed with estimated accuracy. The experimental Stark broadening and shift data presented in the tables are compared with the corresponding semiclassical results available in the literature. In addition, for comparison experiments versus semiclassical theoretical Stark broadening parameters, a numerically improved theoretical approach developed based on Griem and co-workers’ theory is used to evaluate Stark widths and shifts of all studied lines whenever required atomic energy levels data and transition probabilities are available. At the end of the text report, for each analyzed neutral or ion species, the information about the location of the same species data in preceding reviews is given.

Experimental investigation of electron-mercury atom collisions: insights into atomic interaction dynamics

This experiment aims to validate the Bohr’s model, which posits the existence of discrete energy levels within Hg and Ne atoms, through the Frank-Hertz experimental methodology. Utilizing two specialized tubes, one containing Neon gas and the other Mercury gas, electrons are accelerated to collide with the gas atoms. As the applied voltage is gradually increased, a distinct min-max pattern emerges on the current-voltage graph, with the equidistant minima and maxima, indicating the quantization of atomic energy levels, a phenomenon predicted by Bohr’s model. The experimentally determined distance between these peaks correlates with the energy required to excite the respective gas atoms to a higher energy state. The measured excitation energies – 16.58±2.36 eV for neon and 4.90±0.12 eV for mercury – align closely with the widely accepted energy levels for these atoms. These findings not only corroborate the quantized nature of atomic properties but also reinforce the validity of Bohr’s atomic model.

Opacities of singly and doubly ionized neodymium and uranium for kilonova emission modeling

ABSTRACT Even though the electromagnetic counterpart AT2017gfo to the binary neutron star merger GW170817 is powered by the radioactive decay of r-process nuclei, only few tentative identifications of light r-process elements have been made so far. One of the major limitations for the identification of heavy nuclei is incomplete or missing atomic data. While substantial progress has been made on lanthanide atomic data over the last few years, for actinides there has been less emphasis, with the first complete set of opacity data only recently published. We perform atomic structure calculations of neodymium (Z = 60) as well as the corresponding actinide uranium (Z = 92). Using two different codes [flexible atomic code (fac) and hartree–fock-relativistic (hfr)] for the calculation of the atomic data, we investigate the accuracy of the calculated data (energy levels and electric dipole transitions) and their effect on kilonova opacities. For the fac calculations, we optimize the local central potential and the number of included configurations and use a dedicated calibration technique to improve the agreement between theoretical and available experimental atomic energy levels (AELs). For ions with vast amounts of experimental data available, the presented opacities agree quite well with previous estimations. On the other hand, the optimization and calibration method cannot be used for ions with only few available AELs. For these cases, where no experimental nor benchmarked calculations are available, a large spread in the opacities estimated from the atomic data obtained with the various atomic structure codes is observed. We find that the opacity of uranium is almost double the neodymium opacity.

Electron Transfer in Contact Electrification under Different Atmospheres Packaged inside TENG.

Contact electrification (CE), a common physical phenomenon, is worth discussing. However, there are few reports on the influence of atmosphere on CE, or on the performance of triboelectric nanogenerators (TENG), based on CE by encapsulating gas inside. Here, we propose physical processes of electron transfer to interpret the impact of the gaseous atmosphere on CE. An atmosphere-filled triboelectric nanogenerator (AF-TENG) encapsulated five different gas-components of air based on the vertical contact separation mode was prepared. The sensitivity (1.02 V·N-1) and the power density (9.63 μW·m-2) of the oxygen-atmosphere-filled AF-TENG were 229.03% and 157.81% higher than these (0.31 V·N-1 and 3.84 μW·m-2) of the nitrogen-atmosphere-filled AF-TENG. As the oxygen atom possesses more atomic energy levels than other atoms, this could act as a "bridge" for more electrons to directly transfer between the two materials. The device package under different atmospheres could not only strengthen understanding of CE and improve the performance of TENG, but also be potentially applicable to prevent and control unnecessary damage caused by static electricity.

Electromagnetically Induced Transparent Electromagnetic Properties Based on Multimode Coupling

Metamaterials are a class of non-natural materials with special properties, the microstructure of which does not exist in nature. By artificially designing the structure of such materials, they can acquire electromagnetic properties that conventional materials in nature do not have. Electromagnetically induced transparency refers to the process of quantum interference effect between atomic energy levels in microscopic systems, which makes an energy-transmitting window appear in the original energy-absorbing region, simply put, a medium strongly absorbs a certain frequency of the light beam, and when another light beam is applied, the absorption of the first light beam by the medium will be greatly reduced or no longer absorbed. This phenomenon is called electromagnetically induced transparency, or EIT for short. In this paper, we combine the graphene material with the EIT structure to improve the manipulability of the EIT structure and obtain a controllable EIT structure based on the multi-mode coupled EIT extension.

Silicon surface characteristics in vibration-assisted machining process via molecular dynamics

This study investigates the impacts of vibration amplitude, vibration frequency, and sliding velocity on the characteristics of the machined silicon substrate. The results show that increasing the vibration amplitude increases atomic strain, stress, and kinetic energy distributions while decreasing subsurface damage thickness, potential energy distribution, and especially surface roughness. The surface roughness values are 7.5 Å, 6.4 Å, 6.9 Å, and 6.0 Å corresponding to vibration amplitude of 15 Å, 20 Å, 25 Å, and 30 Å. Moreover, increasing the vibration frequency results in increased atomic strain, stress, and kinetic energy levels. The surface roughness values are 7.1 Å, 7.1 Å, 6.5 Å, 6.4 Å, and 6.0 Å corresponding to the vibration frequencies of 16.7 GHz, 33.3 GHz, 50 GHz, 66.7 GHz, 100 GHz, and 200 GHz. Furthermore, increasing the sliding velocity lowers the surface quality of the silicon sample. The surface roughness values of the silicon substrate are 6.5 Å, 6.7 Å, 6.9 Å, 6.9 Å, and 7.1 Å corresponding to 50 m/s, 100 m/s, 150 m/s, 200 m/s, and 250 m/s. Improving the vibration amplitude and frequency while decreasing the sliding velocity improves surface quality by increasing the collision between the diamond tips and the substrate. Remarkably, the vibration movement of the diamond tips could leave wave marks on the substrate surface. In general, the optimal parameters that generate a good surface are 30 Å, 200 GHz, and 50 m/s.

Observation of Exceptional Points in Thermal Atomic Ensembles.

Exceptional points (EPs) in non-Hermitian systems have recently attracted wide interest and spawned intriguing prospects for enhanced sensing. However, EPs have not yet been realized in thermal atomic ensembles, which is one of the most important platforms for quantum sensing. Here we experimentally observe EPs in multilevel thermal atomic ensembles and realize enhanced sensing of the magnetic field for 1 order of magnitude. We take advantage of the rich energy levels of atoms and construct effective decays for selected energy levels by employing laser coupling with the excited state, yielding unbalanced decay rates for different energy levels, which finally results in the existence of EPs. Furthermore, we propose the optical polarization rotation measurement scheme to detect the splitting of the resonance peaks, which makes use of both the absorption and dispersion properties and shows an advantage with enhanced splitting compared with the conventional transmission measurement scheme. Additionally, in our system both the effective coupling strength and decay rates are flexibly adjustable, and thus the position of the EPs are tunable, which expands the measurement range. Our Letter not only provides a new controllable platform for studying EPs and non-Hermitian physics, but also provide new ideas for the design of EP-enhanced sensors and opens up realistic opportunities for practical applications in the high-precision sensing of magnetic field and other physical quantities.

CdS Covered with Ga-P Electron Exchange Membrane for Efficient Photocatalytic Hydrogen Prodection

Abstract: CdS is one of the best semiconductor photocatalysts. However, photocorrosion will occur when CdS takes part in the photocatalytic system. The general solution is to add sacrificial reagents to inhibit this phenomenon. Even so, it can not maintain the stability of CdS. In order to improve the stability and efficiency of CdS in pure water, Ga-P electron exchange membrane was designed to modify its surface. Under radiation of visible light, a significant increase can be observed in hydrogen production activity. In the absence of Pt as electron transfer agent, the modification of Ga-P realizes decomposition of pure water from zero to one. At the same time, the hydrogen production rate is increased about 5 times with Pt and catalytic life is greatly extended. Through proof of controlled experiment, Ga-P electron exchange membrane can not only prolong the lifetime of photogenerated electrons, but also change the direction of electrons. The formation of a protective membrane makes composite photocatalyst improve the stability and enhance the photocatalytic activity. Based on the analysis of TEM, fluorescence lifetime, UV-Vis diffuse reflection and photocurrent response, the mechanism is analyzed from atomic radius, nuclear orbit and energy level. For homogeneous electronic band structure and XPS analysis, we determined that the binary catalyst formed an S-scheme heterojunction. The work provides a potential way to design a more efficient and stable composite photocatalyst in the future. And contributed to the development of S-scheme heterojunctions.

Cascaded orbital–oriented hybridization of intermetallic Pd3Pb boosts electrocatalysis of Li-O2 battery

Catalysts with a refined electronic structure are highly desirable for promoting the oxygen evolution reaction (OER) kinetics and reduce the charge overpotentials for lithium-oxygen (Li-O2) batteries. However, bridging the orbital interactions inside the catalyst with external orbital coupling between catalysts and intermediates for reinforcing OER catalytic activities remains a grand challenge. Herein, we report a cascaded orbital-oriented hybridization, namely alloying hybridization in intermetallic Pd3Pb followed by intermolecular orbital hybridization between low-energy Pd atom and reaction intermediates, for greatly enhancing the OER electrocatalytic activity in Li-O2 battery. The oriented orbital hybridization in two axes between Pb and Pd first lowers the d band energy level of Pd atoms in the intermetallic Pd3Pb; during the charging process, the low-lying 4dxz/yz and 4dz2 orbital of the Pd further hybridizes with 2π* and 5σ orbitals of lithium superoxide (LiO2) (key reaction intermediate), eventually leading to lower energy levels of antibonding and, thus, weakened orbital interaction toward LiO2. As a consequence, the cascaded orbital-oriented hybridization in intermetallic Pd3Pb considerably decreases the activation energy and accelerates the OER kinetics. The Pd3Pb-based Li-O2 batteries exhibit a low OER overpotential of 0.45 V and superior cycle stability of 175 cycles at a fixed capacity of 1,000 mAh g-1, which is among the best in the reported catalysts. The present work opens up a way for designing sophisticated Li-O2 batteries at the orbital level.

New 26P(p, γ)27S Thermonuclear Reaction Rate and Its Astrophysical Implications in the rp-process

Accurate nuclear reaction rates for 26P(p, γ)27S are pivotal for a comprehensive understanding of the rp-process nucleosynthesis path in the region of proton-rich sulfur and phosphorus isotopes. However, large uncertainties still exist in the current rate of 26P(p, γ)27S because of the lack of nuclear mass and energy level structure information for 27S. We reevaluate this reaction rate using the experimentally constrained 27S mass, together with the shell model predicted level structure. It is found that the 26P(p, γ)27S reaction rate is dominated by a direct capture reaction mechanism despite the presence of three resonances at E = 1.104, 1.597, and 1.777 MeV above the proton threshold in 27S. The new rate is overall smaller than the other previous rates from the Hauser–Feshbach statistical model by at least 1 order of magnitude in the temperature range of X-ray burst interest. In addition, we consistently update the photodisintegration rate using the new 27S mass. The influence of new rates of forward and reverse reaction in the abundances of isotopes produced in the rp-process is explored by postprocessing nucleosynthesis calculations. The final abundance ratio of 27S/26P obtained using the new rates is only 10% of that from the old rate. The abundance flow calculations show that the reaction path 26P(p, γ)27S(β +,ν)27P is not as important as previously thought for producing 27P. The adoption of the new reaction rates for 26P(p, γ)27S only reduces the final production of aluminum by 7.1% and has no discernible impact on the yield of other elements.

Experimental and Theoretical Study of Dynamic Polarizabilities in the 5S1/2 – 5D5/2 Clock Transition in Rubidium-87 and Determination of Electric Dipole Matrix Elements

The interaction between light and an atom causes perturbations in the atom's energy levels, known as the light-shift. These light-shifts are a key source of inaccuracy in atomic clocks, and can also deteriorate their precision. We present a study of light-shifts and associated dynamic polarizabilities for a two-photon atomic clock based on the $5S_{1/2}$-$5D_{5/2}$ transition in rubidium-87 over the range 770 nm to 800 nm. We determine experimental and theoretical values for a magic wavelength in this range and the electric dipole (E1) matrix element for the $5P_{3/2}$-$5D_{5/2}$ transition. We find a magic wavelength of 776.179(5) nm (experimental) and 776.21 nm (theoretical) in the vicinity of the $5P_{3/2}$-$5D_{5/2}$ resonance, and the corresponding reduced E1 matrix element 1.80(6) $ea_0$ (experimental) and 1.96(15) $ea_0$ (theoretical). These values resolve a previous discrepancy between theory and experiment.

Mechanistic insight into active species formation during Fenton-like processes by regulating dissimilar charged groups on Fe3O4 nanospheres

Iron-mediated activation of peroxymonosulfate (PMS) had long been of great interest for the effective oxidation of micropollutants. However, how the chemical environment of iron oxides influence active species formation in heterogeneous Fenton processes was poorly understood. Herein, Fe3O4-X nanospheres (X = –NH2, –COOH) were synthesized for coordination chemical environment regulation. The DFT calculation showed the models of Fe3O4-X modified by –NH2 and –COOH in four-coordination and six-coordination environments. Among them, Fe3O4-COOH in four-coordination environment had the lowest formation energy and highest adsorption energy combined with PMS, with a most stable system. In the adsorption model of four-coordination Fe3O4-COOH, the d-orbitals and s-orbitals energy levels of Fe atoms underwent drastic changes compared with those before adsorption, H atoms on the carboxyl group and O atoms on the PMS formed a new HO– that attached to Fe atoms, with a strong coupling between them. The simulation results confirmed the proposed activation mechanism of Fe3O4-COOH activating PMS to generate SO4·- and HO–, and then partial SO4·- reacted with HO– to generate ·OH, and finally the two radicals attacked tetracycline (TC) together. In Fe3O4-COOH/PMS system, Fe3O4-COOH/PMS system can convert more Fe2+ into Fe3+, which also means that more Fe2+ reacts with PMS to produce Fe3+ and SO4·-. The TC degradation efficiency of the Fe3O4-COOH/PMS system was 93%, higher than that of the Fe3O4-NH2/PMS system after 30 min of reaction. Consequently, this work contributes to the mechanistic insight into active species regulation during Fenton-like processes by manipulating surface groups.