Binding Energy Of Atom Research Articles

Harmonic phase transition in solids under high pressures

The binding energy of atoms in substances exceeds the energy of the harmonic vibrator owing to the anharmonicity (Fig. 1). Experiments show reduction of the anharmonic component of binding energy in solids under high pressures. These data allow us to determine values of pressures when the coefficients of thermal expansions become equal to zero, i.e. when the harmonic phase transition occurs.

A study on the hydrogen storage performance of graphene–Pd(T)–graphene structure

The 1–6 H2 molecule adsorption energy and electronic properties of sandwich graphene–Pd(T)–Graphene (G–Pd(T)–G) structure were studied by the first-principle analysis. The binding energies, adsorption energies, and adsorption distances of Pd atoms-modified single-layer graphene and bilayer graphene with H2 molecules at B, H, T adsorption sites were calculated. In bilayer graphene, the adsorption properties at T sites were found to be more stable than those at B and H sites. The binding energy of Pd atoms (4.16 eV) on bilayer graphene was higher than the experimental cohesion energy of Pd atoms (3.89 eV), and this phenomenon eliminated the impact of metal clusters on adsorption properties. It was found that three H2 molecules were stably adsorbed on the G–Pd(T)–G structure with an average adsorption energy of 0.22 eV. Therefore, it can be speculated that G–Pd(T)–G is an excellent hydrogen storage material.

Two-dimensional single-layer PC6 as promising anode materials for Li-ion batteries: The first-principles calculations study

Very recently, single-layer (SL) PC6, which has buckled graphene-like structure and ultrahigh carrier mobility, was reported. In this paper, the properties of SL PC6 as anticathode material for Li-ion batteries have been studied by using the first-principle density functional theory. The most stable binding situationof the Li-atom in the SL PC6 is the P-atomic top position with C atom as the plane two flanks. The Fermi level of SL PC6 moves upward to the conduction band, indicating that SL PC6 transitions from semiconductor to metal after adsorption of the Li atom. At all the concentrations studied, the binding energy of Li atoms adsorbed on SL PC6 are negative, showing that the adsorption process is stable. Li-ions tend to diffuse along path I in SL PC6 and the diffusion path is small. The maximum theoretical specific capacity of SL PC6 as Li-ion batteries is 478.61 and 717.09 mAh/g for single and double side adsorption, respectively. In addition, the average open circuit voltage for single and double side adsorption is respectively 0.23 V and 0.21 V. Our research shows that SL PC6 is an appropriate Li-ion anticathode material.

Development of the numerical Hartree-Fock method for screened atoms with Debye-Hückel potential

SynopsisThe difficulties in developing the numerical Hartree-Fock programs for atoms interacting with screened Coulomb potential have been overcome. The binding energies of atoms for various screening parameters are obtained in high accuracy. C4+ ion is investigated to demonstrate the validity of our program.

Relativistic corrections to the binding energy of positronic alkali-metal atoms

We report a theoretical calculation of the relativistic corrections to the binding energy of positronic alkali-metal atoms. The ground state for the positronic alkali-metal atom is a loosely bound state with the structure of an alkali-metal ion surrounded by a positronium cloud. The correlation between the valence electron and positron in the field of a residual core ion is taken into account using a three-body model. Relativistic corrections to the binding energy for positronic alkali-metal atoms are evaluated based on the Breit-Pauli perturbation theory up to the second order of the fine structure constant. The relativistic corrections caused by the interaction between the valence electron and core ion was evaluated from the decomposed expectation values of the perturbation Hamiltonian. We found that the importance of relativistic corrections to the binding energy, namely the ratio of the net relativistic correction in the total binding energy, is remarkably enhanced in the loosely bound states of positronic alkali-metal atoms, where the charge of the valence electron is screened by the positron as positronium in the outermost region, while the electron is released from the positron near the nucleus. The results imply that positronic atoms with a dominant positronium can serve as an apt testing ground for relativistic quantum mechanics.

Investigation of the Nonstationary Energy Distribution of an Atomic Collision Cascade

In this paper, we derive a nonstationary distribution function describing the energy distribution of the cascade of moving atoms taking into account their multiplication. The function was derived by solving the Boltzmann kinetic equation. The development of the cascade was considered for the materials consisting of atoms of the same type without taking into account the binding energy of atoms at the crystal lattice sites. The scattering of moving atoms is assumed to be elastic and spherically symmetrical in a center-of-inertia system, and the interaction cross-section is assumed to be constant. The use of these assumptions allows us to derive simple analytic formulas for the nonstationary energy distribution function for the cascade and analyze its main distinctive features. The results obtained allow evaluating the accuracy of various approximate solutions.

Designing Catalytic Sites on Surfaces with Optimal H-Atom Binding via Atom Doping Using the Inverse Molecular Design Approach.

It remains a general challenge to computationally design optimal catalytic structures based on earth-abundant metals for hydrogenation. Here, we demonstrate an effective computational approach based on inverse molecular design to deterministically design optimal catalytic sites on the Cu(100) surface through the doping of Fe and/or Zn, and a stable Zn-doped Cu(100) surface was found with minimal binding energy to H atoms. By the calculations at the level of density functional theory, the optimized catalyst sites are verified to be valid on the Cu(100) surface in an infinite periodic system. We analyze the electronic structure cause of the optimal binding sites using the analysis of the density of states. In addition, we use a Cu29Zn3 atomic cluster, where such an optimum catalytic site is valid on the Cu(100) surface, to understand the role of doped Zn atoms on lowering the H atom binding energy. We found that in the atomic cluster, the atomic orbitals of surface Zn-atoms show less participation in the binding of H atoms, compared to the atomic orbitals of surface Cu atoms. Our study provides valuable chemistry insights on designing catalytic structures using earth-abundant metals, and it may lead to the development of novel Cu-based earth-abundant alloys in bulk, nanoparticles, atomic clusters, or single-atom catalysts for important catalytic applications such as lignin degradation or CO2 conversion.

Enhancement of corrosion resistance of a high Zn-yttrium aluminum alloy

The corrosion resistance of a high Zn (11 wt%) aluminum alloy was found to be significantly improved by 45% when doped with Y (solid solution limit 1.4 wt %), while the hardness of the material is only reduced by 3.5%. Although corrosion is frequently observed in the grain boundaries of high Zn aluminum alloys, it is not observed in the grain boundary of the Y-included alloys under current approach, in spite of the increased volume of grain boundary phases. The content of Mg and Zn decreased in the grain boundary precipitates as the Y content increases, leading to an increase of the corrosion potential of these grain boundary phases. The calculated atomic binding energies, diffusion energies and surface energies suggested that Y substitution has improved the binding forces between alloy elements Mg, Cu, Zn and Al, but has a different effect on Cr. The precipitates in grain boundaries appear to have converted from the Al-based solid solution into a more stable intermetallic compound of MgZn2-type.

A density functional study on geometries, electronic and photo sensitized surface properties of the fullerene-like BGe nanomaterials

Geometries associated with relative stabilities, infrared spectra, and energy gaps of the slightly deformed (Ge6B6)n (n = 2–10) nanocages are systematically investigated applying density functional theory. Particularly, the relative stabilities in terms of the calculated averaged atomic binding energies and fragmentation energies show that (GeB)36 cage has enhanced stability over other nanoclusters. Interestingly, (Ge6B6)n nanocages prefer to the sphere-like geometries with large inner hollow spaces. Moreover, the calculated energy gaps of (Ge6B6)n nanocages are decreased generally and the wavelengths of absorption spectra in sphere-like (Ge6B6)n clusters are elongated with the increased size of (Ge6B6)n nanocages. The quantum confinement effect indirectly is revealed; furthermore, the nanosized (GeB)36-60 cages have a very stronger capacity for solar energy absorption or conversion due to narrow energy gaps and large DOS near LUMO and HOMO levels. Additionally, germanium atoms transfer electronic charges to their surrounding boron atoms, charge-transfers between Ge and B enhance stabilities of the nanocages. SH2 gas is sensitive to GeB cage and can be used to removal SH2 from air.

Influence of hydrogen supply on Mo(C,N) films synthesized by plasma-enhanced chemical vapor deposition using bis(tert‑butylimido) bis(dimethylamido) molybdenum

Complex composites of Mo(C,N) are deposited at temperatures of 150 °C and a working pressure of 1.3 Pa by plasma-enhanced chemical vapor deposition using bis(tert‑butylimido) bis(dimethylamido) molybdenum as precursor, argon as carrier gas to transport the vapors of the liquid metal–organic precursor at 80 °C, and hydrogen gas as reactant. The effect of hydrogen as reactive gas in the deposition process is investigated. For plasma generation in the plasma cleaning and deposition process, pulsed DC plasma is utilized at a negative voltage of 600 V with a frequency of 150 kHz and a pulse reversal time of 1 μs. As a result, hydrogen ambient decreases the depositio rate and surface roughness and increases the hardness of the films. Under the flow rate condition of hydrogen gas over 300 sccm, the hardness reaches high values over 26 GPa, and the adhesion is over 30 N. X-ray diffraction spectroscopy measurements reveal hexagonal phased molybdenum carbide as the preferred crystallization of the Mo(C,N) films, and nanocrystalline molybdenum nitride is mixed with the molybdenum carbide. Analysis of the chemical binding of the Mo(C,N) films by X-ray photoelectron spectroscopy and Raman spectroscopy shows that the dominant binding state is the molybdenum carbide, amorphous graphitic carbon and carbon nitride composites are identified from the evaluation of the binding energy of carbon atoms.

Replacing Petrov's process with atmospheric flotation using Pb-BHA complexes for separating scheelite from fluorite

It is difficult to separate scheelite especially from fluorite with fatty acid collectors because the adsorption mechanism of these collectors occurs through chemisorption of the oleate ion onto the mineral surface. A simplified flotation process using Pb-BHA complexes was developed to replace the energy-inefficient Petrov’s process of using a fatty acid, increasing the recovery of scheelite and reducing the cost. The relationship between surface chemical properties (crystal chemistry, solubility, and Zeta potential) of minerals and flotation by using a fatty acid or Pb-BHA complexes was studied in detail to provide new insights into the selective separation mechanism. The results indicate that the scheelite surface exposes more O atoms than Ca and that they are negatively charged due to the anisometric dissolution of Ca and WO4, which provides the possibility for separation using selective interfacial reaction. The Fourier Transform infrared spectroscopy (FTIR) and Zeta potential results indicate that both chemical and electrostatic adsorption play an important role in the adsorption of Pb-BHA complexes on the scheelite surface. The X-ray photoelectron spectroscopy (XPS) results of the atomic composition and binding energies confirmed the presence of the adsorbed Pb-BHA complexes and that Pb, O and Ca may be the active adsorption sites. Therefore, scheelite was able to be collected by forming either a Ca-O-Pb-collector or W-O-Pb-collector (BHA). However, fluorite was only able to be collected by a fatty acid collector and colloidal [H2SiO3]n−, and a high temperature was needed improve the selective desorption of the adsorbed fatty acid collector by forming Ca-[H2SiO3]n− on the fluorite surface, resulting in serious problems in industry. However, the Pb-BHA complexes significantly contribute to improving the recovery of scheelite minerals, simplifying the flotation process, and circulation of the residual reagents and water.

ATP Mimics pH-Dependent Dual Peroxidase-Catalase Activities Driving H 2 O 2 Decomposition

Adenosine triphosphate (ATP) is produced mainly in the mitochondrion, and its primary task is to function as a ubiquitous energy currency to meet the cellular metabolic demands in biological system...

Revisiting surface core-level shifts for ionic compounds

The shifts of core-level binding energies can provide powerful information about the electronic structure of a material. Understanding the physical origin of these shifts for catalytically relevant oxides may provide important insight into their properties. This requires reliable theoretical methods which are able to relate the binding energy shifts to the electronic structure. In order to establish such a methodology, the CaO(100) surface to bulk core-level binding energy shifts have been studied with Hartree-Fock and density-functional theory methods using both cluster and periodic slab models. The shifts obtained from the different theoretical methods are compared with each other and with data from synchrotron-based x-ray photoelectron spectroscopy (XPS) measurements. With a common approximation for the slab model treatment of XPS, the predicted binding energy shifts are seriously in error. The origin of the error is identified as arising from a flawed treatment of the surface atom binding energies, and a method for correcting the failure is presented.

Polyhedral oligomeric silsesquioxane-based aliphatic polyester composites: Synthesis, characterization, and investigation of thermal properties

In this article, polyhedral oligomeric silsesquioxane (POSS)-containing aliphatic polyester composites were synthesized using condensation polymerization. Firstly, a series of polyesters have been prepared from malonic acid, succinic acid, adipic acid, sebacic acid (diacids), and 1,4-butanediol. On the other step of this study, polyester composites were synthesized between 1,2-propanediolisobutyl POSS (POSS-Diol) and diacid. For comparison, the same reaction was repeated in the presence of 1,4-butanediol, POSS-Diol, and diacids. The resulting samples were characterized by proton nuclear magnetic resonance, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy. Thermal behaviors of molecules were analyzed using thermogravimetry (TG) analysis. Molecular weights of synthesized polymers were determined with gel permeation chromatography (GPC). The XPS results indicate that the POSS hybrid molecule was successfully incorporated into the polyester structure. The characteristic binding energies of organic silicium atoms and Si–O were observed at 102 eV and 104 eV, respectively. According to the results from GPC, POSS-containing polyester composites (POSS-Diol + diacid + 1,4-butanediol) have higher molecular weight. The number-average molecular weights ( Mn) of polyester composites b1,b2,b3, and b4 are found to be 6800 g/mol, 7050 g/mol, 7200 g/mol, and 7250 g/mol, respectively. TG results show that the resistance to thermal degradation of POSS-containing polymer bonds is not strong as expected. The results support that the synthesized POSS-based polyesters can be used as high-performance commercial polymers.

Growth of carbon nanosheets on carbon nanotube arrays for the fabrication of three-dimensional micro-patterned supercapacitors

Micro-supercapacitors provide high peak power, long cycle life, and high charge/discharge rates for practical applications in microsystems. However, current micro-supercapacitors generally suffer from low energy density and complicated fabrication process. Here, we report carbon nanosheet (CN) selectively grown on carbon nanotube (CNT) patterns as three-dimensional hybrid electrodes for high-performance micro-supercapacitor applications. The growth mechanism is revealed that CNs prefers to grow on CNT surface rather than on SiO2 substrate due to the high binding energy of carbon atom absorbed on CNT surface. The symmetric all-carbon CN/CNT micro-supercapacitors exhibit ultrahigh areal capacitance of approximately 110 mF cm−2 at a current density of 0.3 mA cm−2, outstanding long-term cyclic stability (≈7% loss of initial capacitance after 10,000 cycles). Furthermore, flexible microsupercapacitors are achieved by peeling off microelectrodes using H3PO4/PVA electrolyte and showing high functional flexibility (capacitance loss less than 9% after 100-cyclic bending tests). The outstanding electrochemical performance and functional flexibility of present micro-supercapacitors show great potential applications in smart and miniaturized electronic devices.

Atomic binding energies for the ground state of some helium-like hypernuclear atoms

In a hypernuclear atom one or more hyperons are present in the nucleus, in addition to nucleons. The atomic properties of such exotic systems have not been rigorously studied contrary to their nuclear properties. The presence of a hyperon inside the nucleus modifies the nuclear charge, mass and strangeness. This results in changes in the electromagnetic interaction between the nucleus and its electrons, and consequently on the spectral lines of the atom. For a few helium-like hypernuclear atoms we calculate the binding energies of the ground state, treating the atom as a three-body system. The nonrelativistic Schrödinger equation is solved for the three-body Coulombic system consisting of the finite-mass nucleus and its two electrons. We measure the effect of hyperon charge on the binding energy and electronic correlation. Quantum effects of the motion of the nucleus are taken into account in these calculations.

Fisher information of radial wavefunctions for relativistic hydrogenic atoms

We calculate Fisher information and the inverse participation ratio normalised by the electric binding energy for the relativistic hydrogenic atoms based on the radial wavefunctions in position space. Fisher information rapidly decreases as the atomic number increases, but it increases again for heavy atoms for S1/2 and P1/2 states due to the relativistic effect. We consider not only the ground state but also excited states by numerically evaluating the generalised Laguerre polynomials in the exact Dirac’s relativistic radial wavefunctions. This study contrasts with the previous studies of the relativistic many-electron systems (i.e., ground-state neutral atoms), where numerical densities were employed.

Infrared and mechanical properties of the oxygen-doped non-hydrogenated diamond-like carbon film prepared by pulsed laser deposition

The non-hydrogenated diamond-like carbon films were prepared by the femtosecond laser in the oxygen atmosphere, and the influence of the oxygen atmosphere on the microstructural, surface, infrared and mechanical properties of the oxygen-doped diamond-like carbon films were researched. The oxygen atmosphere was propitious to reduce the granules on the surfaces but increase the surface roughness of the diamond-like carbon DLC films. During the pulsed laser deposition, the carbon and oxygen atoms were inclined to form the CO bond, CO bond and CC hybridized bond, when the oxygen pressure was lower than 5 m Torr. Although the CO and CO bonds led one additional absorption band and two additional absorption peaks in the infrared spectra of the oxygen-doped diamond-like carbon films, their transmission in the medium infrared band increased. Nano-hardness of the DLC films was reduced when the oxygen pressure increased dominantly because the CC sp3 bonds with higher atomic binding energy were replaced the CO bonds with lower atomic binding energy.

QED theory of the specific mass shift in few-electron atoms

The quantum electrodynamics formalism to treat the interelectronic-interaction correction of first order in $1/Z$ to the two-electron part of the nuclear recoil effect on binding energies in atoms and ions is developed. The nonperturbative in $\alpha Z$ calculations of the corresponding contribution to the energies of the $1s^2$ state in He-like and the $1s^2 2s$ and $1s^2 2p_{1/2}$ states in Li-like ions are performed in the range $Z=5-100$. The behavior of the two-electron part of the nuclear recoil effect beyond the lowest-order relativistic approximation as $Z$ grows is studied.

Plasma corrosion resistance of aluminosilicate glasses containing Ca, Y and B under fluorocarbon plasma with Ar+

In this study, the corrosion resistance of alumino-silicate glass containing Ca, Y and B is assessed against CF4/O2/Ar plasma, with the results compared to those of poly-crystalline and single-crystalline alumina. All of the alumino-silicate glasses containing Ca, Y and B were more resistant than sintered alumina to a plasma-etching gas. Glass samples with boron oxide were less corroded by plasma than those without B2O3, and their surfaces were contaminated by the CFx generated by the plasma reaction.CaO-Y2O3-Al2O3-SiO2 (CYAS) showed a lower etch rate than sapphire and retained a smooth surface microstructure, unlike sintered alumina. The plasma resistance improved with an increase in the calcium oxide content. The improved plasma resistance of CYAS glass is thought to be due to the high sublimation temperature of the calcium fluoride and the strong atomic binding energy of the calcium ions in the glass.