Determination of a Safe Distance for Atomic Hydrogen Depositions in Hot-Wire Chemical Vapour Deposition by Means of CFD Heat Transfer Simulations

A heat transfer study was conducted,in the framework of Computational Fluid Dynamics(CFD),on a Hot-Wire Chemical Vapour Deposition(HWCVD)reactor chamber to determine a safe deposition distance for atomic hydrogen produced by HWCVD.The objective of this study was to show the feasibility of using heat transfer simulations in determining a safe deposition distance for deposition of this kind.All CFD simulations were set-up and solved within the framework of the CFD packages of OpenFOAM namely;snappyHexMesh for mesh generation,buoyantSimpleFoam and rhoSimpleFoam as the solvers and paraView as the post-processing tool.Using a standard set of deposition parameters for the production of atomic hydrogen by HWCVD,plots of the gas temperature in the deposition region were produced.From these plots,we were able to determine a safe deposition distance in the HWCVD reactor to be in the range between 3 and 4 cm from the filament.

Semiclassical and Quantum-Mechanical Formalism Applied in Calculating the Emission Intensity of the Atomic Hydrogen

The energy spectrum of the hydrogen atom has been applied in calculating the time rate of energy transitions between the quantum states of the atom. The formal basis of the approach has been provided by the quantum properties of energy and time deduced from the Joule-Lenz law. The rates of the energy transitions obtained in this way were compared with the quantum-mechanical probabilities of transitions calculated earlier by Bethe and Condon and Shortley for the same pairs of the quantum states.

Formation and Transport of Atomic Hydrogen in Hot-Filament Chemical Vapor Deposition Reactors

In this paper we focus on diamond film hot-filament chemical vapor deposition reactors where the only reactant is hydrogen so as to study the formation and transport of hydrogen atoms. Analysis of dimensionless numbers for heat and mass transfer reveals that thermal conduction and diffusion are the dominant mechanisms for gas-phase heat and mass transfer, respectively. A simplified model has been established to simulate gas-phase temperature and H concentration distributions between the filament and the substrate. Examination of the relative importance of homogeneous and heterogeneous production of H atoms indicates that filament-surface decomposition of molecular hydrogen is the dominant source of H and gas-phase reaction plays a negligible role. The filament-surface dissociation rates of H2 for various filament temperatures were calculated to match H-atom concentrations observed in the literature or derived from power consumption by filaments. Arrhenius plots of the filament-surface hydrogen dissociation rates suggest that dissociation of H2 at refractory filament surface is a catalytic process, which has a rather lower effective activation energy than homogeneous thermal dissociation. Atomic hydrogen, acting as an important heat transfer medium to heat the substrate, can freely diffuse from the filament to the substrate without recombination.

First Neutral Atomic Hydrogen Images of Quasar Host Galaxies

Violent galactic encounters or mergers are the leading contenders for triggering luminous quasar activity at low redshifts: such interactions can lead to the concentration of gas in the host galactic nucleus, thus fueling the suspected central superrmassive black hole. Although optical images show a number of violently interacting systems, in many cases the evidence for such interactions is only circumstantial (e.g., asymmetric optical morphologies, projected nearby companion galaxies) or not at all apparent. Here we image quasar host galaxies for the first time in the redshifted 21 cm line emission of neutral atomic hydrogen (HI) gas, which in nearby galaxies has proven to be a particularly sensitive as well as enduring tracer of tidal interactions. The three quasars studied have different optical environments normally seen around low reshift quasars, ranging from a perhaps mildly interacting system to a relatively undisturbed host with a projected neighbouring galaxy to an isolated and apparently serene host galaxy. By contrast with their optical appearences, all three quasar host galaxies exhibit ongoing or remnant tidal HI disruptions tracing galactic encounters or mergers. These observations provide a better understanding of the likely stage of their interaction.

Bohr’s Spectrum of Quantum States in the Atomic Hydrogen Deduced from the Uncertainty Principle for Energy and Time

A modified uncertainty principle coupling the intervals of energy and time can lead to the shortest distance attained in course of the excitation process, as well as the shortest possible time interval for that process. These lower bounds are much similar to the interval limits deduced on both the experimental and theoretical footing in the era when the Heisenberg uncertainty principle has been developed. In effect of the bounds existence, a maximal nuclear charge Ze acceptable for the Bohr atomic ion could be calculated. In the next step the velocity of electron transitions between the Bohr orbits is found to be close to the speed of light. This result provides us with the energy spectrum of transitions similar to that obtained in the Bohr’s model. A momentary force acting on the electrons in course of their transitions is estimated to be by many orders larger than a steady electrostatic force existent between the atomic electron and the nucleus.

A preliminary experiment of determining the geopotential difference using two hydrogen atomic clocks and TWSTFT technique

General relativity theory(GRT)concludes that a precise clock ticks at different running rates if it is under the influence of different geopotentials.Therefore,by comparing the running rates of clocks at arbitrary two stations,the geopotential difference between them can be determined.In this study,with the help of two hydrogen atomic clocks(noted as H-masers),using the two-way satellite time and frequency transfer(TWSTFT)technique,we carried out experiments of the geopotential difference determination at the China Aerospace Science&Industry Corporation(CASIC),Beijing.Here the ensemble empirical mode decomposition(EEMD)method is adopted to remove periodic signals included in the original observations.Finally,the clock-comparison-determined geopotential difference in the experiments is determined.Results show that the difference between the geopotential difference determined by GRT and that determined by measuring tape is about 1316.1±931.0 m2s-2,which is equivalent to 134.3±95.0 m in height,and in consistence with the stability of the H-masers applied in the experiments(at the level of10-15/day).With the rapid improvement of atomic clocks’accuracy,the geopotential determination by accurate clocks is prospective,and it is promising to realize the unification of the world vertical height system(WVHS).

Interaction of intense laser pulses with hydrogen atomic clusters

The interaction between intense femtosecond laser pulses and hydrogen atomic clusters is studied by a simplified Coulomb explosion model. The dependences of average proton kinetic energy on cluster size, pulse duration, laser intensity and wavelength are studied respectively. The calculated results indicate that the irradiation of a femtosecond laser of longer wavelength on hydrogen atomic clusters may be a simple, economical way to produce highly kinetic hydrogen ions. The phenomenon suggests that the irradiation of femtosecond laser of longer wavelength on deuterium atomic clusters may be easier than that of shorter wavelength to drive nuclear fusion reactions. The product of the laser intensity and the squared laser wavelength needed to make proton energy saturated as a function of the squared cluster radius is also investigated. The proton energy distribution calculated is also shown and compared with the experimental data. Our results are in agreement with the experimental results fairly well.

Electron Spin and Proton Spin in the Hydrogen and Hydrogen-Like Atomic Systems

The mechanical angular momentum and magnetic moment of the electron and proton spin have been calculated semiclassically with the aid of the uncertainty principle for energy and time. The spin effects of both kinds of the elementary particles can be expressed in terms of similar formulae. The quantization of the spin motion has been done on the basis of the old quantum theory. It gives a quantum number n = 1/2 as the index of the spin state acceptable for both the electron and proton particle. In effect of the spin existence the electron motion in the hydrogen atom can be represented as a drift motion accomplished in a combined electric and magnetic field. More than 18,000 spin oscillations accompany one drift circulation performed along the lowest orbit of the Bohr atom. The semiclassical theory developed in the paper has been applied to calculate the doublet separation of the experimentally well-examined D line entering the spectrum of the sodium atom. This separation is found to be much similar to that obtained according to the relativistic old quantum theory.

Research on frequency-temperature compensated sapphire-SrTiO_3 loaded cavity for hydrogen maser

To obtain frequency-temperature compensation in a sapphire loaded cavity for hydrogen maser, a dielectric named SrTiO3 is employed whose temperature coefficient of permittivity is opposite to that of sapphire. Based on theoretical analysis and computer simulation, a TE011 mode of a sapphire loaded cavity associated with two small rings of SrTiO3 with different thickness is solved, and the useful parameters that influence the temperature coefficient of cavity are calculated. Finally an experiment is brought forward and its results are very close to the computing results. When the thickness of SiTiO3 dielectric is 7 mm and the diameter is 17 mm in configuration b, the temperature coefficient of cavity is decreased from -58.8 kHz/K to -8.2 kHz/K and the quality factor is 40248.

Emission Intensity in the Hydrogen Atom Calculated from a Non-Probabilistic Approach to the Electron Transitions

Quantum aspects of the Joule-Lenz law for the transmission of energy allowed us to calculate the time rate of energy transitions between the quantum states of the hydrogen atom in a fully non-probabilistic way. The calculation has been extended to all transitions between p and s states having main quantum numbers not exceeding 6. An evident similarity between the intensity pattern obtained from the Joule-Lenz law and the corresponding quantum-mechanical transition pro-babilities has been shown.

Resonances of a hydrogen atom in strong parallel electric and magnetic fields using B-spline basis sets

The B-spline basis set plus complex scaling method is applied to the numerical calculation of the exact resonance parameters Er and Г/2 of a hydrogen atom in parallel electric and magnetic fields. The method can calculate the ground and higher excited resonances accurately and efficiently. The resonance parameters with accuracies of 10^-9 - 10^-12 for hydrogen atom in parallel fields with different field strengths and symmetries are presented and compared with previous ones. Extension to the calculation of Rydberg atom in crossed electric and magnetic fields and of atomic double excited states in external electric fields is discussed.

Magic Wavelengths for the 1S-2S and 1S-3S Transitions in Hydrogen Atoms

The dynamic dipole polarizabilities for 1S, 2S and 3S states of the hydrogen atom are calculated using the finite B-spline basis set method, and the magic wavelengths for 1S-2S and 1S-3S transitions are identified. In comparison of the solutions from the Schr6dinger and Dirac equations, the relativistic corrections on the magic wavelengths are of the order of 10-2 nm. The laser intensities for a 300-Er-deep optical trap and the heating rates at 514 and 1371 nm are estimated. The reliable prediction of the magic wavelengths would be helpful for the experimental design on the optical trapping of the hydrogen atoms, and in turn, it would be helpful to improve the accuracy of the measurements of the hydrogen 1S-2S and 1S-3S transitions.

Time Intervals of the Electron Transitions between the Energy States in the Hydrogen Atom Calculated in a Non-Probabilistic Way

Definitions of the mechanical parameters entering the Bohr model of the hydrogen atom allowed us to calculate the time intervals connected with the electron transitions between the nearest-neighbouring energy levels in the atom. This is done in a strictly non-probabilistic way. The time results are compared with those derived earlier on the basis of the classical Joule-Lenz law for the energy emission adapted to the case of the electron transfer in the quantum systems. A similar formalism has been next applied to the harmonic oscillator and a particle moving in the one-dimensional potential box.

Hydrogen Atom and Equivalent Form of the Lévy-Leblond Equation

We discuss the equivalent form of the Ldvy-Leblond equation such that the nilpotent matrices are two-dimensional. We show that this equation can be obtained in the non-relativistic limit of the （2＋1）-dimensional Dirac equation. Phrthermore, we analyze the case with four-dimensional matrices, propose a Hamiltonian for the equation in （3＋1） dimensions, and solve it for a Coulomb potential The quantized energy levels for the hydrogen atom are obtained, and the result is consistent with the non-relativistic quantum mechanics.

Resolution in the Case of the Hydrogen Atom of an Improved Dirac Equation

The improved Dirac equation is completely solved in the case of the hydrogen atom. A method of separation of variables in spherical coordinates is used. The angular functions are the same as with the linear Dirac equation: they account for the spin 1/2 of the electron. The existence of a probability density governs the radial equations. This gives all the quantum numbers required by spectroscopy, the true number of energy levels and the true levels obtained by Sommerfeld’s formula.

Christoffel Symbols and Chiral Properties of the Space-Time Geometry for the Atomic Electron States

Quantum electron states, in the case of an improved Dirac equation, are linked to the Christoffel symbols of the connection of space-time geometry. Each solution of the wave equation, in the case of the hydrogen atom induces a connection which is completely calculated. This allows us to discover the global and chiral properties of the space-time connection, with spin 2.

Quasi-Relativistic Description of Hydrogen-Like Atoms

Using a novel wave equation, which is Galileo invariant but can give precise results up to energies as high as mc2, exact quasi-relativistic quantum mechanical solutions are found for the Hydrogen atom. It is shown that the exact solutions of the Grave de Peralta equation include the relativistic correction to the non-relativistic kinetic energies calculated using the Schrödinger equation.

The Quantum Condition That Should Have Been Assumed by Bohr When Deriving the Energy Levels of a Hydrogen Atom

Bohr assumed a quantum condition when deriving the energy levels of a hydrogen atom. This famous quantum condition was not derived logically, but it beautifully explained the energy levels of the hydrogen atom. Therefore, Bohr’s quantum condition was accepted by physicists. However, the energy levels predicted by the eventually completed quantum mechanics do not match perfectly with the predictions of Bohr. For this reason, it cannot be said that Bohr’s quantum condition is a perfectly correct assumption. Since the mass of an electron which moves inside a hydrogen atom varies, Bohr’s quantum condition must be revised. However, the newly derived relativistic quantum condition is too complex to be assumed at the beginning. The velocity of an electron in a hydrogen atom is known as the Bohr velocity. This velocity can be derived from the formula for energy levels derived by Bohr. The velocity v of an electron including the principal quantum number n is given by αc/n. This paper elucidates the fact that this formula is built into Bohr’s quantum condition. It is also concluded in this paper that it is precisely this velocity formula that is the quantum condition that should have been assumed in the first place by Bohr. From Bohr’s quantum condition, it is impossible to derive the relativistic energy levels of a hydrogen atom, but they can be derived from the new quantum condition. This paper proposes raising the status of the previously-known Bohr velocity formula.

Highly selective/enantioselective Pt-ReOx/C catalyst for hydrogenation of L-malic acid at mild conditions

The catalyst preparation strategy was based on a strict introduction sequence of rhenium and platinum precursors and their strong interaction with carbon support resulted in the formation of 0.5 nm Pt-Re Ox species of atomic dispersion, where platinum is metallic, while monolayer rhenium is partially oxidized（Re2＋）. The reaction kinetics was studied taking into account the process of L-malic acid association leading to the formation of inactive cyclic oligomeric species. High TOFs（ca. 50 h-1）, selectivities（ca. 99%）and stability of Pt-Re Ox/C catalysts in aqueous-phase hydrogenation of L-malic acid, which are close to those of the homogeneous pincer type complexes, were revealed at mild conditions（T = 90–130 ℃）. Taking into account that（i） hydrogenation reaction occurred 2–3 orders of magnitude faster than its racemization and（ii） association of L-malic acid dominates at low temperatures and in a concentrated solution,special reaction conditions that allow obtaining chemically and optically（ee 〉 99%） pure（S）-3-hydroxy-γ-butyrolactone and（S）-1,2,4-butanetriol were found. Basing on HAADF-STEM, EDX, XPS, and kinetic studies, the structure of active species and basic reaction pathways are proposed.

Molecular Structure of Atomic Nucleus

In this work, we extend our work on the Heisenberg model of the neutron formulated as a dwarf hydrogen-like atom under the influence of the More General Exponential Screened Coulomb Potential (MGESCP) to show that an atomic nucleus may possess a molecular structure made up of atoms bonding together by a potential used to describe the strong force associated with a generalised Yukawa MGESCP potential. We show that the neutrons and protons are arranged into narrow lattices therefore they may fold to form three-dimensional shells by bonding similar to hydrogen bonding. In particular, the nucleons may form stable structures such as that of fullerenes in which the vertices are occupied by the nucleons which are simply just protons. For example, a nucleus with a total number of 60 nucleons may arrange itself into the topological structure of a buckminsterfullerene. We also apply Schrödinger wave equation with central field approximation to describe the quantum dynamics of nuclei of atomic atoms that now possess the physical structure of a dwarf molecular ion.