Emissivity: A Program for Atomic Transition Calculations

In this article we report the release of a new program for calculating emissivity and other physical parameters in atomic transition processes.The program,which can be downloaded with its documentation and a sample of input and output files from www.scienceware.net/id1.html,passed various rigorous tests and was used alongside R-matrix and Autostructure codes to generate theoretical data and analyze observational data.It is particularly useful for investigating atomic transition lines in astronomical context as the program is capable of generating a huge amount of theoretical data and comparing it to observational line list.A number of atomic transition algorithms and analytical techniques are implemented within the program and can be very useful in various situations.The program can be described as fast and efficient.Moreover,it requires modest computational resources.

Dimensionality and Finite Number Effect on BCS Transition of Atomic Fermi Gas

The effect of finite number and dimensionality has been discussed in thispaper. The finite number effect has a negative correction to final temperature for 2D or 3D atomicFermi gases. The changing of final temperature obtained by scanning from BEC region to BCS regionare 10% or so with N ≤ 10~3 and can be negligible when N 】 10~3. However, in ID atomic Fermi gas,the effect gives a positive correction which greatly changes the final temperature in Fermi gas.This behavior is completely opposed to the 2D and 3D cases and a proper explanation is still to befound. Dimensionality also has a positive correction, in which the more tightly trapping, the higherfinal temperature one gets with the same particle number. A discussion is also presented.

Imaging the crystal orientation of 2D transition metal dichalcogenides using polarization-resolved second-harmonic generation

We use laser-scanning nonlinear imaging microscopy in atomically thin transition metal dichalcogenides(TMDs)to reveal information on the crystalline orientation distribution,within the 2D lattice.In particular,we perform polarization-resolved second-harmonic generation(PSHG)imaging in a stationary,raster-scanned chemical vapor deposition(CVD)-grown WS2 flake,in order to obtain with high precision a spatially resolved map of the orientation of its main crystallographic axis(armchair orientation).By fitting the experimental PSHG images of sub-micron resolution into a generalized nonlinear model,we are able to determine the armchair orientation for every pixel of the image of the 2D material,with further improved resolution.This pixel-wise mapping of the armchair orientation of 2D WS2 allows us to distinguish between different domains,reveal fine structure,and estimate the crystal orientation variability,which can be used as a unique crystal quality marker over large areas.The necessity and superiority of a polarization-resolved analysis over intensity-only measurements is experimentally demonstrated,while the advantages of PSHG over other techniques are analysed and discussed.

Magnetism of Metals, Alloys and of Clusters of Transition Metal Atoms

A condition for local moment formation in metals derived by Stoddart and March (Ann. Phys. NY 1972 64, 174) is first used to discuss the ferromagnetism of body-centred-cubic Fe. A less detailed discussion is also added on Ni and Co. This leads into a treatment of the non- linear response of such 3d ferromagnets to dilute substitutional impurities. Antiferromagnets responding to local changes in the exchange field caused by such impurities are also studied, Mn in Cr being one such system discussed. The paper concludes with a brief summary of clusters of transition metal atoms, with most attention devoted to Cr and to Mn.

Effects of 3d-transition metal doping on the electronic and magnetic properties of one-dimensional diamond nanothread

The diamond nanothread(DNT), a new one-dimensional(1 D) full carbon sp3 structure that has been successfully synthesized recently, has attracted widespread attention in the carbon community. By using the first-principles calculation method of density functional theory(DFT), we have studied the effects of 3 d transition metal(TM) atomic doping on the electronic and magnetic properties of DNT. The results show that the spin-polarized semiconductor characteristics are achieved by doping Sc, V, Cr, Mn, and Co atoms in the DNT system. The magnetic moment ranges from 1.00 μB to 3.00 μB and the band gap value is from 0.35 e V to 2.54 e V. The Fe-doped DNT system exhibits spin-metallic state with a magnetic moment of 2.58 μB, while the Ti and Ni-doped DNT systems are nonmagnetic semiconductors. These results indicate that the 3 d TM atoms doping can modulate the electronic and magnetic properties of 1 D-DNT effectively, and the TM-doped DNT systems have potential applications in the fields of electronics, optoelectronics, and spintronics.

Tuning Martensitic Phase Transition by Non-Magnetic Atom Vacancy in MnCoGe Alloys and Related Giant Magnetocaloric Effect

The effects of non-magnetic atom vacancy on structural, martensitic phase transitions and the corresponding magnetocMoric effect in MnCoGel-x alloys are investigated using x-ray diffraction and magnetic measurements. The introduction of non-magnetic atom vacancy leads to the decrease of the martensitic transition temperature and realizes a temperature window where magnetic and martensitic phase transitions can be tuned together. Moreover, the giant magnetocaloric effect accompanied with the coupled magnetic-structural transition is ob- tained. It is observed that the peak values of magnetic entropy change of MnCoGeo.97 are about -13.9, -35.1 and -47.4J.kg-1K-1 for △H = 2, 5, 7T, respectively.

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.

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.

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.

Oscillator Strengths and Lifetimes for the P XIII Spectrum

The P XIII spectrum has been analyzed by several authors using different light sources. The semi-empirical oscillator strengths (gf) and the lifetimes presented in this work for all known P XIII spectral lines and energy levels were carried out in a multi-configuration Hartree-Fock relativistic (HFR) approach. In this calculation, the electrostatic parameters were optimized by a least-squares procedure in order to improve the adjustment of theoretical to experimental energy levels. The method produces gf-values that are in agreement with intensity observations and lifetime values closer to the experimental ones.

Ultrahigh-resolution nonlinear optical imaging of the armchair orientation in 2D transition metal dichalcogenides

We used nonlinear laser scanning optical microscopy to study atomically thin transition metal dichalcogenides(TMDs)and revealed,with unprecedented resolution,the orientational distribution of armchair directions and their degree of organization in the two-dimensional(2D)crystal lattice.In particular,we carried out polarization-resolved second-harmonic generation(PSHG)imaging for monolayer WS2 and obtained,with high-precision,the orientation of the main crystallographic axis(armchair orientation)for each individual 120×120 nm^(2) pixel of the 2D crystal area.Such nanoscale resolution was realized by fitting the experimental PSHG images,obtained with sub-micron precision,to a new generalized theoretical model that accounts for the nonlinear optical properties of TMDs.This enabled us to distinguish between different crystallographic domains,locate boundaries and reveal fine structure.As a consequence,we can calculate the mean orientational average of armchair angle distributions in specific regions of interest and define the corresponding standard deviation as a figure-of-merit for the 2D crystal quality.

Electrical and Corrosion Properties of Titanium Aluminum Nitride Thin Films Prepared by Plasma-Enhanced Atomic Layer Deposition

Titanium-aluminum-nitride（TiAlN） films were grown by plasma-enhanced atomic layer deposition（PEALD）on 316 L stainless steel at a deposition temperature of 200 °C. A supercycle, consisting of one AlN and ten TiN subcycles, was used to prepare TiAlN films with a chemical composition of Ti（0.25）Al（0.25）N（0.50）. The addition of AlN to TiN resulted in an increased electrical resistivity of TiAlN films of 2800 μΩ cm, compared with 475 μΩ cm of TiN films, mainly due to the high electrical resistivity of AlN and the amorphous structure of TiAlN. However, potentiostatic polarization measurements showed that amorphous TiAlN films exhibited excellent corrosion resistance with a corrosion current density of 0.12 μA/cm^2, about three times higher than that of TiN films, and about 12.5 times higher than that of 316 L stainless steel.

Electric Field Measurement and Application Based on Rydberg Atoms

Microwave sensing offers important applications in areas such as data communication and remote sensing.It has thus received much attention from academia,industry,and governments.Atomic wireless sensing uses the strong response of the large electric dipole moment of a Rydberg atom in response to an external field to achieve precise measurement of a radio frequency(RF)signal.This method offers advantages over traditional wireless sensing including ultrawide energy level transitions,which makes it responsive to RF electric fields over a wide bandwidth.Here,we briefly review the progress of electric field measurement based on Rydberg atoms.We discuss the properties of Rydberg atoms,measurement using Rydberg atoms,experimental progress in electric field measurement of different bands,and different methods for detecting electric fields(such as atomic superheterodyne,machine learning,and critically enhanced measurement).The development of Rydberg atomic measurement focuses on the advantages of Rydberg atomic sensing,especially when compared to conventional microwave receivers.This work is of major significance to developing Rydberg-based measurements in astronomy,remote sensing,and other fields.

Use of 2-(tert-butoxy)-N-(3-carbamothioylphenyl)acetamide and graphene oxide for separation and preconcentration of Fe(Ⅲ),Ni(Ⅱ),Cu(Ⅱ) and Zn(Ⅱ) ions in different samples

A simple and selective method using a column packed with graphene oxide（GO） as a solid phase extractant has been developed for the multi-element preconcentration of Fe（Ⅲ）,Ni（Ⅱ）,Cu（Ⅱ） and Zn（Ⅱ）ions prior to flame atomic absorption spectrometric determinations.The method is based on the sorption of mentioned ions on synthesized GO using 2-（tert-butoxy）-N-（3-carbamothioylphenyl）acetamide as a chelating agent.Several parameters on the extraction and complex formation were optimized.Under the optimized conditions（pH 6,flow rate 9 mL/min）,metal ions were retained on the column,then quantitatively eluted by HNO3solution（5 mL,3.0 mol/L）.The preconcentration factor was calculated as250.The detection limits for the analyte ions of interest were found in the range of 0.11 ng/mL（Ni2＋） to0.63 ng/mL（Cu2＋）.The column packed with GO was adequate for metal ions separation in matrixes containing alkali,alkaline earth,transition and heavy metal ions.

Interaction potential of two nonidentical ground-state atoms

We study the interaction potential of two nonidentical ground-state atoms coupled to a scalar field in a vacuum by separately calculating the contributions of vacuum fluctuations and those of the radiation reaction of the atoms.Both cases of atoms in a free space and in parallel or vertical alignment to a reflecting boundary are considered.For the former case,we find that the leading-order interaction potential in the regionλA?L?λB exhibits the same separationdependence as that in the region L?λA?λB,where L,λA andλB are respectively the interatomic separation and the transition wavelengths of two atoms withλA?λB.For the latter case,we find that boundary-induced modifications are very remarkable when L?z,with z characterizing the separation between the two-atom system and the boundary.Particularly,when L further satisfies L?λA and L?λB,the interaction potential in the parallel-and the verticalalignment cases respectively scales as z4L-7 and z2L-5,the L-dependence of which is one order higher than those of two atoms in regions where L?z and meanwhile L?λA or/and L?λB.Our results suggest that retardation for the interaction potential of two nonidentical atoms with remarkably distinctive transition frequencies happens only when the interatomic separation is much greater than the transition wavelengths of both atoms.

Theoretical catalytic performance of single-atom catalysts M_(1)/PW_(12)O_(40)for alkyne hydrogenation materials

Single-atom catalysts(SACs)have provoked significant curiosity in heterogeneous catalysis due to the benefits of maximum metal atoms usage,robust metal-support interaction,single-metal-atom active sites,and high catalytic efficiency.In this study,the electronic structures and catalytic mechanism of ethyne hydrogenation of SACs with the group-9 metal atoms M1(M1=Co,Rh,Ir)anchored on PTA(phosphotungstic acid)cluster have been explored by using first-principles quantum calculations.It is found that the catalytic activity of ethyne(C_(2)H_(2))hydrogenation is determined by two critical parameters:the adsorption energies of the adsorbate(H_(2),C_(2)H_(2))and the activation energy barrier of ethyne hydrogenation.We have shown that the reaction pathway of ethyne hydrogenation reaction on the experimentally characterized Rh1/PTA at room temperature consists of three steps:C_(2)H_(2) and H_(2) coadsorption on Rh1/PTA,H_(2) attacking C_(2)H_(2) to form C_(2)H_(4),then C_(2)H_(4) desorbing or further reacting with H_(2) to produce C_(2)H6 and completing the catalytic cycle.The Rh1/PTA possesses fair catalytic activity with a C_(2)H_(4) desorption energy of 1.46 eV and a 2.59 eV barrier for ethylene hydrogenation.Moreover,micro-kinetics analysis is also carried out to understand the mechanism and catalytic performance further.The work reveals that the PTA-supported SACs can be a promising catalyst for alkyne hydrogenation.