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Quantum-chemistry methods in the time domain with Gaussian basis sets are increasingly used to compute high-harmonic generation (HHG) spectra of atomic and molecular systems. The quality of these approaches is limited by the accuracy of Gaussian basis sets to describe continuum energy states. In the literature, optimal-continuum Gaussian basis sets have been proposed: Kaufmann et al. [J. Phys. B: At., Mol. Opt. Phys. 22, 2223 (1989)], Woźniak et al. [J. Chem. Phys. 154, 094111 (2021)], Nestmann and Peyerimhoff [J. Phys. B: At., Mol. Opt. Phys. 23, L773 (1990)], Faure et al. [Comput. Phys. Commun. 144, 224 (2002)], and Krause et al. [J. Chem. Phys. 140, 174113 (2014)]. In this work, we have compared the performances of these basis sets to simulate HHG spectra of H atom at different laser intensities. We have also investigated different strategies to balance basis sets with these continuum functions, together with the role of angular momentum. To quantify the performance of the different basis sets, we introduce local and global HHG descriptors. Comparisons with the grid and exact calculations are also provided. [ABSTRACT FROM AUTHOR]

We present a method to compute the photoionization spectra of atoms and molecules in linear-response, time-dependent density functional theory. The electronic orbital variations corresponding to ionized electrons are expanded on a basis set of delocalized functions, obtained as the solution of the inhomogeneous Helmholtz equation, with gaussian basis set functions as the right-hand side. The resulting scheme is able to reproduce the photoionization spectra without any need for artificial regularization or localization. We demonstrate that this Green's function-based approach is able to produce accurate spectra for semilocal exchange-correlation functionals, even using relatively small standard gaussian basis sets. [ABSTRACT FROM AUTHOR]

We investigate the effects of spatially non-uniform radio-frequency electric (E) field amplitudes on the spectral line shapes of electromagnetically induced transparency (EIT) signals in Rydberg atomic systems used in electrometry (i.e., the metrology of E-field strengths). Spatially non-uniform fields distort the EIT spectra from that of an ideal case, and understanding this distortion is important in the development of Rydberg atom-based sensors, as these distortions can limit accuracy and sensitivity. To characterize this distortion, we present a model that approximates the atom vapor as multi-layered media and then uses Beer's law to combine the absorption through its many discrete thin segments. We present a set of expected line distortions caused by various RF electric-field distributions found in practice. This provides an intuitive diagnostic tool for experiments. We compare this model to measured experimental atomic spectra in both two-photon and three-photon excitation schemes in the presence of non-uniform radio-frequency fields. We show that we can accurately model and reproduce the EIT lineshape distortion observed in these experimental data. [ABSTRACT FROM AUTHOR]

In this article, we present a simulation study of the linear and nonlinear spectroscopy of dense atomic vapors. Motivated by recent experiments, we focus on double quantum spectroscopy, which directly probes dipole–dipole interactions. By explicitly including thermal velocity, we show that temperature has an important impact on the self-broadening mechanisms of the linear and nonlinear spectra. We also provide analytical expressions for the response functions in the short time limit using the two-body approximation, which shows that double quantum spectroscopy for atomic vapors directly probes the transition amplitude of the electronic excitation between two atoms. We also propose an expression for the double quantum spectrum that includes the effect of Doppler broadening, and we discuss the effect of density on the spectrum. We show that when Doppler broadening is negligible compared to self-broadening, the double quantum spectrum scales with the atomic density, while when Doppler broadening dominates, it scales as the square of the density. [ABSTRACT FROM AUTHOR]

In this paper, electronic properties of Janus MSX monolayers (M = Mo, W; X = Se or Te), including electron energy loss near edge structures (ELNES), as K and L2,3 edge spectra of sulfur atoms, have been calculated using a full potential scheme and the augmented plane wave plus local orbitals (APW+lo) method in the framework of density functional theory (DFT). Due to the lack of experimental results, the obtained spectra are compared with the corresponding spectra of MoS2 monolayer. The band structure analysis shows that the Janus MoSSe and WSSe monolayers are direct bandgap semiconductors, while the Janus MoSTe and WSTe monolayers are indirect bandgap semiconductors. In comparison to MoS2, the main structures of the K edge ELNES spectra of sulfur atoms in Janus monolayers occur at lower energies, due to the structural change and increased bond length. The relative reduction of intensities in the main structures predicts the possibility of reducing the number of partial densities of states (PDOS), that is, the reduced p PDOS for the K edge in the corresponding energy range. In the K (L2,3) edge ELNES spectra of the sulfur atom in Janus monolayers and MoS2 monolayers, the main structures are due to the electron transfer to the unoccupied px+py and pz states (3s of sulfur and 4d states of the transition metal). [ABSTRACT FROM AUTHOR]

This paper reports on computational results of continuum spectra of atomic lithium in white-dwarf-strength magnetic fields. The adiabatic-basis-expansion method with R -matrix propagation has been used to study photoionization of magnetized alkali metal atoms. The R -matrix propagation technique and the two-dimensional matching scheme were utilized to obtain wavefunctions of the continuum states. Cross-sections of photoionization are calculated for lithium atoms in magnetic fields. Continuum spectra for its various bound-free transitions in magnetic white dwarf stars are presented as a function of field strengths ranging from 11.75 to 117.50 MG. Comparison is made between continuum spectra of diamagnetic hydrogen and lithium atoms. The comparison shows good agreement or remarkable difference for final continuum states with different symmetries in the photoionization processes concerned. A detailed analysis has been performed to understand the obtained results. The good agreement displayed manifests the reliability of the extended adiabatic-basis-expansion method. This method is suited to produce a large number of photoionization cross-section data for alkali metal atoms in a strong magnetic field, and therefore can serve as a tool to simulate continuum spectra observed in the atmospheres of magnetic white dwarfs with alkali metal atoms. [ABSTRACT FROM AUTHOR]

Electron Beam Ion Traps (EBITs) serve as efficient tools for producing and studying highly charged ions. In response to the diagnostic requirements of upcoming magnetic confinement fusion devices, a medium-energy atomic spectra research platform based on a compact EBIT is developed. This platform achieves a central magnetic field of up to 1.0 T, with electron beam currents reaching 20 mA and electron energies up to 30 keV, similar to the electron temperature on fusion reactors. The developed atomic spectra platform successfully provided spectral data for elements such as argon, xenon, iron, and tungsten. This platform stands as a valuable asset for advancing research in nuclear fusion, particularly concerning impurity spectroscopic diagnostics. [ABSTRACT FROM AUTHOR]

Context. Understanding the physical conditions of circumstellar material around young stars is crucial to star and planet formation studies. In particular, very low-mass stars (M★ < 0.2 M⊙) are interesting sources to characterize as they are known to host a diverse population of rocky planets. Molecular and atomic hydrogen lines can probe the properties of the circumstellar gas. Aims. This work aims to measure the mass accretion rate, the accretion luminosity, and more generally the physical conditions of the warm emitting gas in the inner disk of the very low-mass star 2MASS-J16053215-1933159. We investigate the source mid-infrared spectrum for atomic and molecular hydrogen line emission. Methods. We present the full James Webb Space Telescope (JWST) Mid-InfraRed Instrument (MIRI) Medium Resolution Spectrometer (MRS) spectrum of the protoplanetary disk around the very low-mass star 2MASS-J16053215-1933159 from the MINDS GTO program, previously shown to be abundant in hydrocarbon molecules. We analyzed the atomic and molecular hydrogen lines in this source by fitting one or multiple Gaussian profiles. We then built a rotational diagram for the H2 lines to constrain the rotational temperature and column density of the gas. Finally, we compared the observed atomic line fluxes to predictions from two standard emission models. Results. We identify five molecular hydrogen pure rotational lines and 16 atomic hydrogen recombination lines in the 5–20 µm spectral range. The spectrum indicates optically thin emission for both species. We use the molecular hydrogen lines to constrain the mass and temperature of the warm emitting gas. We derive a total gas mass of only 2.3 × 10−5 MJup and a temperature of 635 K for the warm H2 gas component located in the very inner disk (r < 0.033 au), which only accounts for a small fraction of the upper limit for the disk mass from continuum observations (0.2 MJup). The HI (7−6) recombination line is used to measure the mass accretion rate (4.0 × 10−10M⊙ yr−1) and luminosity (3.1 × 10−3L⊙) onto the central source. This line falls close to the HI (11−8) line, however at the spectral resolution of JWST MIRI we managed to measure both separately. Previous studies based on Spitzer have measured the combined flux of both lines to measure accretion rates. HI recombination lines can also be used to derive the physical properties of the gas using atomic recombination models. The model predictions of the atomic line relative intensities constrain the atomic hydrogen density to about 109−1010 cm−3 and temperatures up to 5000 K. Conclusions. The JWST-MIRI MRS observations for the very low-mass star 2MASS-J16053215-1933159 reveal a large number of emission lines, many originating from atomic and molecular hydrogen because we are able to look into the disk warm molecular layer. Their analysis constrains the physical properties of the emitting gas and showcases the potential of JWST to deepen our understanding of the physical and chemical structure of protoplanetary disks. [ABSTRACT FROM AUTHOR]

Physical principles and modern techniques for the formation of spontaneous vacuum ultraviolet radiation are described for three cases: the formation of line spectra of atoms, line spectra of multicharged ions and continuous spectra of excimer molecules. The parameters of the radiation sources are correlated with their applications: real and potential. The following schemes of the formation of vacuum ultraviolet radiation are described: H-type and E-type high frequencies discharges; discharge in a hollow cathode; glow, barrier, and arc discharges; high-voltage nanosecond discharge with a sharply inhomogeneous distribution of electric field strength in a gap; laser, discharge, and hybrid systems for multicharged ions formation; excitation of gas targets under conditions of gyrotron plasma heating. The review covers the state of the art over the last 20 years. [ABSTRACT FROM AUTHOR]

The emission spectrum of micron-scale uranium particulates at high temperatures in the ultraviolet, visible, and near-infrared spectral regions is investigated using a heterogeneous shock tube. Temperatures from 3000 to 9000 K are characterized in an inert argon environment and with incremental amounts of added oxygen. Atomic line spectra do not emerge above the continuum emission spectrum until between 4500 and 5000 K in pure argon, and 6100 and 6600 K in 1% oxygen. For 5% oxygen, however, the threshold for atomic emission drops below 3800 K. Uranium monoxide molecular emission in the strongest visible band at 595.4 nm is not observed at any condition. Uncertainties in particle temperature determination in high-temperature shock tube environments are discussed, and limitations to such measurements are presented, such as those from experimental factors such as the powder loading method and expected detection limits of uranium species in relevant conditions. [ABSTRACT FROM AUTHOR]

Compact and robust structures to precisely control and acquire atomic spectra are increasingly important for the pursuit of widespread applications. Sub‐Doppler responses of thermal atoms are critical in constructing high‐precision devices and systems. In this study, a nanograting metasurface specifically is designed for atomic rubidium vapor and integrated it into a miniature vapor cell. Using the metasurface with built‐in multifunctional controls for light, pump‐probe atomic spectroscopy is established and sub‐Doppler responses are experimentally observed at low incident power. Moreover, the sub‐Doppler lineshape can be tailored by varying the incident polarization state. The spectrum transformation from absorption to transparency is observed. Using one of the sharp responses, laser stabilization with a stability of 3×10−10$3\times 10^{-10}$ at 2 s can be achieved. This work reveals the effective control of atomic spectra with optical metasurface chips, which may have great potential for future developments in fundamental optics and novel optical applications. [ABSTRACT FROM AUTHOR]

The linear radical cation of cyanoacetylene, HC3N+ (2Π), is not only of astrophysical interest, being the, so far undetected, cationic counterpart of the abundant cyanoaceteylene, but also of fundamental spectroscopic interest due to its strong spin–orbit and Renner–Teller interactions. Here, we present the first broadband vibrational action spectroscopic investigation of this ion through the infrared pre-dissociation (IRPD) method using a Ne tag. Experiments have been performed using the FELion cryogenic ion-trap instrument in combination with the FELIX free-electron lasers and a Laservision optical parametric oscillator/optical parametric amplifier system. The vibronic splitting patterns of the three interacting bending modes (ν5, ν6, ν7), ranging from 180 to 1600 cm−1, could be fully resolved revealing several bands that were previously unobserved. The associated Renner–Teller and intermode coupling constants have been determined by fitting an effective Hamiltonian to the experimental data, and the obtained spectroscopic constants are in reasonable agreement with previous photoelectron spectroscopy (PES) studies and ab initio calculations on the HC3N+ ion. The influence of the attached Ne atom on the infrared spectrum has been investigated by ab initio calculations at the RCCSD(T)-F12a level of theory, which strongly indicates that the discrepancies between the IRPD and PES data are a result of the effects of the Ne attachment. [ABSTRACT FROM AUTHOR]

The linear radical cation of cyanoacetylene, HC3N+ (2Π), is not only of astrophysical interest, being the, so far undetected, cationic counterpart of the abundant cyanoaceteylene, but also of fundamental spectroscopic interest due to its strong spin–orbit and Renner–Teller interactions. Here, we present the first broadband vibrational action spectroscopic investigation of this ion through the infrared pre-dissociation (IRPD) method using a Ne tag. Experiments have been performed using the FELion cryogenic ion-trap instrument in combination with the FELIX free-electron lasers and a Laservision optical parametric oscillator/optical parametric amplifier system. The vibronic splitting patterns of the three interacting bending modes (ν5, ν6, ν7), ranging from 180 to 1600 cm−1, could be fully resolved revealing several bands that were previously unobserved. The associated Renner–Teller and intermode coupling constants have been determined by fitting an effective Hamiltonian to the experimental data, and the obtained spectroscopic constants are in reasonable agreement with previous photoelectron spectroscopy (PES) studies and ab initio calculations on the HC3N+ ion. The influence of the attached Ne atom on the infrared spectrum has been investigated by ab initio calculations at the RCCSD(T)-F12a level of theory, which strongly indicates that the discrepancies between the IRPD and PES data are a result of the effects of the Ne attachment. [ABSTRACT FROM AUTHOR]

Fluorine, depending on its concentration and chemical form, is essential or toxic to humans and animals. Therefore, it is crucial to be able to determine it reliably. In this study, fluorine was determined in animal feed after extraction with HCl (gastric juice simulation). The standard potentiometric method with a fluoride-selective electrode (ISE) and newly developed high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GFMAS) method was applied. Feed samples turned out to be a challenge for HR-CS GFMAS. Chemical interferences (formation of competing molecules, CaF, GaCl, and GaP, instead of the target GaF molecule) and spectral effects (including a phosphorous molecule spectrum and atomic lines) were identified. An additional difficulty was caused by reagent contamination with F and memory effects. Difficulties were eliminated/reduced. The quality of ISE analysis was multi-directionally verified (including comprehensive proficiency testing). A risk of inaccuracy at low F concentration, where the calibration relationship is nonlinear, was investigated. The results of both methods were consistent, which confirms the accuracy of the methods and informs that the extracted fluorine is in fluoride form. The results of extensive ISE tests conducted in Poland in 2021–2023 have shown that, in most cases, the fluoride content is significantly lower than the threshold values. [ABSTRACT FROM AUTHOR]

The present study describes the potential use of the Laser-induced breakdown spectroscopy (LIBS) coupled with the principle component analysis (PCA) for the discrimination/analysis of the precious gold alloy has been reported. It is very hard to discriminate between the Au-Alloys using conventional LIBS and it has been suggested that the use of multivariate methods assisted LIBS could solve the problem. Gold alloys of karats 18 K, 19 K, 20 K, 22 K, and 24 K with concentrations of 75, 79, 85, 93, and 99.9% have been tested and analyzed using LIBS. Plasma was generated on the surface of the target sample by focusing Nd: YAG laser under atmospheric pressure. Time-integrated emission spectra from plasma were collected in the range of 250–870 nm. The characteristic emission lines of constituents were identified using the NIST atomic spectra database. Normalized optical emission intensities of the detected elements were used as input data for principle component analysis (PCA). Five different three-dimensional clusters were observed, that belonged to five different karats of gold, suggesting the reliability of the model for the classification of precious alloy samples. The finding from this study showed that the LIBS coupled with PCA is an effective method for the classification of gold alloys with different percentages. [ABSTRACT FROM AUTHOR]

We studied the electron spin resonance (ESR) spectra of nitrogen atoms stabilized in nitrogen-neon nanoclusters immersed in superfluid 4 He. The nanoclusters were formed during the condensation of the products of the discharge in N 2 –Ne–He gas mixtures into bulk superfluid 4 He at temperature 1.5 K. We studied nanoclusters formed by injection of gas mixtures with different ratios of heavy impurities in the helium N 2 /(Ne + N 2 ) ranging from 2% to 90%. Analysis of the ESR spectra of nitrogen atoms stabilized in nitrogen-neon nanoclusters provides important information about the environment of the stabilized atoms and a shell structure of the nanoclusters was revealed. For all samples studied, preferential stabilization of N atoms on the surfaces of the nanoclusters was observed. Annealing of the collection of the nanoclusters in the temperature range 1.1–10 K resulted in substantial changes in the structure of the nanoclusters. [ABSTRACT FROM AUTHOR]

• Nanoparticles hygroscopic hydrolysis was analyzed by SPRM-ARI. • The volatility effect on hygroscopicity of acetate aerosol was understood. • The growth factors of acetate aerosols were determined after cyclic humidification. • The addition of organic component can inhibit volatility of multicomponent aerosol. Under high relative humidity (RH) conditions, the release of volatile components (such as acetate) has a significant impact on the aerosol hygroscopicity. In this work, one surface plasmon resonance microscopy (SPRM) measurement system was introduced to determine the hygroscopic growth factors (GFs) of three acetate aerosols separately or mixed with glucose at different RHs. For Ca(CH 3 COO) 2 or Mg(CH 3 COO) 2 aerosols, the hygroscopic growth trend of each time was lower than that of the previous time in three cyclic humidification from 70% RH to 90% RH, which may be due to the volatility of acetic acid leading to the formation of insoluble hydroxide (Ca(OH) 2 or Mg(OH) 2) under high RH conditions. Then the third calculated GF (using the Zdanovskii-Stokes-Robinson method) for Ca(CH 3 COO) 2 or Mg(CH 3 COO) 2 in bicomponent aerosols with 1:1 mass ratio were 3.20% or 5.33% lower than that of the first calculated GF at 90% RH. The calculated results also showed that the hygroscopicity change of bicomponent aerosol was negatively correlated with glucose content, especially when the mass ratio of Mg(CH 3 COO) 2 to glucose was 1:2, the GF at 90% RH only decreased by 4.67% after three cyclic humidification. Inductively coupled plasma atomic emission spectrum (ICP-AES) based measurements also indicated that the changes of Mg2+concentration in bicomponent was lower than that of the single-component. The results of this study reveal thatduring the efflorescence transitions of atmospheric nanoparticles, the organic acids diffusion rate may be inhibited by the coating effect of neutral organic components, and the particles aging cycle will be prolonged. [Display omitted] [ABSTRACT FROM AUTHOR]

We report on a combined experimental and theoretical study of stoichiometric Heusler-structure Ni2MnSn. Our detected Mössbauer spectrum of Sn atoms can be fitted as a combination of four components. As only a single component is expected in the defect-free Ni2MnSn, we have performed quantum-mechanical calculations of Ni2MnSn with selected point defects, in particular, all three fundamental types of swaps (Mn–Ni, Mn–Sn and Ni–Sn). Our phonon and elasticity calculations indicate that the swaps result in (i) magnitudes of local magnetic moments of Sn atoms within four ranges of values and (ii) mean square displacements of Sn atoms falling within four intervals of values. Further, we used calculations of phonons and elastic properties to assess mechanical, dynamical and thermodynamic stability of swap-containing states. Our results indicate that a majority of the studied swaps is reducing the stability of Ni2MnSn and need to be stabilized by the surrounding matrix. [ABSTRACT FROM AUTHOR]

The influence of scavengers of the primary water radiolysis products and the H atom on the spectra and intensity of radioluminescence and photoluminescence of the Tb3+ ion in aqueous solutions of TbCl3 and Tb(NO3)3 is considered. The effect of activation of Tb3+ radioluminescence in the presence of H scavengers has been revealed, indicating the presence of a specific (Tb3+)* quenching reaction by this radiolysis product, which is inhibited by its scavengers. Enhancement in the activation has been revealed in the joint presence of H and scavengers in the solution, with a similar effect of activation of Tb3+ radioluminescence being previously established for scavengers. [ABSTRACT FROM AUTHOR]

We construct a new modification of correlation consistent effective core potentials (ccECPs) for late 3d elements Cr–Zn with Ne-core that are adapted for efficiency and low energy cut-offs in plane wave calculations. The decrease in accuracy is rather minor, so that the constructions are in the same overall accuracy class as the original ccECPs. The resulting new constructions work with energy cut-offs at or below ≈400 Ry and, thus, make calculations of large systems with transition metals feasible for plane wave codes. We also provide the basic benchmarks for atomic spectra and molecular tests of this modified option that we denote as ccECP-soft. [ABSTRACT FROM AUTHOR]

We introduce new correlation consistent effective core potentials (ccECPs) for the elements I, Te, Bi, Ag, Au, Pd, Ir, Mo, and W with 4d, 5d, 6s, and 6p valence spaces. These ccECPs are given as a sum of spin-orbit averaged relativistic effective potential (AREP) and effective spin–orbit (SO) terms. The construction involves several steps with increasing refinements from more simple to fully correlated methods. The optimizations are carried out with objective functions that include weighted many-body atomic spectra, norm-conservation criteria, and SO splittings. Transferability tests involve molecular binding curves of corresponding hydride and oxide dimers. The constructed ccECPs are systematically better and in a few cases on par with previous effective core potential (ECP) tables on all tested criteria and provide a significant increase in accuracy for valence-only calculations with these elements. Our study confirms the importance of the AREP part in determining the overall quality of the ECP even in the presence of sizable spin–orbit effects. The subsequent quantum Monte Carlo calculations point out the importance of accurate trial wave functions that, in some cases (mid-series transition elements), require treatment well beyond a single-reference. [ABSTRACT FROM AUTHOR]

We report high‐quality solid‐state 35/37Cl NMR spectra for chlorine atoms directly bonded to paramagnetic cobalt(II) ions (high spin S = 3/2) in powered samples of CoCl2, CoCl2·2H2O, CoCl2·6H2O, and CoCl2(terpy) (terpy = 2,2′:6′,2″‐terpyridine). Because solid‐state 35/37Cl NMR spectra for paramagnetic cobalt(II) compounds often cover an extremely wide spectral range, they were recorded in this work in the form of variable‐offset cumulative spectra. Solid‐state 35/37Cl NMR measurements were performed at three magnetic fields (11.7, 14.1, and 16.5 T) and analysis of data yielded information about 35/37Cl quadrupole coupling and hyperfine coupling tensors in these paramagnetic cobalt(II) compounds. Experimental 35/37Cl NMR tensors were found to be in reasonable agreement with quantum chemical calculations based on a periodic DFT method implemented in BAND. [ABSTRACT FROM AUTHOR]

Previously reported atomic data (spectral lines, wavelengths, energy levels, and transition probabilities) were collected and systematically analyzed for Cs VI. The present theoretical analysis was supported by extensive calculations made for Cs VI with a pseudo-relativistic Hartree–Fock (HFR) method together with the superposition of configuration interactions implemented in Cowan's codes. In this work, all previously reported energy levels and their (allowed) transition assignments were confirmed. A critically evaluated set of optimized energy levels with their uncertainties, observed and Ritz wavelengths along with their uncertainties, and theoretical transition probabilities with their estimated uncertainties were presented in the compilation. In addition to this, we determined the radiative transition parameters for several forbidden lines within the ground configuration 5 s 2 5 p 2 of Cs VI. [ABSTRACT FROM AUTHOR]

Atoms and ions remain in some long-lived excited levels for much longer than in typical "normal" levels, but not forever. Various cases of this so-called metastability that occur in multiply or even highly charged ions are discussed in a tutorial review, as well as examples of atomic lifetime measurements on such levels, their intentions, and some present and future applications. [ABSTRACT FROM AUTHOR]

When investigating complex atomic spectra, it may happen accidentally that two or even several transitions between different pairs of combining energy levels have nearly the same wavenumber, and the observed spectral lines are overlapping (blend situations). In such cases, investigations of hyperfine structures can be very helpful in the identification of the involved transitions. In this paper, two complicated blend situations within the spectra of lanthanide atoms (Praseodymium and Lanthanum) are discussed as examples. The experimental methods applied are optogalvanic and laser-induced fluorescence spectroscopy, combined with emission spectra gained via Fourier transform spectroscopy. It is shown that, in such cases, a combination of optogalvanic and laser-induced fluorescence detection is necessary to find all transitions contributing to the observed spectral signatures. [ABSTRACT FROM AUTHOR]

Developing highly efficient and stable electrocatalysts with large current densities for hydrogen and oxygen evolution is still challenging. Herein, Ni and Fe co‐doped cobalt carbonate hydroxide catalysts were designed in situ on the three‐dimensional porous NiFe foam through a facile one‐step hydrothermal strategy. Inductively coupled plasma atomic emission spectrum, transmission electron microscopy‐element mapping, X‐ray photoelectron spectroscopy, and DFT calculations demonstrate that the three‐dimensional NiFe foam substrate not only serves as the porous substrate, which enhances the exposed number of active sites, but also enhances the intrinsic activities of single active sites via introducing Ni and Fe dopants in the cobalt carbonate hydroxide catalyst during the hydrothermal process. The obtained hybrid electrocatalyst can be employed as a highly efficient and stable bifunctional electrocatalyst for the oxygen and hydrogen evolution reactions, with overpotentials of 340 mV and 371 mV at 1000 mA cm−2, respectively. In addition, tests in an alkaline electrolyzer revealed that the current density could reach 1000 mA cm−2 at a voltage of 2 V and maintain stable operation for 100 h. [ABSTRACT FROM AUTHOR]

We investigate effects of a classical external field and the initial state of the field on the nonlinear interaction of a Λ-type three-level atom with the two-mode field through the Raman type interaction. Appropriate canonical transforms are performed for atomic states. The analytic solution to the model is obtained, using the Schrödinger differential equation. The wave function is obtained under specific initial conditions of the atom and field. The effect of a classical external field and the initial state of the field on the population occupations, the squeezing phenomenon, and the atomic emission spectrum are studied. The collapse–revival phenomena are affected by the presence of the classical field. Increasing the activation of the role of the initial state of the field improves the phenomena of collapses and revivals. The squeezing intervals decrease with increase in the classical field effect. The squeezing intervals increase with decrease of the parameter of the initial state of the field. The maximum values of the emission spectrum are improved after taking into account the classical field. In addition, the peaks significantly decrease after reducing the influence of both the bandwidth of the filter and the interaction time. [ABSTRACT FROM AUTHOR]

High-resolution optical multidimensional coherent spectroscopy (MDCS) requires frequency-stable laser sources and high-resolution heterodyne spectra. Fully phase-locked dual-comb spectroscopy (DCS) enables the achievement of high resolution, high accuracy, broad bandwidth, and a rapid multi-heterodyne spectrum, which results in the DCS's potential to replace the spectrometer and phase detection system in MDCS. We verified the phase measurement capability of the MDCS system based on fully phase-locked fiber DCS by studying phase-sensitive photon echoes and double-quantum processes. The accurate phase and frequency of linear and nonlinear signals were obtained simultaneously using a single detector without subsequent frequency drift correction. Subsequently, the acquisition of longtime quantum beat signals demonstrates the high phase coherence between excitation pulses. Additionally, the two-dimensional coherent spectrum (2DCS) with high signal-to-noise-ratio and 100 MHz resolution was obtained via the MDCS system based on fully phase-locked fiber DCS. These results exhibit that fully phase-locked fiber DCS is an effective method for high-resolution 2DCS measurement, which facilitates further research on cold atoms, higher-order nonlinear spectra, and molecular fingerprint vibrational spectroscopy. [ABSTRACT FROM AUTHOR]

The problem of descent spacecrafts safety is closely related to the correct assessment of heat fluxes to their surface. This work is devoted to an experimental study of radiative heat fluxes that play an important role during the entry of a spacecraft into the Earth's atmosphere at superorbital velocity. The radiation properties of high-temperature air were measured in the detonation driven shock tube DDST-M at the gas pressure 0.25 Torr ahead of the shock wave in the shock wave velocity range from 7.7 to 11.4 km/s. The applied registration method fixates the time-integrated distribution of the radiation intensity of the shock heated air passing by the measuring cross section. The measurements were carried out in the spectral range from 190 to 1100 nm. Simultaneously, the evolution of the radiation power at certain wavelengths that are selected using monochromators was recorded. Time spectrograms at certain wave lengths make it possible to determine the effective process time that can be used to recalculate the measured integral radiation intensity to the radiation power that traditionally measures by 3-D spectroscopy method. A new spectral model is presented that performs a line-by-line calculation of the emission and absorption spectra of atoms and molecules. The experimental results are compared with the calculated data obtained using the spectral model, as well as data from other measurements. • Heat fluxes to spacecrafts surface. • New experimental data on the radiation of shock-heated air in in the spectral range from 190 to 1100 nm. • A new spectral model that performs a line-by-line calculation of the emission and absorption spectra of atoms and molecules. [ABSTRACT FROM AUTHOR]

We propose ab-initio reduced rate equation models (with maximum 7 levels) to calculate the saturated absorption spectra (SAS) of thermal atomic vapor for linearly polarized pump and probe beams. We also experimentally validate our simplified models, that consume ∼ 100 × lower computational resources than full multi-level models, for all four hyperfine dips of the Rb D 2 line with residual error ≲ 3 % and no fitting parameters with various pump-probe intensities and beam diameters. Our 5-level model, which considers hyperfine pumping but ignores Zeeman pumping, accurately predicts enhanced saturated probe transmission at all the resonances and crossovers. However, this model is unable to predict reduced probe transmission induced by the Zeeman ( m F ) sub-level pumping at the crossover X 10 , comprising hyperfine transitions F g = 1 → F e = 0 and F e = 1 of 87 Rb. In this case, our 7-level model, which accounts for both hyperfine and Zeeman pumping, faithfully reproduces all the SAS features corresponding to the hyperfine transitions F g = 1 → F e = 0 , 1 , 2 of 87 Rb. In addition, both our models account for the transit-relaxation (depending on beam diameter) of atoms traversing the laser beam for an accurate computation. Finally, we also present theoretical and experimental evidence demonstrating the significance of probe-induced hyperfine pumping even at intensities ∼ 10 × smaller than that required for two-level saturation. [ABSTRACT FROM AUTHOR]

We explore the merits of linear-response range-separated time-dependent density-functional theory (TDDFT) for the calculation of photoionization spectra. We consider two variants of range-separated TDDFT, namely, the time-dependent range-separated hybrid (TDRSH) scheme, which uses a global range-separation parameter, and the time-dependent locally range-separated hybrid (TDLRSH), which uses a local range-separation parameter, and compare with standard time-dependent local-density approximation (TDLDA) and time-dependent Hartree–Fock (TDHF). We show how to calculate photoionization spectra with these methods using the Sternheimer approach formulated in a non-orthogonal B-spline basis set with appropriate frequency-dependent boundary conditions. We illustrate these methods on the photoionization spectrum of the Be atom, focusing, in particular, on the core resonances. Both the TDRSH and TDLRSH photoionization spectra are found to constitute a large improvement over the TDLDA photoionization spectrum and a more modest improvement over the TDHF photoionization spectrum. [ABSTRACT FROM AUTHOR]

This document discusses the use of spectroscopy in the characterization of materials. Spectroscopy is the study of the interaction of light with matter, and it has been expanded to include various techniques such as absorption spectroscopy, fluorescence spectroscopy, and infrared spectroscopy. Over time, spectroscopy has undergone significant development, with advancements in instrumentation, methodology, and theoretical understanding. Recent trends in spectroscopic techniques include terahertz spectroscopy, single-molecule spectroscopy, plasmonic nanospectroscopy, and quantum spectroscopy. These techniques have applications in fields such as biology, medicine, environmental monitoring, and materials science. The document emphasizes the dynamic nature of spectroscopy as it continues to adapt and advance to meet the demands of diverse fields. [Extracted from the article]

A pair of enantiomeric photoswitchable PdII catalysts, alkyne‐PdII/LR−azo and alkyne‐PdII/LS−azo, were prepared via the coordination of alkyne‐PdII and azobenzene‐modified phosphine ligands LR−azo and LS−azo. Owing to the cis‐trans photoisomerization of the azobenzene moiety, alkyne‐PdII/LR−azo and alkyne‐PdII/LS−azo exhibited different polymerization activities, helix‐sense selectivities, and enantioselectivities during the polymerization of isocyanide monomers under irradiation of different wavelength lights. Furthermore, the achiral isocyanide monomer A‐1 could be polymerized efficiently using alkyne‐PdII/LR−azo under dark condition in a living/controlled manner. Further, it generated single right‐handed helical poly‐A‐1m(LR−azo), confirmed by the circular dichroism spectra and atomic force microscopy images. However, the polymerization of A‐1 almost could not be initiated under 420 nm light in identical conditions of dark condition. Moreover, the photoswitchable catalyst alkyne‐PdII/LR−azo exhibited high enantioselectivity for the polymerization of the racemates of L‐1 and D‐1, respectively. D‐1 was polymerized preferentially under dark condition with a D‐1/L‐1 rate ratio of 70, yielding single right‐handed polyisocyanides. Additionally, reversible enantioselectivity was observed under 420 nm light using alkyne‐PdII/LR−azo, and the calculated polymerization rate ratio of L‐1/D‐1 was 57 because of the isomerization of the azobenzene moiety of the catalyst. Furthermore, alkyne‐PdII/LS−azo showed opposite enantioselectivity and helix‐sense selectivity during the polymerization of the racemates of L‐1 and D‐1. [ABSTRACT FROM AUTHOR]

For upcoming experiments, we require a linear magnetic field to be applied over the longitudinal extent of an atom's trajectory through a vertically oriented atom interferometer. Additionally, we plan to use magnetically sensitive states. This combination comes at the cost of increased sensitivity to noise in the external field environment and, as a result, the magnetic field must be more carefully characterized and controlled than in a standard atom interferometer. We present our methods to characterize an extended, linear magnetic field environment which can be suitable for making such a system. We perform standard Raman spectroscopy but by adding time resolution to the spectroscopy, we are able to use the expansion of a thermal cloud of atoms to sample a large range along the ballistic atom path with a single spectrum. A small number of these spectra can then be used to map the field along the entire path with better precision than standard Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Absorbed power of the neutral-injection beam in spherical tokamaks Globus-M/M2 is estimated numerically. Deceleration of fast particles is simulated by means of the NUBEAM code. The signal of analyzer of charge-exchange atoms is simulated by means of the FIDASIM code using the distribution function of fast ions calculated by means of the NUBEAM code. Comparison of calculated and experimental signals allowed determining the degree of influence of instabilities on confinement of fast particles along with absorbed beam power. [ABSTRACT FROM AUTHOR]

La2O3 nanoparticles stabilized on carbon nanoflake (CNF) matrix were synthesized and graphitized to produce core-shell structures La2O3/CNFs@C. Further oxidation of these structures by nitric acid vapors for 1, 3 or 6 h was performed, and surface-oxidized particles La2O3/CNFs@C_x (x = 1, 3, 6) were produced. Bulk and surface compositions of La2O3/CNFs@C and La2O3/CNFs@C_x were investigated by thermogravimetric analysis and X-ray photoelectron spectroscopy. With increasing the duration of oxidation, the oxygen and La2O3 content in the La2O3/CNFs@C_x samples increased. The electronic structures of samples were assessed by electron paramagnetic resonance. Two paramagnetic centers were associated with unpaired localized and mobile electrons and were registered in all samples. The correlation between bulk and surface compositions of the samples and their electronic structures was investigated for the first time. The impact of the ratio between sp2- and sp3-hybridized C atoms, the number and nature of oxygen-containing groups on the surface and the presence and proportion of coordinated La atoms on the EPR spectra was demonstrated. [ABSTRACT FROM AUTHOR]

The present study aims to introduce a new catalytic system, namely, thermo-responsive amphiphilic manganese porphyrin-paired ionic co-polymeric hydrogel, poly(N-isopropylacrylamide-co-2-acrylamido-2-methylpropane sulfonic acid sodium)-Mn(III) meso tetra(N-methyl-4-pyridyl) porphine, briefly called p(NIPAM-co-NaAMPS)‐[Mn(TMPyP)]. Free-radical polymerization at ambient temperature was employed to construct this catalytic system. To prepare this temperature-sensitive catalyst, "smart" poly(N-isopropylacrylamide-co-NaAMPS) was axially grafted onto the metal centers of the MnIII composite. Dynamic light scattering was used to determine the temperature-responsiveness of the catalyst and the hydrodynamic radii of the constructed compounds. In order to identify the amounts of metals in prepared compound, atomic absorption spectroscopy (AAS) was utilized. The results indicated that p(NIPAM-co-NaAMPS)‐[Mn(TMPyP)] had the potential to efficiently catalyze olefin oxidation with high selectivity in the solid–liquid biphasic reaction system. Furthermore, the catalytic activities of styrene, α-methyl-styrene, cis-cyclooctene, indene oxidation by the reaction-controlled phase transfer catalyst system were compared in the presence of hydrogen peroxide (H2O2) and tert-Butyl hydroperoxide (TBHP), as oxidants, in a biphasic environment. It was found that functioning as a nanoreactor, the prepared catalyst system facilitated the epoxidation of un-functionalized olefins in water, leading to the substantial acceleration of catalytic reaction rates. After the completion of the catalytic activity, the catalyst could be separated easily from the reaction media by manipulating temperature and reused without any activity loss. In effect, the quality of the catalyst remained the same for eight cycles. In a similar vein, the FT-IR spectra and atomic absorption spectroscopy confirmed the great recyclability, durability, and leaching resistance of the catalyst. The present study aims to introduce a new catalytic system, namely, thermo-responsive amphiphilic manganese porphyrin-paired ionic co-polymeric hydrogel, poly(N-isopropylacrylamide-co-2-acrylamido-2-methylpropane sulfonic acid sodium)-Mn(III) meso tetra(N-methyl-4-pyridyl) porphine, briefly called P(NIPAM-co-NaAMPS)‐[Mn(TMPyP)]. [ABSTRACT FROM AUTHOR]

The variations of exchange Slater integrals with respect to their order k are not well known. While direct Slater integrals Fk are positive and decreasing when the order increases, this is not stricto sensu the case for exchange integrals Gk. However, two inequalities were published by Racah in his seminal article 'Theory of complex spectra. II'. In this article, we show that the technique used by Racah can be generalized, albeit with cumbersome calculations, to derive further relations, and provide two of them, involving respectively three and four exchange integrals. Such relations can prove useful to detect regularities in complex atomic spectra and classify energy levels. [ABSTRACT FROM AUTHOR]

The integral and temporal spectral characteristics of shock-heated air are measured in the shock wave velocity range from 7.35 to 10.4 km/s at the pressure ahead of the shock front p0 = 0.25 Torr. The experiments are carried out on the DDST-M shock-wave setup of the Institute of Mechanics of Moscow State University. The radiation wave range λ = 600–1100 nm is studied; it corresponds to the visible and near infrared spectral ranges, where the main contribution to the radiation is made by the atomic lines of nitrogen and oxygen. The integral-in-time radiation spectrograms obtained in the experiments are analyzed. The distinctive features of the time oscillograms are defined for the most typical atomic lines of the spectrum. The measurement data are compared with the experimental data of other authors. [ABSTRACT FROM AUTHOR]

The hyperfine structure of the components of the doublet EPR spectrum of atomic hydrogen in silicon dioxide (silica gel, quartz, or molybdenum glass) γ-irradiated at 77 K is due to the overlap of two doublets with α = 50.5 and 50.4 mT, a standard singlet and a resolved multiplet, responsible for the accumulation and stabilization of two types of surface and bulk atomic hydrogen. Surface hydrogen atoms formed upon the dissociation of surface OH groups and water molecules are stabilized in dry traps, and they have a standard doublet with α = 50.5 mT in the EPR spectra. Bulk hydrogen atoms are formed (upon radiolysis) and stabilized in internal water clusters of SiO2. In the water medium of clusters, bulk hydrogen atoms are affected by the protons of the water environment and, interacting with protons, they exhibit a multiplet doublet with α = 50.4 mT in the EPR spectra. The contribution of the multiplet doublet to the total spectrum depends on the type of SiO2 and the radiation dose. The fraction of a multiplet doublet in macroporous glass at a dose of 120 kGy was 40%. When water was completely removed from a SiO2 matrix, bulk hydrogen atoms disappeared, and a standard doublet of atomic hydrogen was recorded in the EPR spectra after an irradiation dose of 40 kGy or higher. [ABSTRACT FROM AUTHOR]

Key issues in AGN and galaxy formation are discussed. Very successful Unified Models explain much of the variety of AGN with orientation effects; the ingredients are shadowing by a dusty "torus" and relativistic beaming. A spinoff result is described which is important for the formation of massive elliptical galaxies, the most spectacular and unequivocal AGN feedback phenomenon known. This is the so-called "alignment effect" in powerful radio galaxies at z ≳ 1. One of them is a BAL radio galaxy! Next, I explain a very robust derivation of the reddening law for nuclear dust, which reveals a dearth of small grains on parsec scales. Then, the quasistatic thin accretion disk model, thought by many to explain the energetically dominant optical/UV continuum, is thoroughly debunked. Much of this was known when the model was proposed 35 years ago. A new argument is provided that trivially falsifies a huge superset of such models. I then show that it is possible to see the central engine spectrum with the atomic and dust emission surgically removed! Few have noticed this breakthrough work. Finally, the far IR dust emission in Cygnus A is 10% polarized; to date, high nuclear dust polarization has been seen in all radio loud objects and no radio quiet ones. [ABSTRACT FROM AUTHOR]

We present the time-independent (TI) and time-dependent (TD) equation of motion coupled-cluster (EOM-CC) oscillator strengths not limited to those obtained by the dipole approximation. For the conventional TI-EOM-CC, we implement all the terms in the multipole expansion through second order that contributes to the oscillator strength. These include contributions such as magnetic dipole, electric quadrupole, electric octupole, and magnetic quadrupole. In TD-EOM-CC, we only include the quadrupole moment contributions. This augments our previous work [Y. C. Park, A. Perera, and R. J. Bartlett, J. Chem. Phys. 151, 164117 (2019)]. The inclusion of the quadrupole contributions (and all the other contributions through second order in the case of TI-EOM-CCSD) enables us to obtain the intensities for the pre-edge transitions in the metal K-edge spectra, which are dipole inactive. The TI-EOM-CCSD and TD-EOM-CCSD spectra of Ti4+ atoms are used to showcase the implementation of the second-order oscillator strengths. The origin of 1s → e and 1s → t2 in core spectra from iron tetrachloride and titanium tetrachloride is discussed and compared with the experiment. [ABSTRACT FROM AUTHOR]

We devise an efficient scheme to determine vibrational properties from Path Integral Molecular Dynamics (PIMD) simulations. The method is based on zero-time Kubo-transformed correlation functions and captures the anharmonicity of the potential due to both temperature and quantum effects. Using analytical derivations and numerical calculations on toy-model potentials, we show that two different estimators built upon PIMD correlation functions fully characterize the phonon spectra and the anharmonicity strength. The first estimator is associated with the force–force quantum correlators and, in the weak anharmonic regime, yields reliable zero-point motion frequencies and thermodynamic properties of the quantum system. The second one is instead connected to displacement–displacement correlators and accurately probes the lowest-energy phonon excitations, regardless of the anharmonicity strength of the system. We also prove that the use of generalized eigenvalue equations, in place of the standard normal mode equations, leads to a significant speed-up in the PIMD phonon calculations, both in terms of faster convergence rate and smaller time step bias. Within this framework, using ab initio PIMD simulations, we compute phonon dispersions of diamond and of the high-pressure I41/amd phase of atomic hydrogen. We find that in the latter case, the anharmonicity is stronger than previously estimated and yields a sizeable red-shift in the vibrational spectrum of atomic hydrogen. [ABSTRACT FROM AUTHOR]

Measurements of the L-shell X-ray emission of fluorine-like europium ions (Eu54+) were made under controlled laboratory conditions on the EBIT-I electron beam ion trap at Livermore using an X-ray calorimeter, extending such measurements to the middle of the rare earth elements. Comparing the calorimeter spectra with atomic data from the flexible atomic code, we have identified and analyzed several prominent n = 3 → n = 2 transitions, including one two-electron, one-photon core changing transition and one electric quadrupole transition. We find that the measured energies are typically up to several eV higher than predicted. [ABSTRACT FROM AUTHOR]

The luminescence excitation spectra of the D1 resonance line of atoms K, Rb, and Cs in gas mixtures with CF4 are found to contain satellite transitions, which correspond to the transition of an atom to the states (n – 1)d2D3/2,5/2 and (n + 1)s2S1/2, where n = 4, 5, and 6 for K, Rb, and Cs, respectively, with the simultaneous excitation of CF4 molecule vibrations at the IR active mode frequency ν3 with a quantum energy of 1283 cm–1. These satellite transitions are A(ns2S1/2) + CF4(ν3 = 0) + hν → A((n – 1)d2D3/2,5/2) + CF4(ν3 = 1) and A(ns2S1/2) + CF4(ν3 = 0) + hν → A((n + 1)s2S1/2) + CF4(ν3 = 1), where A = K, Rb, and Cs. The appearance of an optical coupling between the upper and lower states of these asymptotically (at → ∞) forbidden transitions is shown to be caused by the interaction of the dipole moment of the ν3 = 1 ↔ ν3 = 0 vibrational transition in the CF4 molecule with the dipole moments of the electronic transitions np2P1/2,3/2 ↔ (n – 1)d2D3/2,5/2 and np2P1/2,3/2 ↔ (n + 1)s2S1/2 in an alkali metal atom; as a result of this interaction, the upper state of the satellite transition acquires admixtures of the A(np2P1/2,3/2)CF4(ν3 = 0) resonance states. [ABSTRACT FROM AUTHOR]

Organic semiconductors offer the opportunity to develop intrinsically stretchable skin‐like electronics for future applications. However, the lack of intrinsically stretchable materials is still a fundamental challenge, originating from the brittle nature of most organic semiconductors with the fracture strain at a few percent (<10%). Here, a stretchable semiconductor composite is reported by blending the brittle poly[4‐(4,4‐dihexadecyl‐4H‐cyclopenta[1,2‐b:5,4‐b′]dithiophen‐2‐yl)‐alt‐[1,2,5]thiad‐iazolo [3,4‐c] pyridine] (PCDTPT) semiconductor with the crack‐onset strain only at 5% and the styrene‐ethylene‐butylene‐styrene elastomer. This blend films present the increased crack‐onset strain up to 182% and superior optical transparency (>95% at 550 nm), with mobility as high as 2.31 cm2 V−1 s−1. The depth‐dependence light absorption spectra and the conductive atomic force microscopy images in horizontal and vertical directions of the blend film confirm the nonuniform distribution of PCDTPT fibers with sandwiched structure, which weakens the effect of device configuration on mobility. Compared with the conventional uniform film, the sandwiched film weakens the effect of device configuration on mobility. The fully transparent stretchable transistors with the blend films show the outstanding ductility and high optical transparency. This work opens up a feasible path for brittle organic semiconductors used in the transparent stretchable transistor, presenting their promising potential in future see‐through skin‐like electronics. [ABSTRACT FROM AUTHOR]

The luminescence excitation spectra of the D1 resonance line of atoms K, Rb, and Cs in gas mixtures with CF4 are found to contain satellite transitions, which correspond to the transition of an atom to the states (n – 1)d2D3/2,5/2 and (n + 1)s2S1/2, where n = 4, 5, and 6 for K, Rb, and Cs, respectively, with the simultaneous excitation of CF4 molecule vibrations at the IR active mode frequency ν3 with a quantum energy of 1283 cm–1. These satellite transitions are A(ns2S1/2) + CF4(ν3 = 0) + hν → A((n – 1)d2D3/2,5/2) + CF4(ν3 = 1) and A(ns2S1/2) + CF4(ν3 = 0) + hν → A((n + 1)s2S1/2) + CF4(ν3 = 1), where A = K, Rb, and Cs. The appearance of an optical coupling between the upper and lower states of these asymptotically (at → ∞) forbidden transitions is shown to be caused by the interaction of the dipole moment of the ν3 = 1 ↔ ν3 = 0 vibrational transition in the CF4 molecule with the dipole moments of the electronic transitions np2P1/2,3/2 ↔ (n – 1)d2D3/2,5/2 and np2P1/2,3/2 ↔ (n + 1)s2S1/2 in an alkali metal atom; as a result of this interaction, the upper state of the satellite transition acquires admixtures of the A(np2P1/2,3/2)CF4(ν3 = 0) resonance states. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to investigate the initial corrosion behavior of pure Mg, AZ31 and AZ91 alloys in phosphate buffer solution (PBS) and to characterize the features in corrosion type and resistance of the corrosion product layer. Design/methodology/approach: The scanning electron microscopy, equipped with energy-dispersive spectroscopy, X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy have been used to characterize the as-corroded samples. Besides, the Mg2+ concentration in PBSs has been determined by inductively coupled plasma atomic emission spectrum. Findings: It has been found that pure Mg suffers pit corrosion, and AZ31 initially undergoes pit corrosion and then uniform corrosion dominates with an extended immersion duration. However, AZ91 exhibits the uniform corrosion with the highest corrosion rate among the three materials. Besides, the corrosion product layer on AZ31 has the best compactness and corrosion resistance. Originality/value: The findings add depth in understanding the corrosion of pure Mg and its alloys in PBS and also have guiding significance in exploring the effects by alloyed elements to develop new biomaterials with better performance. [ABSTRACT FROM AUTHOR]

We present a thermal velocity sampling method for calculating Doppler-broadened atomic spectra, which more efficiently reaches convergence than regular velocity weighted sampling. The method uses equal-population sampling of the 1D thermal distribution, sampling the "inverse transform" of the cumulative distribution function, and is broadly applicable to normal distributions. We also discuss the efficiency by eliminating velocity classes, which do not significantly contribute to the observed atomic lines, and comment on the application of this method in two- and three-dimensions. [ABSTRACT FROM AUTHOR]