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Chirality-induced spin selectivity has been reported in many experiments, but a generally accepted theoretical explanation has not yet been proposed. Here, we introduce a simple model system of a straight cylindrical free-electron wire containing a helical string of atomic scattering centers with spin–orbit interaction. The advantage of this simple model is that it allows deriving analytical expressions for the spin scattering rates, such that the origin of the effect can be easily followed. We find that spin-selective scattering can be viewed as resulting from the constructive interference of partial waves scattered by the spin–orbit terms. We demonstrate that forward scattering rates are independent of spin, while back scattering is spin dependent over wide windows of energy. Although the model does not represent the full details of electron transmission through chiral molecules, it clearly reveals a mechanism that could operate in chiral systems. [ABSTRACT FROM AUTHOR]

In the field of nitride phosphors, which are crucial for phosphor‐converted light‐emitting diodes, mixed tetrahedral networks hold a significant position. With respect to the wide range of compositions, the largely unexplored (Si, P)–N networks are investigated as potential host structures. In this work, two highly condensed structures, namely Sr2SiP2N6 and Sr5Si2P6N16 are reported to address the challenges that arise from the similarities of the network‐forming cations Si4+ and P5+ in terms of charge, ionic radius, and atomic scattering factor, a multistep workflow is employed to elucidate their structure. Using single‐crystal X‐ray diffraction, energy‐dispersive X‐ray spectroscopy (EDX), atomic‐resolution scanning transmission electron microscopy (STEM)‐EDX maps, and straightforward crystallographic calculations, it is found that Sr2SiP2N6 is the first ordered, and Sr5Si2P6N16 the first disordered, anionic tetrahedral (Si, P)–N network. After doping with Eu2+, Sr2SiP2N6:Eu2+ shows narrow cyan emission (λmax = 506 nm, fwhm = 60 nm/2311 cm−1), while for Sr5Si2P6N16:Eu2+ a broad emission with three maxima at 534, 662, and 745 nm upon irradiation with ultraviolet light is observed. An assignment of Sr sites as probable positions for Eu2+ and their relation to the emission bands of Sr5Si2P6N16:Eu2+ is discussed. [ABSTRACT FROM AUTHOR]

The structural study of plant viruses is of great importance to reduce the damage caused by these agricultural pathogens and to support their biotechnological applications. Nowadays, X-ray crystallography, NMR spectroscopy and cryo-electron microscopy are well accepted methods to obtain the 3D protein structure with the best resolution. However, for large and complex supramolecular structures such as plant viruses, especially flexible filamentous ones, there are a number of technical limitations to resolving their native structure in solution. In addition, they do not allow us to obtain structural information about dynamics and interactions with physiological partners. For these purposes, small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM) are well established. In this review, we have outlined the main principles of these two methods and demonstrated their advantages for structural studies of plant viruses of different shapes with relatively high spatial resolution. In addition, we have demonstrated the ability of AFM to obtain information on the mechanical properties of the virus particles that are inaccessible to other experimental techniques. We believe that these under-appreciated approaches, especially when used in combination, are valuable tools for studying a wide variety of helical plant viruses, many of which cannot be resolved by classical structural methods. [ABSTRACT FROM AUTHOR]

An implementation of Slater‐type spherical scattering factors for X‐ray and electron diffraction for elements in the range Z = 1–103 is presented within the software Olex2. Both high‐ and low‐angle Fourier behaviour of atomic electron density and electrostatic potential can thus be addressed, in contrast to the limited flexibility of the four Gaussian plus constant descriptions which are currently the most widely used method for calculating atomic scattering factors during refinement. The implementation presented here accommodates the increasing complexity of the electronic structure of heavier elements by using complete atomic wavefunctions without any interpolation between precalculated tables or intermediate fitting functions. Atomic wavefunctions for singly charged ions are implemented and made accessible, and these show drastic changes in electron diffraction scattering factors compared with the neutral atom. A comparison between the two different spherical models of neutral atoms is presented as an example for four different kinds of X‐ray and two electron diffraction structures, and comparisons of refinement results using the existing diffraction data are discussed. A systematic but slight improvement in R values and residual densities can be observed when using the new scattering factors, and this is discussed relative to effects on the atomic displacement parameters and atomic positions, which are prominent near the heavier elements in a structure. [ABSTRACT FROM AUTHOR]

Polyoxometalates (POMs), as a unique class well‐defined metal‐oxo clusters with excellent multielectron redox properties, have attracted extensive attention in the field of energy storage and conversion, but it is still challenging to achieve their highly uniform and stable monodispersed. In this study, for the first time, polyoxovanadate (POV) is used, (NH4)2[VIV3VV3O10{NH2C(CH2O)3}3] (tris‐V6O19), as nodes and successfully obtain a 3D covalent polyoxovanadate‐organic framework through a green hydrothermal synthesis method, termed POF‐1. Total scattering atomic pair distribution function analysis confirms that POF‐1 has a noninterpenetrated diamond‐like framework, fully exposing the monodispersed tris‐V6O19, effectively utilizing the active components of VIV/VV and enhancing surface mass transfer. Notably, POF‐1 demonstrates exceptional performance in lithium‐ion batteries, achieving a high reversible capacity of 887.4 mAh g−1 at 0.1 A g−1 and retaining over 92% capacity at 1 C during 1000 cycles. Electrochemistry mechanism and density functional theory calculations reveal that V centers in tris‐V6O19 and carbonyls (C═O) in BDOEB linkers are the main active sites, with each POF‐1 fragment capable of storing up to 14 Li+. This study opens a new pathway for the efficient and green synthesis of new 3D well‐defined POM‐organic frameworks, and shows great application prospect in the field of energy storage. [ABSTRACT FROM AUTHOR]

The values of the atomic particle–solid potential were obtained for the first time from experimental data on the energy spectra and angular dependences of backscattered particles. The proposed procedure for determining the potential has never been applied previously. It is shown that the obtained data do not depend on the potential approximation used. The ion–solid interaction potential differs markedly from the potential describing collisions in the gas phase. The screening constant increases by 10–15%. The increase in screening is due to an increase in the density of the electron gas in the region between the incident particle and scattering center. [ABSTRACT FROM AUTHOR]

The single-center convergent close coupling (CCC) method has been applied to positron scattering from the oxygen atom. Cross sections have been calculated for total, elastic, momentum transfer, total ionization, inelastic, and excitation scattering processes from threshold to 5000 eV. Due to their relevance in transport studies, we also present stopping power and mean excitation energy results. Low-energy studies have been conducted to calculate scattering length, the hidden Ramsauer–Townsend minimum, and the energy of the positron virtual state. CCC-scaled complex optical potential calculations are utilized to calculate positronium-formation, direct ionization, and values between the positronium-formation and ionization thresholds. Good agreement is generally observed at high energies with past theory, electron-atomic oxygen experiment, and halved electron/positron O 2 experiment. Large discrepancies, however, have been found between current and previous calculations for positronium-formation cross section and for low-energy elastic scattering cross section. [ABSTRACT FROM AUTHOR]

Single-atom catalysts have attracted much attention because of their exceptional high activity, eminent atomic utilization, and good selectivity, exhibiting diverse performance in a wide range of energy conversion. However, with the decrease in particle size and sudden increase of surface energy, ultra-small particles may gather together to form nanoclusters and cannot maintain atomic scattering. Protecting catalytic sites requires normalizing and controlling the interaction between single atoms and substrates. Graphitic carbon-nitride, g-C 3 N 4, with a unique two-dimensional (2D) structural unit and excellent stability, exhibits a controllable electronic structure that capable to be a support for the atomically dispersed metal atoms. Mainly, g-C 3 N 4 contains many nitrogen atoms that are periodically detached and can attribute energetic positions for efficient constituents, primarily for single atoms. This review article introduced the synthetic approaches of single metal atoms (SMA) anchored g-C 3 N 4 , including synchronization atmosphere, electronic structures of SMA, and the latest characterizations towards their physiochemical applications. Solar energy conversion, including water splitting for H 2 -production and CO 2 -reduction using SMAs anchored g-C 3 N 4 , and the role of SMA in catalytic mechanism over the SMA modified g-C 3 N 4 were discussed, along with the challenges and opportunities for further research into high-efficiency SMA-modified g-C 3 N 4 photocatalysts. This review is estimated to explain the essentials and massive potential of SMAs anchored g-C 3 N 4. • This review summarized recent reports of single metal atoms (SMAs) anchored g-C 3 N 4. • The synthetic approaches and latest characterization techniques towards SMAs anchored g-C 3 N 4 were summarized. • Water splitting for hydrogen production and CO 2 reduction using SMAs anchored g-C 3 N 4 were introduced. • The prospects and remaining challenges in fields of SMAs anchored g-C 3 N 4 are supposed. [ABSTRACT FROM AUTHOR]

The use of X-ray synchrotron radiation makes it possible to observe the polarization, spectral, and angular dependences for diffraction reflections. Their theoretical study calls for application of a tensor approach to describe the interaction of X-rays with atoms of matter. Various representations of the tensor atomic scattering amplitude, results of experimental observations of the anisotropy of resonant X-ray scattering, and the relationship of the electric and magnetic multipole moments on atoms with the properties of forbidden resonant reflections are considered. [ABSTRACT FROM AUTHOR]

Approximate potentials for protons and hydrogen atoms in metals have been proposed. It has been shown that the difference between the interatomic interaction potentials obtained in the density functional theory for the gas phase and our potentials obtained by processing experimental data on the scattering of atomic particles from the surface of solids can be explained by including the screening of the charge of an incident particle. The effect of screening in the potential on the angular distributions of atomic particles passed through thin films and on nuclear stopping powers has been established. [ABSTRACT FROM AUTHOR]

We investigate the production of cold 85Rb133Cs molecules in the lowest vibronic level of the ground electronic state via the B1Π1 short-range state. The photoassociation (PA) spectra of the B1Π1 state, including newly observed transition to 2 vibronic levels, are obtained by high sensitivity time-of-flight mass spectrometry. Based on these PA spectra, the harmonic and anharmonic constants of vibronic states are obtained, resulting in predicted vibronic energies with an uncertainty of 1–2 cm−1. The B1Π1 (v = 3) state is found to have the maximum production rate for ground-state molecules with a value of 3(1) × 104 s−1, which is 3 times larger than the value via the previously studied 2 3 Π 0 + (v = 10, J = 0) state with two-photon cascade decay. The populations of J = 0, 1, and 2 rotational levels of X1Σ+ (v = 0) state molecules formed via the B1Π1 (v = 3, J = 1) state are measured to be around 20%, 40%, and 20%. To quantify the coupling strength between the B1Π1 (v = 3) state and X1Σ+ (v = 0) state, the transition dipole moment between them is measured to be 7.2(2) × 10−3ea0, which is also 3 times larger than the value between the 2 3 Π 0 + (v = 10) state and X1Σ+ (v = 0) state, meaning the B1Π1 (v = 3) state has a stronger coupling with the X1Σ+ (v = 0) state. Our detailed measurements provide relevant parameters for investigation on direct stimulated Raman adiabatic passage transfer between the atomic scattering state and molecular bound state for 85Rb133Cs molecules. [ABSTRACT FROM AUTHOR]

A pseudosymmetric description of the crystal lattice derived from a single wide‐angle Kikuchi pattern can have several causes. The small size (<15%) of the sector covered by an electron backscatter diffraction pattern, the limited precision of the projection centre position and the Kikuchi band definition are crucial. Inherent pseudosymmetries of the crystal lattice and/or structure also pose a challenge in the analysis of Kikuchi patterns. To eliminate experimental errors as much as possible, simulated Kikuchi patterns of 350 phases have been analysed using the software CALM [Nolze et al. (2021). J. Appl. Cryst.54, 1012–1022] in order to estimate the frequency of and reasons for pseudosymmetric crystal lattice descriptions. Misinterpretations occur in particular when the atomic scattering factors of non‐equivalent positions are too similar and reciprocal‐lattice points are systematically missing. As an example, a pseudosymmetry prediction depending on the elements involved is discussed for binary AB compounds with B1 and B2 structure types. However, since this is impossible for more complicated phases, this approach cannot be directly applied to compounds of arbitrary composition and structure. [ABSTRACT FROM AUTHOR]

We investigate the realization of the phenomenon of optomechanically induced gain in a hybrid optomechanical system consisting of an interacting Bose-Einstein condensate trapped inside the optical lattice of a cavity which is generated by an external coupling laser tuned to the red sideband of the cavity. It is shown that the system behaves as an optical transistor while the cavity is exposed to a weak input optical signal which can be amplified considerably in the cavity output if the system is in the unresolved sideband regime. Interestingly, the system has the capability to switch from the resolved to unresolved sideband regime by controlling the s-wave scattering frequency of atomic collisions. We show that the system gain can be enhanced considerably by controlling the s-wave scattering frequency as well as the coupling laser intensity while the system remains in the stable regime. Based on our obtained results, the input signal can be amplified more than 100 million percent in the system output which is much larger than those already reported in the previously proposed similar schemes. [ABSTRACT FROM AUTHOR]

The polarization dependence of the cross sections of two-photon transitions including X-ray scattering was analyzed. We developed the regular approach to the derivation of the polarization parameters of photoprocesses. Our approach is based on the tensor representation of the photon density matrix, which is written in terms of the unit vectors directed along the major axis of the polarization ellipse ( ϵ ˆ ) and the photon propagation ( k ˆ ). Explicit expressions for the product of two photon density matrices were derived. As an example, the parametrization of the polarization dependence of the X-ray scattering by closed-shell atoms is given both in terms of (i) scalar products of photon vectors ϵ ˆ 1 , 2 , k ˆ 1 , 2 and (ii) X-ray Stokes parameters. We discuss the applicability of the atomic scattering for the measurement of the polarization of X-rays. [ABSTRACT FROM AUTHOR]

The results of lidar sensing of the atmosphere at altitudes in the range of 25–600 km from the Kamchatka Lidar Station (53° N, 158° E) obtained in 2008–2022 are presented. The results of an analysis of the data of two-frequency lidar sensing of the thermosphere are given. The increased scattering at wavelengths of 532 and 561 nm is due to resonant scattering by excited atomic nitrogen and oxygen ions. Manifestations of resonant scattering in the middle atmosphere are also discussed. It is demonstrated that these ions are excited during the process of the ionization of the main atmospheric species by the precipitation of energetic electrons. The findings show that, during lidar soundings of the middle atmosphere, the ionization process can form imaginary aerosol formations. The spectrum of precipitating electrons can be estimated from the shape and position of the maximum of the lidar signal profile. It is shown that the process of the excitation of ions in the ground state does not play any significant role in the formation of the backscattered lidar signal. The signal does not carry information about the content and height profile of ions at the ground state. The appearance of resonant scattering in the atmosphere indicates the presence of the ionization sources. [ABSTRACT FROM AUTHOR]

The development in the crystal structure analysis of synthetic polymers using the hybridized combination of wide-angle X-ray and neutron diffraction (WAXD and WAND, respectively) techniques has been reviewed with many case studies performed by the authors. At first, the technical development was reviewed, in which the usage of high-energy synchrotron X-ray source was emphasized for increasing the total number of the observable diffraction peaks, and several examples were introduced. Secondly, the usage of the WAND method was introduced, in which the successful extraction of hydrogen atomic positions was described. The third example is to show the importance for the hybrid combination of these two diffraction methods. The quantitative WAXD data analysis gave the crystal structures of at-poly(vinyl alcohol) (at-PVA) and at-PVA-iodine complex. However, the thus-proposed structure models were found not to reproduce the observed WAND data very much. The reason came from the remarkable difference in the atomic scattering powers of the constituting atomic species between WAXD and WAND phenomena. The introduction of statistical disorder solved this serious problem, which reproduced both of the observed WAXD and WAND data consistently. The more systematic combination of WAXD and WAND methods, or the so-called X-N method, was applied also to the quantitative evaluation of the bonded electron density distribution along the skeletal chains, where the results about polydiacetylene single crystals were presented as the first successful study. Finally, the application of WAND technique in the trace of structural changes induced under the application of external stress or temperature was described. The future perspective is described for the development of structural science of synthetic polymers on the basis of the combined WAXD/WAND techniques. [ABSTRACT FROM AUTHOR]

In convergent beam electron diffraction (CBED) on two-dimensional (2D) materials, the intensity distributions within the individual CBED spots map the local atomic arrangements within the probed region. In this study we demonstrate that the average intensities within the CBED spots essentially depend on the scattering parameters by a single atom, thus, offering the possibility of the direct measurement of such parameters. Scattering potential of an individual atom can be approximated by the Gaussian function and its parameters, the standard deviation and the maximal phase shift, can be recovered from the ratio of the intensities in the zero- and higher orders spots in CBED pattern. In order to demonstrate this, we simulated CBED patterns and extracted the atomic scattering parameters from such patterns. In the simulated examples, no weak phase object approximation is applied and the proposed method provides accurate results even for materials with large phase shifts up to 1.5 rad, as for example tungsten. The scattering parameters recovered from the experimental CBED patterns of graphene and twisted graphene-hBN structure show good agreement with the theoretically obtained values. [Display omitted] [ABSTRACT FROM AUTHOR]

Parallel coordinates are a powerful technique to visually analyze multi-parameter data, i.e., sets of datapoints with potentially many associated parameter values per datapoint. When these sets are large, line rendering becomes a severe performance bottleneck, and since many lines fall into the same pixel the numerical precision of the color buffer is quickly reached. We propose a scalable GPU realization of parallel coordinates building upon 2D pairwise attribute bins, to significantly reduce the number of lines to be rendered. Our approach comprises a GPU compute pipeline that combines shader-based scattering with atomic increment operations to efficiently count how often a line is drawn. These counts are then used to draw all pairwise sub-plots in the parallel coordinates plot, by analytically calculating the opacity for each count and rendering a line with end points determined by the 2D coordinates of the bin. In this way, framebuffer precision issues that are paramount in classical approaches can be overcome. We demonstrate the efficiency of the proposed realization for visualizing a weather forecast ensemble comprising 2.7 billion datapoints, each carrying 7 prognostic floating-point variables like temperature, precipitation and pressure, plus spatial and simulation input variables. We compare our pipeline to a rasterization-based approach regarding performance, and demonstrate interactive brushing at 4 s per frame at full HD viewport resolution. • Parallel Coordinates Plots (PCP) useful for visual multiparameter data analysis. • Limited scalability of PCPs for datasets > 100 million data points. • Binned PCPs grow with viewport resolution instead of number of datapoints. • Utilization of modern GPUs for efficient binned parallel coordinates computation. • Combination with analytical blending to accurately handle transparency. [Display omitted] [ABSTRACT FROM AUTHOR]

III-nitride-based hot electron transistors (HETs) offer a significant promise as high-speed, high-power devices, but their performance has been limited to below that of competing technologies. Here, we report on a HET with current density > 440 kA/cm2 and common-emitter current gain >20. Polarization engineering of the emitter stack was used to allow for high-current collimated electron injection from the emitter with relatively low turn-on voltage. The use of only polarization charge in the undoped 10 nm-thick base allowed for high gain through minimization of scattering with atomic layer etching contact fabrication used to lower base access resistance. [ABSTRACT FROM AUTHOR]

All‐enzyme hydrogel (AEH) particles with a hydrodynamic diameter of up to 120 nm were produced intracellularly with an Escherichia coli‐based in vivo system. The inCell‐AEH nanoparticles were generated from polycistronic vectors enabling simultaneous expression of two interacting enzymes, the Lactobacillus brevis alcohol dehydrogenase (ADH) and the Bacillus subtilis glucose‐1‐dehydrogenase (GDH), fused with a SpyCatcher or SpyTag, respectively. Formation of inCell‐AEH was analyzed by dynamic light scattering and atomic force microscopy. Using the stereoselective two‐step reduction of a prochiral diketone substrate, we show that the inCell‐AEH approach can be advantageously used in whole‐cell flow biocatalysis, by which flow reactors could be operated for >4 days under constant substrate perfusion. More importantly, the inCell‐AEH concept enables the recovery of efficient catalyst materials for stable flow bioreactors in a simple and economical one‐step procedure from crude bacterial lysates. We believe that our method will contribute to further optimization of sustainable biocatalytic processes. [ABSTRACT FROM AUTHOR]

We study through simulations a layout mixing RF and THz technologies for a compact ultrafast X-ray pulse source based on Inverse Compton Scattering (ICS), aiming to deliver few femtoseconds to sub-femtosecond pulses. The layout consists of an S-band gun as the electron source and a dielectric-loaded circular waveguide driven by a multicycle THz pulse to accelerate and longitudinally compress the bunch, before X-ray generation via ICS with a laser pulse. We detail several schemes allowing the optimization of the electron bunch properties. This optimization leads to a preliminary layout and various working points able to deliver 0.1–5 pC bunches, ranging from 15 to 18 MeV average kinetic energy, 0.4 to 5 fs rms length, 0.1% to 2.6% rms energy spread, and 5 to 13 μm rms transverse size. Simultaneously, the beamline is kept compact (≈1.3 m up to the ICS point), which has not yet been achieved using only conventional RF technologies. The properties of the X-ray pulse are investigated with simulations, showing the possibility to tune its energy between 2.9 and 11.5 keV. For 400 mJ of laser energy, 1.5 × 104–7.7 × 104 photons/pulse in 1.5% rms bandwidth or 6.2 × 103–3.5 × 104 photons/pulse with lower bandwidths (0.56%–1.5% rms along the energy range) can be expected. The properties of the DLW and of the THz pulse driving it, the state-of-the-art of the THz pulse generation schemes, and the influence of various jitters and the limits that they should not exceed for a reasonably stable operation are finally given. [ABSTRACT FROM AUTHOR]

We present, in the relativistic regime, the results of the study of elastic scattering of hydrogen atoms in its metastable state (2S-2S) by electron impact in the absence of a laser field. In the first calculation, semi-relativistic wave functions present hydrogen states. Dirac spinor describes the incident and scattered electrons. The condition Z α < < 1 of using Darwin wave functions has been verified. The second approach uses the exact relativistic calculation of this process. The relativistic case calculations converge to those of the non-relativistic case within the low electron velocity range. In the high incoming energy range, the Coulomb effect and exchange effect are neglected. We present the relativistic differential cross-section RDCS as a function of the final scattering angle for different energies of the incident electron. The effect of atomic number Z for hydrogenoid atoms on the cross-section is examined. [ABSTRACT FROM AUTHOR]

In this paper, we have reported the calculated results of anisotropy parameter (Pl) and angular momentum transfer parameter (L⊥) for positron (electron) scattering by Calcium (Ca) atom using close coupling approximation method in the framework of R-matrix theory at 20eV. Since this theory has deep root in nuclear physics, it also provides better results in atomic and molecular physics. The authors have compared the reviewed results with available theoretical results. A good agreement between these results shows that the present method gives better understanding for the positron (electron)-atom scattering. [ABSTRACT FROM AUTHOR]

We address the existence and stability of one-dimensional (1D) holes and kinks and two-dimensional (2D) vortex-holes nested in extended binary Bose mixtures, which emerge in the presence of Leeâ€"Huangâ€"Yang (LHY) quantum corrections to the mean-field energy, along with self-bound quantum droplets. We consider both the symmetric system with equal intra-species scattering lengths and atomic masses, modeled by a single (scalar) LHY-corrected Grossâ€"Pitaevskii equation (GPE), and the general asymmetric case with different intra-species scattering lengths, described by two coupled (spinor) GPEs. We found that in the symmetric setting, 1D and 2D holes can exist in a stable form within a range of chemical potentials that overlaps with that of self-bound quantum droplets, but that extends far beyond it. In this case, holes are found to be always stable in 1D and they transform into pairs of stable out-of-phase kinks at the critical chemical potential at which localized droplets turn into flat-top states, thereby revealing the connection between localized and extended nonlinear states. In contrast, we found that the spinor nature of the asymmetric systems may lead to instability of 1D holes, which tend to break into two gray states moving in the opposite directions. Remarkably, such instability arises due to spinor nature of the system and it affects only holes nested in extended modulationally-stable backgrounds, while localized quantum droplet families remain completely stable, even in the asymmetric case, while 1D holes remain stable only close to the point where they transform into pairs of kinks. We also found that symmetric systems allow fully stable 2D vortex-carrying single-charge states at moderate amplitudes, while unconventional instabilities appear also at high amplitudes. Symmetry also strongly inhibits instabilities for double-charge vortex-holes, which thus exhibit unexpectedly robust evolutions at low amplitudes. [ABSTRACT FROM AUTHOR]

We have calculated inelastic mean free paths (IMFPs) for 14 organic compounds (26‐n‐paraffin, adenine, β‐carotene, diphenyl‐hexatriene, guanine, Kapton, polyacetylene, poly (butene‐1‐sulfone), polyethylene, polymethylmethacrylate, polystyrene, poly(2‐vinylpyridine), thymine, and uracil) and liquid water for electron energies from 50 eV to 200 keV with the relativistic full Penn algorithm including the correction of the bandgap effect in insulators. These calculations were made with energy‐loss functions (ELFs) obtained from measured optical constants and from calculated atomic scattering factors for X‐ray energies. Our calculated IMFPs could be fitted to a modified form of the relativistic Bethe equation for inelastic scattering of electrons in matter from 50 eV to 200 keV. The average root‐mean‐square (RMS) deviation in these fits was 0.17%. The IMFPs were also compared with a relativistic version of our predictive Tanuma–Powell–Penn (TPP‐2M) equation. The average RMS deviation in these comparisons was 7.2% for energies between 50 eV and 200 keV. This average RMS deviation is smaller than that found in a similar comparison for our group of 41 elemental solids (11.9%) and for our group of 42 inorganic compounds (10.7%) for the same energy range. We found generally satisfactory agreement between our calculated IMFPs and values from other calculations for energies between 200 eV and 10 keV. We also found reasonable agreement between our IMFPs for organic compounds and measured IMFPs for energies between 50 eV and 200 keV. Substantial progress for IMFP measurements for liquid water has been made in recent years through the invention of liquid water microjet photoelectron spectroscopy and droplet photoelectron imaging. We found that the IMFPs from these experiments and the associated analyses were larger than our IMFPs by factors between two and four for energies between about 30 eV and 1000 eV. The energy dependences of the measured IMFPs are, however, similar to that of our IMFPs in the same energy range. Since IMFPs calculated from the same algorithm for a number of inorganic compounds agree reasonably well with measured IMFPs for energies between 100 eV and 200 keV, the large differences between IMFPs for water from recent experiments and our results are surprising and need to be resolved with additional experiments. [ABSTRACT FROM AUTHOR]

The analytical structure, absolute value, and angular anisotropy of the double differential cross section for bremsstrahlung at the nonresonant inelastic scattering of an X-ray photon by a multicharged helium-like atomic ion have been theoretically predicted. [ABSTRACT FROM AUTHOR]

New structure determinations of CuSO4, CuSO4·H2O, CuSO4·3H2O and CuSO4·5H2O are reported from X-ray diffraction experiments at 100 (1) K. Combined density functional theory (ORCA) and non-spherical atomic scattering factor (NoSpherA2) computations enabled a Hirshfeld Atom Refinement (HAR) using custom atom scattering factors, accurately polarized and charge-compensated atom electron densities and accurate placement and shapes of the water hydrogen atoms. The results clearly demonstrate that all H atoms are involved in conventional H-bonding in the structures of the hydrates, contrary to an early X-ray diffraction determination on CuSO4·3H2O. Comparison to neutron diffraction results demonstrates the efficacy of this new HAR method. Colour variation in copper sulfates is interpretable by considering the relative number of sulfato and aqua ligands, given the lower crystal field splitting of the former relative to the latter. [ABSTRACT FROM AUTHOR]

Collisions between K(12p) Rydberg atoms and CH3NO2 target molecules are studied. Whereas CH3NO2 can form long-lived valence-bound CH3NO-2 ions, the data provide no evidence for production of long-lived K+± ± ± CH3NO-2 ion pair states. Rather, the data show that collisions result in unusually strong Rydberg atom scattering. This behavior is attributed to ion-ion scattering resulting from formation of transient ion pair states through transitions between the covalent K(12p) + CH3NO2 and ionic K+ + (dipole bound) CH3NO-2 terms in the quasimolecule formed during collisions. The ion-pair states are destroyed through rapid dissociation of the CH3NO-2 ions induced by the field of the K+ core ion, the detached electron remaining bound to the K+ ion in a Rydberg state. Analysis of the experimental data shows that ion pair lifetimes &10 ps are sufficient to account for the present observations. The present results are consistent with recent theoretical predictions that Rydberg collisions with CH3NO2 will result in strong collisional quenching. The work highlights a new mechanism for Rydberg atom scattering that could be important for collisions with other polar targets. For purposes of comparison, results obtained following K(12p)-SF6 collisions are also included. [ABSTRACT FROM AUTHOR]

It is shown that the Klein–Nishina–Tamm equation determines the total intensity of coherent and incoherent X‐ray scattering. The change in the ratio of these components during the transition from scattering on a resting electron to scattering on the atomic electrons is estimated. Taking into account the innovations, the required ratio is calculated for the atom of three elements with a limited set of scattering angles. The basic expression for incoherent scattering in the Klein–Nishina–Tamm equation allows us to agree, in the first approximation, the calculated value of the total scattering intensity with the experimentally observed results. The current dependences for the intensity of coherent and incoherent x‐ray scattering on the massive multicomponent materials are presented. [ABSTRACT FROM AUTHOR]

On the occasion of the 150th anniversary of Ernest Rutherford's birth I discuss how indistinguishabilty profoundly affects the collisions of identical particles. In the case of a Coulombic interaction this leads to a dramatic modification of Rutherford's famous scattering formula as predicted by Nevill Mott. An even more extreme example is provided by a low-energy scattering experiment of identical fermions interacting via a short range potential. Here indistinguishability will make or break the observation of scattered particles. This fascinating phenomenon has been observed using a laser-based collider for ultracold fermionic potassium atoms. [ABSTRACT FROM AUTHOR]

Schreibersite, (Fe,Ni)3P, the most abundant cosmic phosphide, is a principal carrier of phosphorus in the natural Fe-Ni-P system and a likely precursor for prebiotic organophosphorus compounds at the early stages of Earth's evolution. The crystal structure of the mineral contains three metal sites allowing for unrestricted substitution of Fe for Ni. The distribution of these elements across the structure could serve as a tracer of crystallization conditions of schreibersite and its parent celestial bodies. However, discrimination between Fe (Z = 26) and Ni (Z = 28) based on the conventional X-ray structural analysis was for a long time hampered due to the proximity of their atomic scattering factors. We herein show that this problem has been overcome with the implementation of area detectors in the practice of X-ray diffraction. We report on previously unknown site-specific substitution trends in schreibersite structure. The composition of the studied mineral encompasses a Ni content ranging between 0.03 and 1.54 Ni atoms per formula unit (apfu): the entire Fe-dominant side of the join Fe3P-Ni3P. Of 23 schreibersite crystals studied, 22 comprise magmatic and non-magmatic iron meteorites and main group pallasites. The near end-member mineral (0.03 Ni apfu) comes from the pyrometamorphic rocks of the Hatrurim Basin, Negev desert, Israel. It was found that Fe/Ni substitution in schreibersite follows the same trends in all studied meteorites. The dependencies are nonlinear and can be described by second-order polynomials. However, the substitution over the M2 and M3 sites within the most common range of compositions (0.6 < Ni <1.5 apfu) is well approximated by a linear regression: Ni(M2) = 0.84 × Ni(M3) - 0.30 apfu (standard error 0.04 Ni apfu). The analysis of the obtained results shows a strong divergence between the variation of unit-cell parameters of natural schreibersite and those of synthetic (Fe,Ni)3P. This indicates that Fe/Ni substitution trends in the mineral and its synthetic surrogates are different. A plausible explanation might be related to the differences in the system equilibration time of meteoritic schreibersite (millions of years) and synthetic (Fe,Ni)3P (~100 days). However, regardless of the reason for the observed difference, synthetic (Fe,Ni)3P cannot be considered a structural analog of natural schreibersite, and this has to be taken into account when using synthetic (Fe,Ni)3P as an imitator of schreibersite in reconstructions of natural processes. [ABSTRACT FROM AUTHOR]

In this paper, we consider the effects of bound atomic electrons scattered by solar neutrinos due to the electromagnetic properties of neutrinos. This necessitates considering the recoil of atomic nucleus, which should be considered in the momentum conservation, but the effect to the energy conservation is negligible. This effect changes the kinematic behavior of the scattered electron compared to that scattered on free electrons. We apply this effect to the recent XENON1T data, but the bounds obtained from this are not very restrictive. We obtained the bounds: the (transition) magnetic moment | f α β | ≤ 0. 8 6 × 1 0 − 7 (times the electron Bohr magneton) and the charge radius | r ̃ | < 4. 3 0 × 1 0 − 1 7 cm. For a nonvanishing millicharge () , the allowed bound is shown in the r ̃ 2 − plane. [ABSTRACT FROM AUTHOR]

The design of a high-efficiency mass spectrometer is described, aimed at residual gas detection of low mass species using low-energy electron impact, with particular applications in helium atom microscopy and atomic or molecular scattering. The instrument consists of an extended ionization volume, where electrons emitted from a hot filament are confined using a solenoidal magnetic field to give a high ionization probability. Electron space charge is used to confine and extract the gas ions formed, which are then passed through a magnetic sector mass filter before reaching an ion counter. The design and implementation of each of the major components are described in turn, followed by the overall performance of the detector in terms of mass separation, detection efficiency, time response, and background count rates. The linearity of response with emission current and magnetic field is discussed. The detection efficiency for helium is very high, reaching as much as 0.5%, with a time constant of (198 ± 6) ms and a background signal equivalent to an incoming helium flux of (8.7 ± 0.2) × 106 s−1. [ABSTRACT FROM AUTHOR]

Positron scattering on atomic and molecular targets is a two-centre problem due to the possibility of rearrangement (Ps-formation) processes. In certain kinematic regions, single-centre expansion methods can be applied to two-centre scattering problems. In such approaches, however, information about Ps-formation and direct ionization processes are combined into excitation amplitudes of positive-energy pseudostates. In this report we show that Ps-formation amplitudes can be extracted using the total scattering wave function, which we reconstruct from single-centre convergent close-coupling calculations. The method is applied to positron scattering from hydrogen and lithium atomic targets. Excellent agreement with the two-centre theoretical benchmark results show the validity of the proposed technique. [ABSTRACT FROM AUTHOR]

In contrast to rapidly quenched metallic glasses, nanoglasses consist of two components, namely amorphous nanograins and interfacial regions with distinctively different properties. Various physical methods have been employed to obtain information on the atomistic and magnetic properties of such materials. For the case of a Fe50B50 nanoglass, using high-energy X-ray diffraction, it was found that the short-range order of the nanograins is similar to that of a crystalline FeB alloy. Magnetic Compton scattering shows that the total magnetic moment is the sum of the magnetic moment of the nanograins and the weak magnetic moment of the interfacial regions (μInterface=+0.08 μB). The measured moment of boron agrees (μBoron=+0.08 μB) with linear Muffin-Tin calculations. From the results of Mössbauer and magnetic Compton scattering, it can be concluded that the boron atoms segregate in the interfacial regions, resulting in a reduced boron concentration in the nanograins. [ABSTRACT FROM AUTHOR]

We report absolute elastic differential cross sections for electron interactions with the C4F6 isomers, hexafluoro-1,3-butadiene (1,3-C4F6), hexafluoro-2-butyne (2-C4F6), and hexafluorocyclobutene (c- C4F6). The incident electron energy range is 1.5-200 eV, and the scattered electron angular range for the differential measurements varies from 15° to 150°. In all cases the absolute scale of the differential cross section was set using the relative flow technique, with helium as the reference species. Atomic-like behaviour in these scattering systems is shown here for the first time, and is further investigated by comparing the elastic cross sections for the C4F6 isomers with other fluorinated molecules, such as SF6 and CnF6 (n = 2, 3, and 6). We note that for all the six-F containing molecules, the scattering process for electron energies above 30 eV is indistinguishable. Finally, we report results for calculations of elastic differential cross sections for electron scattering from each of these isomers, within an optical potential method and assuming a screened corrected independent atom representation. The level of agreement between these calculations and our measurements is found to be quite remarkable in all cases. [ABSTRACT FROM AUTHOR]

We have investigated the origin of superstructure peaks as observed by X-ray diffraction of multiferroic Bi(Fe0.5Cr0.5)O3 thin films grown by pulsed laser deposition on single crystal SrTiO3 substrates. The photon energy dependence of the contrast between the atomic scattering factors of Fe and Cr is used to rule out a chemically ordered double perovskite Bi2FeCrO6 (BFCO). Structural calculations suggest that the experimentally observed superstructure occurs due to unequal cation displacements along the pseudo-cubic [111] direction that mimic the unit cell of the chemically ordered compound. This result helps to clarify discrepancies in the correlations of structural and magnetic order reported for Bi2FeCrO6. The observation of a superstructure in itself is not a sufficient proof of chemical order in double perovskites. [ABSTRACT FROM AUTHOR]

A comparison of five X-ray structures of transition-metal-bound hydride complexes, successfully refined using Hirshfeld Atom Refinement (HAR) against low resolution X-ray diffraction data (including the positions and ADPs of all hydrogen atoms), with neutron structures shows that using aspherical atomic scattering factors instead of spherical ones results in systematic elongation of metal–hydrogen bonds, which in the case of the highest-quality data leads to excellent agreement of the X-ray and the neutron-derived bond lengths. [ABSTRACT FROM AUTHOR]

DO3 disorder is essential to elucidate the properties of many 3d group Heusler alloys, especially Mn2-based alloys. The DO3 disorder for Mn2FeAl, corresponding to the exchange between Mn and Fe atoms, is difficult to distinguish with the normal x-ray diffraction instrument because of similar atomic scattering factors for Mn and Fe atoms. However, via the observation of magnetic behavior, the DO3 disorder has been observed indirectly. Many pieces of evidence show the existence of DO3 disorder in our samples. A qualitative method is employed to clarify the degree of DO3 disorder for Mn2FeAl alloys with the results of first-principles calculations, and this method can be applied to many Mn2-based alloys. In addition, full ordering occupation of Al atoms has been observed and Mn2FeAl without any disorder could be prepared hopefully for further work. [ABSTRACT FROM AUTHOR]

A method for generating the atomic pair distribution function (PDF) from powder diffraction data by the removal of instrument contributions, such as Kα2 from laboratory instruments or peak asymmetry from neutron time‐of‐flight data, has been implemented in the computer programs TOPAS and TOPAS‐Academic. The resulting PDF is sharper, making it easier to identify structural parameters. The method fits peaks to the reciprocal‐space diffraction pattern data whilst maximizing the intensity of a background function. The fit to the raw data is made 'perfect' by including a peak at each data point of the diffraction pattern. Peak shapes are not changed during refinement and the process is a slight modification of the deconvolution procedure of Coelho [J. Appl. Cryst. (2018), 51, 112–123]. Fitting to the raw data and subsequently using the calculated pattern as an estimation of the underlying signal reduces the effects of division by small numbers during atomic scattering factor and polarization corrections. If the peak shape is sufficiently accurate then the fitting process should also be able to determine the background if the background intensity is maximized; the resulting calculated pattern minus background should then comprise coherent scattering from the sample. Importantly, the background is not allowed complete freedom; instead, it comprises a scan of an empty capillary sample holder with a maximum of two additional parameters to vary its shape. Since this coherent scattering is a calculated pattern, it can be easily recalculated without instrumental aberrations such as capillary sample aberration or Kα2 from laboratory emission profiles. Additionally, data reduction anomalies such as incorrect integration of data from two‐dimensional detectors, resulting in peak position errors, can be easily corrected. Multiplicative corrections such as polarization and atomic scattering factors are also performed. Once corrected, the pattern can be scaled to produce the total scattering structure factor F(Q) and from there the sine transform is applied to obtain the pair distribution function G(r). [ABSTRACT FROM AUTHOR]

In this work, we develop a new methodology for hypersonic multi-body free-flight experimentation and conduct several tests to explore the aerodynamic separation of equal-sized spherical fragments, which approximates the atmospheric disruption of meteoroids. A novel suspension design enabled by 3D printing is introduced, allowing for rapid, reliable release of clustered spheres into hypersonic flow, and high-speed stereoscopic imagery is employed to visualize the aerodynamically separating spheres. A new data-reduction technique based on synthetic image fitting, along with previous edge-detection and photogrammetric reconstruction methods, is used to track sphere motions; these motions also anchor a novel self-calibration procedure for the camera apparatus. To probe the separation characteristics of disrupted meteoroids with increasing fragment population, clusters of 4, 11, and 36 equal-sized spheres are subjected to Mach 6 flow. Strong dependence of trajectories on subcluster interactions is discerned for both 4 and 11 spheres, with two-body lifting pairs identified as critical arrangements capable of producing outlying fragments, whereas the initial stage of mutual repulsion is observed to exert greater influence as the cluster population is increased. Finally, terminal lateral velocity measurements are compared with other studies to synthesize a coherent picture of separation trends for equal-sized bodies. [ABSTRACT FROM AUTHOR]

Transmission of 1-MeV protons through a conical borosilicate macrocapillary was simulated. In present simulations we included atomic scatterings and patch deflections, different from pioneer work where only the former was considered. The simulated results provide deep insight into the transmission mechanisms of MeV ions through a conical macrocapillary: for tilt angles smaller than the taper angle, the enhanced transmission is fully governed by atomic scatterings, whereas beyond the taper angle the patch deflections are of some importance. Moreover, the strength of patch deflections was found to first increase to a maximum and then drop to zero as the tilt angle increases. This is different from those of the atomic scatterings and geometric laws, which both monotonously decrease with the tilt angle. The core and halo structure in the transmission profile unique to the MeV ions through the conical capillary can be formed only for smaller beam divergence. [ABSTRACT FROM AUTHOR]

We present version 10 of the CHIANTI package. In this release, we provide updated atomic models for several helium-like ions and for all the ions of the beryllium, carbon, and magnesium isoelectronic sequences that are abundant in astrophysical plasmas. We include rates from large-scale atomic structure and scattering calculations that are in many cases a significant improvement over the previous version, especially for the Be-like sequence, which has useful line diagnostics to measure the electron density and temperature. We have also added new ions and updated several of them with new atomic rates and line identifications. Also, we have added several improvements to the IDL software, to speed up the calculations and to estimate the suppression of dielectronic recombination. [ABSTRACT FROM AUTHOR]

Powder X‐ray diffraction has some inherent advantages over traditional single‐crystal X‐ray diffraction in accurately determining electron densities and structural parameters due to the lower requirements for sample crystallinity, simpler corrections and measurement simultaneity. For some simple inorganic materials, it has been shown that these advantages can compensate for disadvantages such as peak overlap and error‐prone background subtraction. Although it is challenging to extend powder X‐ray diffraction‐based electron‐density studies to organic materials with significant peak overlap, previous results using a dedicated vacuum diffractometer with a large image‐plate camera (AVID) demonstrated that it can be done. However, the vacuum setup with the off‐line detector system was found to prohibit a widespread use. Fast microstrip detectors, which have been employed at a number of powder diffraction beamlines, have the potential to facilitate electron‐density studies. Nevertheless, no electron‐density studies even for materials with slight peak overlap have been performed with microstrip detectors. One of the most critical problems has been a difference in sensitivity between microstrip channels, which substantially defines the dynamic range of a detector. Recently, a robust approach to this problem has been developed and applied to a total scattering measurement system (OHGI) with 15 MYTHEN microstrip modules. In the present study, synchrotron powder X‐ray diffraction data obtained with OHGI are evaulated in terms of multipole electron densities and structural parameters (atomic positions and displacement parameters). These results show that, even without a dedicated setup and perfect samples, electron‐density modelling can be carried out on high‐quality powder X‐ray diffraction data. However, it was also found that the required prior information about the sample prohibits widespread use of the method. With the presently obtainable data quality, electron densities of molecular crystals in general are not reliably obtained from powder data, but it is an excellent, possibly superior, alternative to single‐crystal measurements for small‐unit‐cell inorganic solids. If aspherical atomic scattering factors can be obtained from other means (multipole databases, theoretical calculations), then atomic positions (including for hydrogen) and anisotropic atomic displacement parameters (non‐hydrogen atoms) of excellent accuracy can be refined from synchrotron powder X‐ray diffraction data on organic crystals. [ABSTRACT FROM AUTHOR]

Dirac relativistic partial wave analysis has been employed to analyze the angular distributions and critical minima, along with maximum spin polarization, for the elastic scattering of electrons from copper atoms over the energy range of 1 to 2000 eV. Integrated elastic, inelastic, total, and momentum transfer cross sections have also been calculated. This work uses a complex electron‐atom optical potential that includes static, exchange, correlation‐polarization, and absorption potentials. Comparison of our calculations with the available experimental data and other theoretical calculations shows satisfactory agreement. As far as we are concerned, critical minima and corresponding maximum spin polarization points have not yet been reported in the literature. [ABSTRACT FROM AUTHOR]

The mean inner potential (V 0) of crystals plays an important role in electron microscopy. In a few cases, it has been measured experimentally, using mostly electron holography; however, it is not uncommon to find reports that disagree by a few volts regarding the mean inner potential of the same material. Different levels of theory have also been used to estimate its value, often by building the crystal as a superposition of isolated atoms or ions—an independent-atom approximation that does not take bonding into account. In a few cases, density-functional theory (DFT) calculations were done to capture such bonding, frequently using computer-intensive all-electron approaches. In this article, we describe in detail a faster implementation based on postprocessing files produced by a DFT code that relies on the projector-augmented wave method. We deployed this approach to compute values of V 0 for 44 elemental solids, and we provide the first quantum-mechanical calculation of the mean inner potential beyond the independent-atom approximation for many of them. We also report instances in which different surface terminations for the same material led to differences in V 0 of more than 3 V, highlighting the dependence of the mean inner potential on the boundary conditions of the sample. Finally, by comparing our values of V 0 with other material properties, we show that it correlates mostly linearly with the mass density, that it can be used to compute a good approximation to the orbital diamagnetic contribution to the magnetic susceptibility, and that it provides a simple route to compute atomic scattering amplitudes for forward scattering of electrons. • We present an accurate method to compute the mean inner potential (MIP) of crystals. • We applied our method to efficiently compute the MIP of 44 elemental crystals. • We analyzed the correlation between mass density and MIP in solids. • We approximated the diamagnetic orbital susceptibility of crystals from our MIP values. • We did this also for the atomic factors for forward scattering of electron beams. [ABSTRACT FROM AUTHOR]

The behavior of liquids has always been a subject of strong interest and still presents many challenging issues. A paradigmatic example is the understanding of their atomic-scale collective dynamics. Experimentally accessible to inelastic neutron and X-ray scattering, this regime has recently disclosed an unexpectedly rich scenario made up of more than one collective excitation. However, experiments lack a fundamental piece of information since they cannot distinguish the longitudinal or transverse nature of the detected modes. Here we present an inelastic neutron scattering study of the atomic dynamics of water and sulfuric acid, two prototypes of hydrogen bonded liquids. We propose a novel method that allows the experimental determination of the nature of the observed modes, without resorting to any indirect information. The dynamic structure factors show a complex collective dynamics, with two propagating excitations that we describe in the framework of an interacting-modes model. The first high-energy excitation is usually assumed to be the prolongation of the longitudinal acoustic mode and is characterized by a strong fast sound, which in turn we ascribe to the interaction with the second low-energy mode. Our approach confirms the main longitudinal nature of the first mode and unambiguously identifies the transverse nature of the second one. Finally, the lifetime of the modes suggests a common origin for the second mode, possibly related to the presence of the hydrogen bond network. • Comparative analysis between THz dynamics of water and sulfuric acid. • New method to determine the longitudinal or transverse nature of the observed modes. • Complex dynamics and role of H-bonds. [ABSTRACT FROM AUTHOR]