Search

A theoretical study of the K-shell ionization of hydrogen-like ions, colliding with bare nuclei, is performed within the framework of the time-dependent Dirac equation. Special emphasis is placed on the ionization probability that is investigated as a function of impact parameter, collision energy and nuclear charge. To evaluate this probability in a wide range of collisional parameters we propose a simple analytical expression for the transition amplitude. This expression contains three fitting parameters that are determined from the numerical calculations, based on the adiabatic approximation. In contrast to previous studies, our analytical expression for the transition amplitude and ionization probability accounts for the full multipole expansion of the two-center potential and allows accurate description of nonsymmetric collisions of nuclei with different atomic numbers, $Z_1 \neq Z_2$. The calculations performed for both symmetric and asymmetric collisions indicate that the ionization probability is reduced when the difference between the atomic numbers of ions increases., 8 pages, 6 figures

We present relative cross section measurements of the inner-shell ionization of highly charged chromium ions by high-energy (7–30 keV) electrons. The measurements use a technique based on high-resolution X-ray spectroscopy, which correlates ionization events with Kα decay X-rays. Moreover, the measurements show that inner-shell ionization only affects the strength of the heliumlike 1s2s 3S1 → 1s2 1S0 forbidden line. The cross sections inferred for Li-like Cr21+ agree well with distorted wave calculations.

Mg K-shell x-ray production cross sections have been investigated for the impact of H+, He2+ and highly charged heavy ions Xe20+ and Eu20+ in the energy range near the Bohr velocity. The x-ray production cross sections were extracted from the yield and compared with various theoretical calculations. It is found that, with the same incident energy per nucleon, the cross section induced by light ions is lower than that produced by highly charged heavy ions by a factor of about 104. With the impact of H+ and He2+ ions, the x-ray emission cross section can be well predicted by ECPSSR theory. However, for the bombardment of highly charged heavy ions, the BEA calculation, corrected both by Coulomb repulsion and effective nuclear charge, results in a good estimation to the experimental data.

Molecular structures and properties of the binary clusters containing twelve boron atoms mixed with n lithium atoms, B12Lin with n = 1–14, were investigated using density functional theory with the TPSSh functional and the 6-311+G(d) basis set. Energetic parameters including relative energies, average binding energies and second-order energies of the entire series were predicted using the coupled-cluster theory (U)CCSD(T) in conjunction with the cc-pVTZ basis set. Several lowest-lying isomers were determined for each size B12Lin whose energies differ from each other by

Core ionization of DNA begins a cascade of events which could lead to cellular inactivation or death. The created core-hole following an impulse inner-shell ionization of molecules naturally decays in the auger timescale. We simulated charge migration (CM) phenomena following an impulsive core ionization of individual DNA bases at the oxygen K-edge which occurs before Auger decay of the oxygen. Our approach is based on real-time time dependent density functional theory (RT-TDDFT). It is shown that the pronounced hole fluctuation observed around bonds of the initial core-hole results in various valence orbital migrations. Also, the same photo-core-ionized dynamics is studied for the related base pairs. We investigate the role of base pairing and H-bonding interactions in the attosecond CM dynamics. In particular, the creation of a core-hole in the oxygen involved in H-bonding leads to an enhancement of charge migration relative to the respective single bases. Importantly, the hole oscillation of the adenine-thymine base pair upon creation of a core-hole at the oxygen, which does not contribute to the donor-acceptor interactions (not H-bonded), decreases compared to the single thymine base. Understanding the detailed dynamics of the localized core-hole initiating CM process would open the way for chemically controlling DNA damage/repair in the future.

By considering the example of the $${}^{229}$$ Th nucleus, which is the most probable candidate for the future frequency standard, it is shown that the properties of the electron shell should be taken into account in dealing with the interaction of the nucleus. New experimental results are analyzed. Information about the contribution of the $$E$$ 2 component to electromagnetic isomer decay is extracted. A probable solution to the thorium puzzle is considered. First, it is indicative of the first ever observation of the dependence of the nuclear-isomer lifetime on ambient conditions. Second, it demonstrates the smoothing role of single-electron levels, which renders the resonance amplification of the electron–nucleus interaction more probable.

The measurements of K-shell ionization cross sections for Fe, Ni, and Zn were performed using 7–29 keV electron impact on thick targets. Monte Carlo simulations were employed to correct the effects due to the multiple-scattered electrons and bremsstrahlung photons as well as other secondary particles within the thick targets. The so-called Tikhonov regularization method was adopted to deal with the ill-posed inverse problem involved in the thick-target method. The experimental results were compared with the DWBA and PWBA-C-Ex predictions as well as existing experimental data from the literature. It is observed that our experimental data are in better agreement with the theoretical results based on the DWBA model developed by Bote et al.

We present a new experimental method for measuring inner-shell ionization cross sections of low-charged ions colliding with hydrogen gas target in a storage ring. The method is based on a calibration by the well-known differential cross sections of proton elastic scattering on nuclei. K-shell ionization cross section of 1047(100) barn for the 95 MeV/u 58Ni19+ ions colliding with hydrogen atoms was obtained in this work. Compared to the measured ionization cross section, a good agreement is achieved with the prediction by the Relativistic Ionization CODE Modified program (RICODE-M).

Experimental data on the orbital binding energies in each of electron subshells of rare-earth elements from lanthanum to lutetium including the first ionization potentials have been analyzed in detail using a semiclassical method to separate the dependences of binding energies on the atomic number and quantum numbers. The spread of experimental data for the N and O shells of lanthanides has been discussed. The analysis has confirmed the law of similarity of orbital binding energies in the atomic number in individual subshells that differs from Moseley’s law. Deviation from the common dependence usually indicates the inaccuracy of the corresponding measurement. The simplest interpolation of the found relations makes it possible to approximate experimental data with an accuracy of about 1%, to reconstruct missed data, and to correct inaccurate measurement results. The analysis of theoretical results also reveals such relations and their violation is attributed to the violation of the order of filling of 4f states.

Processes involving the ionization of atomic shells and x-ray transitions in daughter nuclei and accompanying alpha decay of superheavy isotopes are considered. The probabilities for $$N$$ -shell ionization during the decay of isotopes entering into the tennessine ( $${}^{294}_{117}$$ Ts) and oganesson ( $${}^{294}_{118}$$ Og) alpha-decay chains are calculated. The Dirac–Fock method is used, and all multipole transitions and alpha-particle tunneling through the atomic Coulomb barrier are taken into account. The results of these calculations are analyzed and are compared with the $$K$$ -, $$L$$ -, and $$M$$ -shell ionization probabilities. The energies of the x-ray $$K_{\alpha_{1,2}}$$ lines are calculated for superheavy elements appearing as products of alpha decay in the $${}_{117}^{294}$$ Ts and $${}_{118}^{294}$$ Og chains. The Breit interaction and higher order electrodynamic corrections are taken into account. It is found that the energy of the $$K_{\alpha_{1}}$$ line of the meitnerium isotope $${}^{268}_{109}$$ Mt agrees within 0.01 keV with the results of earlier calculations. This indicates that the line observed at the GSI laboratory (Darmstadt) at an energy that is higher than the respective theoretical value by 3.2 keV does not admit an identification with the $$K_{\alpha_{1}}$$ line of $${}^{268}_{109}$$ Mt.

Atoms are made up of electrons, protons and neutrons, the most important Subatomic particles. The electron is an elementary particle and the proton and neutron consist of two different kinds of elementary particles (up and down quarks). But we do not know the structure of the electron, proton, and neutron. Saleh Theory defines a structure for electron as a hollow sphere, for proton as continuous texture and the neutron as a proton core and Electron shell. And these entire particles are made of the photon. Here we have defined the structure for the photon that has about 14 billion years old. Of course, the photon with 14 billion years old should have the structure. Saleh Theory has defined the structure for the photon as some very small particles, named “Saleh particle”, rotating around the center’ named as “Cidtone”. With this definition, Saleh Theory is going to explain the photon with a different color.

This work presents results of experiments aimed to measure total L X-ray production cross sections due to the impact of 1.335 MeV to 1.835 MeV protons on Sr, Y, Zr, Nb, and Mo, which were contrasted with previously published experimental data and theoretical predictions of the ECPPSR model and a universal fit recently proposed. Two atomic parameters databases were also used, as well as a correction due to multiple ionization (MI) of outer atomic shells. The measured cross sections are higher than all measured and theoretical values, being better described by the ECPSSR model with MI adjustments. However, when uncertainties of the used atomic parameters are considered, it is seen that it is impossible to determine the accuracy of the models with regard to the experimental values.

Cross sections for target Ar K-shell ionization associated with single and double electron capture, as well as the same cross sections corresponding to projectile F K X-rays and the total cross sections for single and double capture, were determined for 1.8–2.2 MeV/u F 9 + , 8 + , 7 + projectiles. This work was performed at Western Michigan University using the tandem Van de Graaff accelerator. Coincidences between emitted X-rays and their corresponding charge-changed particles were detected. The Ar K X-ray coincidence cross section ratios for double to single capture are found to depend strongly on the incident charge state, with the ratios for F 9 + well exceeding unity. Possible explanations for this anomalous behavior are discussed but a conclusive explanation is not found. The results are compared to previous experiments using fully-stripped fluorine where coincidence techniques were not employed.

The kinetic energy of electrons and the potential energy of a nitrogen atom with open electron shell are calculated in this work in the basis of the Slater functions using the Hartree–Fock–Roothaan (HFR) method. Analytical expressions are derived for the kinetic and potential energies of the nitrogen atom with open electron shell. Twenty independent determinant wave functions corresponding to the 1s22s22p3 electronic configuration of the nitrogen atom have been found by summing the moment projections. The results obtained have been verified using the virial theorem and the expression $$ \left(\overline{V}/\overline{T}=-2\right) $$ .

The experimentally determined atomic ionization potentials IP1 of lanthanides and actinides are analyzed. A semiclassical method is used to determine the dependence of the orbital binding energies on the atomic number Z and on quantum numbers. Features revealed for chemical elements with the regularly filled 4f and 5f shells allow approximating the dependences IP1(Z) with an error less than 1% using three fitting parameters for lanthanides and one for actinides, respectively. The revealed features for valence electrons justify a general atomic number scaling law for orbital binding energies, which is valid for both outer and inner electron shells with the regular filling.

By proposing a numbering of the twenty proteinogenic amino acids deduced from the physicochemical properties of the four coding DNA nucleobases, it is established that this amino acid number, equal to 5x entities, is not arbitrary. Indeed, we demonstrate that many attributes of these twenty amino acids, as a whole, are also 5x in number and that by isolating, since their numbering, the 3x peripheral amino acids from the 2x internal ones, these attributes are divided into ratios of 3/2 as exact value. This is verified both as the physicochemical properties of the 20 amino acids and as the coding configurations of the nucleobases, the source of this numbering., En proposant une numérotation des vingt acides aminés protéinogènes déduite des propriétés physico-chimiques des quatre nucléobases codantes de l'ADN, il est établi que ce nombre d'acides aminés, égal à 5x entités, n'est pas arbitraire. En effet, nous démontrons que de nombreux attributs de ces vingt acides aminés, dans leur ensemble, sont également au nombre de 5x et qu'en isolant, depuis leur numérotation, les 3x acides aminés périphériques des 2x internes, ces attributs sont répartis dans des rapports de 3 /2 comme valeur exacte. Ceci se vérifie à la fois avec les propriétés physico-chimiques des 20 acides aminés et avec les configurations codantes des nucléobases, source de cette numérotation.

Echoing classical physics, quantum electrodynamics predicts the release of a spectral continuum of electromagnetic radiation upon the sudden acceleration of charged particles in quantum matter. Despite apparent theoretical success in describing sister nuclear processes, known as internal bremsstrahlung, following nuclear beta decay and K capture, the situation of the photoejection of an electron from an inner shell of an atom, intraatomic bremsstrahlung (IAB), is far from settled. In this paper we present fresh measurements which rely on contemporary signal processing as well as the high flux available from a synchrotron radiation source to revisit the problem by photoejecting electrons from the innermost shell of copper. For the first time we have sufficient sample statistics to measure the expected spectra at the level expected by contemporary theory. Furthermore, we employ sufficiently thin targets to overcome secondary scattering artifacts. Our approach applies the fluorescence coincidence method to guard against extraneous scattering and multiple incident photon processes. Our observations set a severe upper limit on the rate for IAB: We conclude that current theory overpredicts, by at least 5 sigma, the measured rate for K shell IAB in copper in the range of detected energies below the K fluorescence energy.

Physical review / A 104(5), 053107 (2021). doi:10.1103/PhysRevA.104.053107, Experimental cross sections for $m$-fold photodetachment ($m=3-6$) of silicon anions via $K$-shell excitation and ionization were measured in the photon-energy range of 1830-1900~eV using the photon-ion merged-beams technique at a synchrotron light source. All cross sections exhibit a threshold behavior that is masked by pre-threshold resonances associated with the excitation of a $1s$ electron to higher, either partly occupied or unoccupied atomic subshells. Results from multi-configuration Dirac-Fock (MCDF) calculations agree with the experimentally derived cross sections for photo-absorption if small energy shifts are applied to the calculated resonance positions and detachment thresholds. Moreover, a systematic approach is applied for modeling the deexcitation cascades that set in after the initial creation of a $K$-shell hole. The resulting product charge-state distributions compare well with the measured ones for direct $K$-shell detachment but less well for resonant $K$-shell excitation. The present results are potentially useful for identifying silicon anions in cold plasmas such as interstellar gas clouds., Published by Inst., Woodbury, NY

In this work, step-by-step high-pressure high-temperature annealing of plastically deformed-type IaAB diamonds from the Istok placer has been performed and the behavior of characteristic centers has been investigated by infrared, electron paramagnetic resonance, and photoluminescence spectroscopies. A new paramagnetic center with one magnetically inequivalent position and hyperfine structure from one hydrogen atom has been found. This paramagnetic center can be assigned to the dangling carbon bond in the dislocation core, and the hydrogen hyperfine structure is due to the polarization of the electron shell of hydrogen forming the C–H bond. For this center and W7 center, the annealing temperatures have been determined. Spin relaxation was studied by pulse electron paramagnetic resonance technique at low temperatures. The spin–spin relaxation times for the W7 and 490.7 centers exclude exchange interactions between the paramagnetic centers. At the same time, the close spin–lattice relaxation times for these centers can be determined by the distorted structure near the dislocation core.

The aim of this study was to determine whether membrane lipid peroxidation in mammalian cells is enhanced by X-ray irradiation at the K-shell resonance absorption peak of phosphorus. A549 and wild-type p53-transfected H1299 (H1299/wtp53) cell lines derived from human lung carcinoma were irradiated with monoenergetic X-rays at 2.153 keV, the phosphorus K-shell resonance absorption peak, or those at 2.147 or 2.160 keV, which are off peaks. Immunofluorescence staining for 4-hydroxy-2-nonenal (HNE), a lipid peroxidation product, was used as marker for protein modification. In both cell lines, the HNE production was significantly enhanced after irradiation at 2.153 keV compared to sham-irradiation. The enhancement (E) was calculated as the ratio of the fluorescence intensity of irradiated cells to that of sham-irradiated cells. In both the cell lines, E2.153 was significantly larger than E2.147 and no significant difference between E2.147 and E2.160 was observed. The extra enhancement at 2.153 keV was possibly caused by energy transition within the phosphorus K-shell resonance absorption. Our results indicate that membrane lipid peroxidation in cells is enhanced by the Auger effect after irradiation at the K-shell resonance absorption peak of phosphorus rather than by the photoelectric effect of the constituent atoms in the membrane lipid at 2.147 keV.

Molecular dynamics simulation was employed in this study to investigate the atomistic mechanisms involved in the Ni–Al alloy homogeneous deformation and the mechanical properties of single-crystal Ni–Al under periodic boundary conditions (until the fracture begins). It is the objective of the present study to develop a simple mathematical model for calculating stress similar to molecular dynamics simulation while the effects of the components of the interatomic potential energy function and the different neighboring atomic shells are also determined on the total stress in the system. The model results show that the sixth nearest neighboring shell has the greatest effect on the stress-strain curve of the Ni–Al single crystal. The associated calculations in the model also show that, in the absence of the pair interaction type of the sixth nearest neighboring shell, the behavior of the material approaches a linear elastic one.

A combinatory topological analysis and simulation of the self-assembly of the crystal structure of Ca11Hg54–hP65 (a = b = 17.114 A, c = 10.442 A, hexagonal group P-6) are performed by computer methods (ToposPro software package). A total of 184 variants of the cluster representation of the 3D atomic lattice with a number of structural units of 3–7 are established. The polyhedral clusters K8 = 0@Ca2Hg6, which appeared to be hexagonal bipyramids, the polyhedral clusters K11 = 0@Ca3Hg8, and the polyhedral clusters with the central Hg atom K12 = Hg(Ca3Hg8) are determined. The centers of the Ca2Hg6, 0@Ca3Hg8 and Hg(Ca3Hg8) clusters occupied the highly symmetric positions 1c, 1b, and 1f with a –6 symmetry. The precursor clusters Ca2Hg6 represent templates on the surface of which atomic shells of 38 atoms are formed. The composition of the two-layered template cluster K46 is 0@8(Ca2Hg6)@38(Hg6 + CaHg6)2(Ca6Hg6). The symmetry and topological code for the self-assembly processes of the 3D structure from the nanoclusters-precursors K46 with participation of the polyhedral clusters 0@Ca3Hg8 and Hg(Ca3Hg8) are simulated.

Gas-phase near-edge X-ray-absorption fine structure (NEXAFS) action spectroscopy around the oxygen K-edge and mass spectrometry were employed to probe isolated substance P (SP) molecular ions, both bare and progressively solvated with 4 and 11 water molecules. Detailed mass spectra of bare and hydrated precursors are presented for the resonant photon energy of 532 eV that corresponds to O1s --> pi(amide)* core excitation, triggering resonant Auger decay and fragmentation from the ionized radical molecular system. The fragmentation pattern of doubly protonated SP hydrated with 4 water molecules clearly shows a series of abundant doubly charged backbone fragments, as well as triply charged precursor with small neutral losses, all preserving full water cluster. This is drastically different from the collisional induced dissociation of the hydrated peptide where the water loss is a dominant relaxation process. Moreover, the action NEXAFS obtained from several resolved small backbone fragments revealed increased fragmentation of hydrated SP relative to the bare one, due to a resonant O1s excitation of the attached water molecules. Such unexpected result inspires further experimental developments to investigate possible nonlocal energy transfer from the solvent to the biomolecules within the first solvation shell. The experiment is supported by molecular dynamics and DFT calculations to estimate the intensity of the resonant X-ray absorption of bare and hydrated SP around peptide and water O1s excitation region.

The effect of f–d interaction on the current–voltage characteristics of metal–dielectric–metal (MDM) structures consisting of contacting layers of d metals (Fe, Co, Ni) and rare-earth metal (REM) oxides is studied. The f–d exchange interaction between atoms with unfilled f and d electron shells in the thin-film (Fe, Co, Ni)/Tb2O3/(Fe, Co, Ni) MDM structure significantly decreases the potential barrier to transfer of charges between the electrodes. The force and energy of f–d interaction that influence the movement of an electron in the MDM structure have been determined in conditions of the overbarrier charge transfer mechanism. The effect of f–d interaction on the current–voltage characteristics of MDM structures weakens with higher temperature and enhances with stronger magnetic field. This may be associated with the influence of these factors on the ordering of magnetic moments of f and d atoms in the f–d interaction region.

The electron density distribution in solid solutions between the high-temperature (cubic) phases of copper and silver chalcogenides has been assessed within the density-functional approach using pseudopotential calculations implemented in the Quantum Espresso program package. The results indicate that Cu–Ag cation substitutions and S–Se–Te anion substitutions lead to a reduction in electron shell overlap.

Studies of K-shell plasma radiation sources were performed on the GIT-12 generator (4.7 MA, 1.7 μs). In the experiments, a new type of load configuration was used to form the Z-pinch plasma – a gas puff with an outer plasma shell. Noble gases neon and argon were used as working gases. The gas puff consisted of two cascades: a hollow cylindrical shell outside and a solid jet inside. The outer plasma shell was created with the help of plasma guns located on a diameter of 350 mm. A distinctive feature of these studies is that the experiments with the plasma radiation source were carried out in the microsecond implosion regime usually leading to a significant decrease in the efficiency of generation of K-shell x-rays. The use of the Z-pinch load of a new type significantly improved the efficiency of the microsecond plasma radiation source. As a result of optimization of the initial gas-puff parameters, a neon K-shell radiation yield of 14.7 kJ/cm at a peak implosion current of 3.5 MA was achieved. In experiments with argon gas puffs, the radiation yield reached 1.9 kJ/cm at a peak implosion current of 3.1 MA.

Using computer methods (the ToposPro software package), the combinatorial-topological analysis and modeling of the self-assembly of the K23Na8Cd12In48–hP91(a = b = 17.114 A, c = 10.442 A, group P6/mmm) crystal structure are carried out. The chemically different precursor clusters 0@8(Na2In6) and 0@K2In6 in the form of hexagonal bipyramids are established. The centers of Na2In6 clusters occupy positions 1a with a symmetry of 6/mmm. The centers of the K2In6–A and K2In6–B clusters occupy positions 2c with symmetry –6m2, and 3g positions with mmm symmetry. The Na2In6 clusters are the templates on the surface of which atomic shells of 36 atoms are formed. The composition of the two-layer cluster is K44 = 0@8(Na2In6)@36(In6Cd6K6)2. Layer formation occurs upon the K44 clusters binding to the K2Cd6–A clusters. The symmetry and topological code of the self-assembly of the 3D structures from the K44 suprapolyhedral precursors with the participation of the K2Cd6 polyhedral clusters, as well as Na and K spacer atoms, are reconstructed.

Acoes Integradas Luso-Francesas, Acao Ref. TC08-17; Programa Pessoa 2017-2018; EMPIR, Grant/Award Number: 17FUN02 MetroMMC; FCT (Portugal), Grant/Award: SFRH/BPD/94234/2013; FCT, Grant/Award Number: PTDC/FIS-AQM/31969/2017. Zinc K-shell radiative and radiationless transition rates are calculated using the multiconfiguration Dirac–Fock method. Correlation up to the 4p orbital is included in almost all transition rate calculations. Calculated radiative transition rates and transition probabilities are compared with Scofield's Dirac–Hartree–Slater and Dirac–Hartree–Fock calculations, presenting good agreement with the later. Radiative transition intensity ratios involving the strongest lines are compared with theoretical, experimental, and empirical-fit values. Most ratios are in close agreement with the empirical-fit values from NIST's Fundamental Parameters database. Calculated radiationless transition rates and ratios are compared with Chen et al.'s Dirac–Fock values and Safronova et al.'s Dirac–Fock values. The K-LL transition rates are overall lower than Chen et al.'s values, whereas the K-LX and K-XY transition rates are overall higher. Calculated K-LX/K-LL and K-XY/K-LL ratios are relatively close to the experimental values compared. Some calculated intensities relative to K-L2(1D2) are in good agreement with the experimental values, whereas others present worse agreement. The calculated fluorescence yield is higher than all theoretical, experimental, and empirical-fitted values compared, probably because the total radiationless transition rate value calculated in the present work is relatively low. publishersversion published

A dynamic matrix of rare-gas crystals is constructed within the model of deformable and polarizable atoms based on the nonempirical short-range repulsion potential taking into account the three-body interaction and deformation of electron shells of dipole-type atoms within the pair and three-body approximations. Ab initio calculations of the phonon energy for compressed rare-gas crystals are performed at two and ten mean-value points of the Chadi–Kohen method in a wide pressure range. It is shown that the contribution of three-body forces to the phonon frequencies due to overlap of electron shells of neighboring atoms is small as compared to the pair interaction even at a high pressure and most pronounced for Xe. The contributions of the deformation of electron shells within the pair and three-body approximations differ for different mean-value points and increase with an increase in pressure. The zero-point energies calculated by the Chadi–Kohen method for crystals of the Ne–Xe series are compared with the known experimental data at p = 0 and calculation results obtained by other researchers.

After a compact history of the PT, from Döbereiner’s triads to the theoretical predictions up to element 172, a number of particular issues is discussed: Why may Z = 172 be a limit for stable electron shells? What are the expected stability limits of the nuclear isotopes? When are formally empty atomic orbitals used in molecular electronic structures? What is ‘Secondary Periodicity’? When do the elements (Ir, Pt, Au), at the end of a bond, simulate (N, O, I), respectively? Some new suggestions for alternative PTs are commented upon. As a local connection, Johan Gadolin’s 1794 analysis of the Ytterby mineral is mentioned.

The combinatoric and topological analysis and modeling of the self-assembly of the Na26Cd141–hP168 crystal structure (space group Pbcm; a = 5.483 A, b = 24.519 A, and c = 14.573 A; and V = 1895 A3) are performed using computational methods (the ToposPro software package). Ninety-eight versions of the cluster representation of the 3D atomic network with the number of structural units ranging from four to seven are found. It is determined that polyhedral clusters–precursors C8 = 0@Na2Cd6 and C9 = 0@Na3Cd6 are templates, on the surface of which atomic shells consisting of 38 and 41 atoms are formed. The composition of the two-layer clusters is C46 = 0@(Na2Cd6)@(Na12Cd26) and C50 = 0@(Na3Cd6)@(Na6Cd35). The centers of clusters C46 and C50 are occupied by positions 1a with the symmetry 6/mmm and 2c with the symmetry −6m2. The symmetry and topology codes of the processes of self-assembly of 3D structures from nanoclusters–precursors C46 and C50 are reconstructed.

The spectroscopic parameters of the BeH and CH molecules with an open electron shell are calculated in the basis of the Slater functions. An analytical expression for the total electron energy of molecules with an open electron shell is obtained. The total electron energy of the BeH and CH molecules was calculated by the Hartree–Fock–Roothaan (HFR) method for seven internuclear distances, including the equilibrium internuclear distance. A table of total energy values is constructed depending on the internuclear distance R. The total energy of a diatomic molecule is approximated as a third-degree polynomial in R. Applying the least squares method to energy values from the above-mentioned table, an analytical formula for the total energy of the BeH and CH molecules is obtained as a function of R. The analytical formula for E(R) has allowed the spectroscopic parameters ωe (harmonic vibrational frequency), ωexe (anharmonicity constant), Be (rotational constant), and αe (rovibrational interaction constant) to be calculated.

WOS: 000477168500001, In this study, K-alpha 1,K-2, K-beta 1,K-3, and K-beta 2,K-4 X-ray natural line widths for various elements were determined semi-empirically at 123.6 keV by using K shell fluorescence yields obtained from energy dispersive X-ray fluorescence measurements. The obtained results contribute to a database for the development of new theoretical models of atomic structure, radiation shielding materials, and designing new technological devices related to the structural analysis of materials. The obtained results were compared with the literature, while new fitting polynomials for the studied parameters were acquired. The results showed that the natural linewidths of K X-ray lines fit fourth-order polynomials except for K-beta 2,K-4.

The double K-shell ionization of Sc, Cr and Cu induced by electron impact was investigated via high energy resolution measurements of the Kα diagram transitions and the transitions resulting from the radiative decay of K-shell double vacancy states, namely the Khα hypersatellites. For Sc, the Kβ diagram lines and Khβ hypersatellites were also measured. The measurements were carried out in-house with a von Hamos curved crystal spectrometer operated in the so-called direct geometry in which the anodes of Sc, Cr and Cu X-ray tubes were used as targets. For each element, the electron kinetic energy was chosen to be about twice the threshold energy for the double 1s ionization. The double-to-single ionization cross-sections ratios PKK were deduced from the hypersatellite-to-diagram line yield ratios, corrected beforehand for the self-absorption of the X-rays in the target and the energy dependent efficiency of the spectrometer. The obtained ratios are discussed and compared to other PKK values found in the literature for electrons and photons.

The wavelengths and rates of single- and double-electron transitions leading to the emission of a single photon between 2s3s and nsn′p (n = 1, 2 and n′ = 2–4) groups in He-like ions with empty K shell have been studied for 15 ions in the range 13 ≤ Z ≤ 54 using fully relativistic multi-configuration Dirac–Fock wavefunctions in the active space approximation. The complete relaxation of atomic orbitals and most important configuration interaction effects have been taken into account. The variations in the admixture of the correlation functions coupled with Breit interaction responsible for the sudden changes in the line intensities of certain transitions from 2s3s have been discussed in detail. The radiative rates of the electric dipole transitions have been evaluated as accurately as possible by taking into account all the non-negligible contributions to the X-ray rates. The Auger rates have been calculated using a scaling procedure on the already existing relativistic radial matrix elements for an initial K hole atom. The present results are compared with other available theoretical data. The computed data can be conveniently used in the analysis of experimental spectra and in the measurements of X-ray fluorescence yields for the doubly excited states under study.

A zero dimensional thin-shell implosion model with a coupled equivalent circuit for the description of an imploding nested wire array or gas puff is presented. Model results have been compared with data from imploding stainless-steel wire arrays and good agreement has been found.