The European Physical Journal D最新文献

In this study, we conduct atomistic-level molecular dynamics simulations on fixed-sized silicon-germanium (Si(_{1-x})Ge(_{x})) crystals to elucidate the effects of dopant concentration on the crystalline inter-planar distances. Our calculations consider a range of Ge dopant concentrations between pure Si (0%) and 15%, and for both the optimised system state and a temperature of 300K. We observe a linear relationship between Ge concentration and inter-planar distance and lattice constant, in line with the approximation of Vegard’s Law, and other experimental and computational results. These findings will be employed in conjunction with future studies to establish precise tolerances for use in crystal growth, crucial for the manufacture of crystals intended for emerging gamma-ray crystal-based light source technologies.

Atomic cascades refer—first and foremost—to the stepwise de-excitation of excited atoms owing to the emission of electrons or photons. Apart from dedicated experiments at storage rings and synchrotrons, such cascades frequently occur in astro and plasma physics, material research, surface science and at various places elsewhere. In addition, moreover, “atomic cascades” have been found a useful concept for modeling atomic behavior under different conditions, for instance, when dealing with the photoabsorption of matter, the generation of synthesized spectra, or for determining a rather wide class of (plasma) rate coefficients. We here compile and discuss several atomic cascades (schemes) that help predict cross sections, rate coefficients, electron and photon spectra, or ion distributions. We also demonstrate how readily these schemes have been implemented within JAC, the Jena Atomic Calculator. Emphasis is placed on the classification of atomic cascades and their (quite) natural breakdown into cascade computations, to deal with the electronic structure and transition amplitudes of atoms and ions, as well as the cascade simulation of those properties and spectra, that are experimentally accessible. As an example, we show and discuss the computation of dielectronic recombination plasma rate coefficients for beryllium-like gold ions. The concept of atomic cascades and its implementation into JAC can be applied for most ions across the periodic table and will facilitate the modeling and interpretation of many forthcoming observations.

This work describes the tests performed with a newly built hollow-cathode lamp to ensure its capability to measure atomic parameters such as transition probabilities accurately. We discuss the design of the lamp and the experimental setup that will be used to measure transition probabilities. We show the discharge characteristics of the lamp and also the stability of spectral emission of the lamp over a period of two hours. Finally, it is concluded that the experimental setup, the lamp, and a camera with high resolving power are well suited for the measurement of the transition probabilities of doubly ionised rare-earths like Nd III.

Graphical abstract illustrating the use of a hollow-cathode lamp setup for accurately measuring branching fractions of rare-earth elements. The setup includes a diffraction grating spectrometer and a CMOS camera to detect radiation across a spectral range of 200 nm to 800 nm with a resolving power of 150,000 at 450 nm

In this paper, we present a detailed analytical computation of the triple differential cross section, in the first Born approximation, for the relativistic electron-impact ionization of the metastable atomic hydrogen H(2S) in the symmetric coplanar geometry and in the presence of a circularly polarized laser field. We introduce as a first step the Dirac–Volkov plane wave Born approximation 1 where we take into account only the relativistic dressing of the incident and scattered electrons. Then, we introduce the Dirac–Volkov plane wave Born approximation 2 where we take totally into account the relativistic dressing of the incident, scattered and ejected electrons. This paper is an extension of the previous one (Jakha et al. in Chin J Phys 77:1048, 2022), where we studied the same process in the absence of any external field. The combination of these two complementary works can provide a thorough and comprehensive study that can pave the way for any future experimental investigation.

It is shown that the masking process will be implemented successfully if the targeted masked qubit evolves by Hermitian or non-Hermitian energy operators. For a two-qubit system, we showed that a single ancillary (blank). A single qubit is sufficient to mask the encoded information in this two-qubit system. Similarly, the process can be performed if the initial qubits system evolves by Hermitian or non-Hermitian energy operator.

In this work, we study an electron subjected to a harmonic oscillator potential confined in a circle of radius (r_0) and in the presence of a constant electric field. We obtain energies and eigenfunctions for three different confinement radii as a function of the electric field strength. We have used the linear variational method by constructing the trial function as a linear combination of two-dimensional confined harmonic oscillator wave functions. We calculate the radial standard deviation as a measure of the dispersion of the probability density. We also computed the Shannon entropy and Fisher information, in configuration and momentum spaces, as localization-delocalization measures for three different confinement radii and as a function of the electric field strength. We find that Shannon entropy and Fisher information are more reliable than variance in determining electron location. The behaviour of Shannon entropy and Fisher information curves is shown to depend on each specific state under study.

An asymmetric graphene nanoribbon structure is presented to reach plasmonic Fano resonance in mid-infrared region when illuminated by a TM polarized light. Each mode of the Fano resonance is connected to the resonance mode occurred around each of nanoribbons with different width in the structure. Numerical studies show that the position and amplitude of the double resonances can be actively adapted via geometrical modification of the graphene structure or altering the doping level. Moreover, simulation results show highly remarkable enhancement in normalized electric field intensity for the asymmetric graphene structure compared to its symmetric counterparts. This feature is advantageous for construction of high sensitivity instruments such as sensors or filters.

Laser spectroscopy is a very precise tool in determining atomic structure data. However, in the case of complex spectra, when the individual components of the spectra cannot be separated, precise analysis is hindered by the appearing saturation effect. Sometimes this effect is so large that the spectrum simulation does not provide precise results. In the present work, we present the analysis of the Zeeman spectra of seven praseodymium lines in the range of 566–652 nm, which were recorded using the LIF technique in the presence of the saturation effect. To analyze these spectra, we used a specially dedicated computer program, which allowed for very accurate matching of the simulated spectrum to the recorded experimental shape. As a result of the conducted research, we determined 14 Lande factor values, 3 of which are new.

We present new experimental and theoretical cross sections for electron-impact single ionization of Xe(^{12+}) and Xe(^{13+}) ions, and double ionization of Xe(^{12+}), Xe(^{13+}) and Xe(^{14+}) ions for collision energies from the respective ionization thresholds up to 3500 eV. The calculations use the fully relativistic subconfiguration-averaged distorted-wave approach and, partly, the more detailed level-to-level distorted wave method. We find that, unlike in previous work, our theoretical cross sections agree with our experimental ones within the experimental uncertainties, except for the near-threshold double-ionization cross sections. We attribute this remaining discrepancy to the neglect of direct-double ionization in the present theoretical treatment.

Experimental and theoretical cross sections for electron-impact single ionization of Xe(^{12+}).