Atoms

12 pages, 1059 KiB

Open AccessArticle

The Influence of External Radiation on the Emission Properties of H- and He-like Argon Ions in High Temperature Plasma

by Roman K. Kulikov, Igor Yu. Skobelev and Evgeny D. Filippov

Atoms 2025, 13(6), 51; https://doi.org/10.3390/atoms13060051 - 11 Jun 2025

In the present work, the influence of external X-ray radiation on the kinetics of multicharged ions in high-temperature plasma is investigated. A generalized diagnostic approach is proposed for the electron density and temperature measurements of photo-pumped plasma based on the relative intensity of the H-like ion resonance line and its dielectronic satellites. Based on detailed kinetic calculations performed for argon plasma, the conditions under which these techniques can be applied without modification to the photo-pumped plasma are determined, and the relative intensities of these lines are calculated for cases where the external influence significantly alters the kinetics of their excitation. The development of such diagnostic methods is of particular importance for the experiments with powerful X-ray free-electron lasers and thermonuclear laser plasma. Full article

(This article belongs to the Special Issue Atom and Plasma Spectroscopy)

1 pages, 128 KiB

Open AccessCorrection

Correction: Nishimura et al. Charge Exchange Spectroscopy of Multiply Charged Erbium Ions. Atoms 2023, 11, 40

by Yuki Nishimura, Saki Imaizumi, Hajime Tanuma, Nobuyuki Nakamura, Yuichiro Sekiguchi, Shinya Wanajo, Hiroyuki A. Sakaue, Daiji Kato, Izumi Murakami, Masaomi Tanaka and Gediminas Gaigalas

Atoms 2025, 13(6), 50; https://doi.org/10.3390/atoms13060050 - 9 Jun 2025

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Abstract

The journal’s Editorial Office and Editorial Board are jointly issuing a resolution and removal of the Journal Notice linked to this article [...] Full article

10 pages, 509 KiB

Open AccessArticle

Energy Levels, Lifetimes, and Transition Properties for N iii – v

by Meichun Li, Juan Du, Kaijian Huang and Wenxian Li

Atoms 2025, 13(6), 49; https://doi.org/10.3390/atoms13060049 - 6 Jun 2025

Viewed by 140

Abstract

We present excitation energies, transition wavelengths, electric dipole (E1) transition rates, oscillator strengths, line strengths, and lifetimes for the 86 lowest states up to and including

1 s^{2} 2 s^{2} 7 f

in N iii, the 125 lowest states up [...] Read more.

We present excitation energies, transition wavelengths, electric dipole (E1) transition rates, oscillator strengths, line strengths, and lifetimes for the 86 lowest states up to and including

1 s^{2} 2 s^{2} 7 f

in N iii, the 125 lowest states up to and including

1 s^{2} 2 s 7 f

in N iv, and the 53 lowest states up to

1 s^{2} 8 g

in N v using the multiconfiguration Dirac–Hartree–Fock (MCDHF) and relativistic configuration interaction (RCI) methods. The computed results are then compared with data from the Atomic Spectra Database of the National Institute of Standards and Technology (NIST-ASD), experimental results, and other theoretical studies. For all levels in N iii – v, the root mean square energy differences from the NIST values are 130, 103, and 6 cm⁻¹, respectively. Compared to previous multiconfiguration Hartree–Fock and the Breit–Pauli (MCHF-BP) calculations, 89.3%, 98.5%, and 100% of the

log (g f)

values for N iii – v agree within 5%, respectively. Full article

(This article belongs to the Special Issue Atomic and Molecular Data and Their Applications: ICAMDATA 2024)

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13 pages, 1934 KiB

Open AccessArticle

Collision Kinematics for Fast Positron Impact Ionization of Argon

by Robert D. DuBois and Károly Tőkési

Atoms 2025, 13(6), 48; https://doi.org/10.3390/atoms13060048 - 4 Jun 2025

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Abstract

Classical trajectory Monte Carlo calculations for 1 keV positron impact ionization of argon are presented. A combination of energy-weighted triple differential cross-sections is shown to provide good to excellent agreement compared with experimental data, depending on the ejected electron azimuthal angular acceptance range used to define in-plane scattering. For ejected electron energies less than 100 eV, information about the influence of pre- (the impact parameter) and post-(the direction of scattering) collision kinematics on the triple differential level is obtained. An overall picture of these kinematic properties is also presented for single differential cross-sections as a function of ejected electron energy and ejection angle. Full article

(This article belongs to the Section Atomic, Molecular and Nuclear Spectroscopy and Collisions)

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64 pages, 2080 KiB

Open AccessReview

Triaxial Shapes in Even–Even Nuclei: A Theoretical Overview

by Dennis Bonatsos, Andriana Martinou, Spyridon K. Peroulis, Dimitrios Petrellis, Polytimos Vasileiou, Theodoros J. Mertzimekis and Nikolay Minkov

Atoms 2025, 13(6), 47; https://doi.org/10.3390/atoms13060047 - 31 May 2025

Viewed by 157

Abstract

Triaxial shapes in even–even nuclei have been considered since the early days of the nuclear collective model. Although many theoretical approaches have been used over the years for their description, no effort appears to have been made for grouping them together and identifying regions on the nuclear chart where the appearance of triaxiality might be favored. In addition, over the last few years, discussion has started on the appearance of small triaxiality in nuclei considered so far as purely axial rotors. In the present work, we collect the predictions made by various theoretical approaches and show that pronounced triaxiality appears to be favored within specific stripes on the nuclear chart, with low triaxiality being present in the regions between these stripes, in agreement with parameter-free predictions made by the proxy-SU(3) approximation to the shell model, based on the Pauli principle and the short-range nature of the nucleon–nucleon interaction. The robustness of triaxiality within these stripes is supported by global calculations made in the framework of the Finite-Range Droplet Model (FRDM), which is based on completely different assumptions and possesses parameters fitted in order to reproduce fundamental nuclear properties. Full article

(This article belongs to the Section Nuclear Theory and Experiments)

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12 pages, 9743 KiB

Open AccessArticle

by Peter Van Reeth and John W. Humberston

Atoms 2025, 13(6), 46; https://doi.org/10.3390/atoms13060046 - 28 May 2025

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Abstract

Scattering differential cross-sections (DCSs) are important tools, both experimentally and theoretically, in the investigation of scattering processes in lepton–atom collisions. In the present work, the elastic scattering differential cross-sections (EDCSs) for e⁺-H and e⁺-He below the first excitation threshold of the target were evaluated using the Kohn variational method and found to be very similar. In both cases, the EDCS below the positronium formation threshold, i.e., for pure elastic scattering, had minimum valley features in which significant minima close to 90 degrees were found at ≈2.8 eV for H and ≈2 eV for He. These minima were shown to be linked to the zero in the s-wave phase shift, which gives rise to the Ramsauer minimum in the elastic integrated cross-sections. They were not vortices, but the overall EDCS structure was found to be related to the structures and vortices found in the Ps formation differential cross-sections just above the Ps formation threshold. The valley-type structure in the EDCS went smoothly through the Ps formation threshold, where it linked up with a similar valley structure in both the EDCS above the threshold and the Ps formation DCS. A comparison with the EDCS for e⁻-H and e⁻-He scattering over the same energy range revealed similarities with the positron EDCS, however, with less pronounced structures that had different angular and momentum dependences. Full article

(This article belongs to the Section Atomic, Molecular and Nuclear Spectroscopy and Collisions)

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Atoms, Volume 13, Issue 6 (June 2025) – 6 articles

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