Atoms

13 pages, 375 KiB

Open AccessArticle

by Savinder Kaur, Ajay Kumar Arora, Kasturi Lal Baluja and Anand Bharadvaja

Atoms 2025, 13(4), 29; https://doi.org/10.3390/atoms13040029 - 1 Apr 2025

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Various electron impact scattering cross sections of Sevoflurane are reported up to 5 keV. The elastic cross sections (differential and integral) are computed using the single-centre-expansion formalism within a molecular framework. The ground state target wavefunction is determined at the Hartree–Fock (HF) level. Post-HF corrections are incorporated to make a scattering realistic model. The total interacting potential is defined as the sum of static, correlation–polarization and exchange potentials. These potentials are numerically computed using their local forms. The long-range effects affecting the scattering due to the polar nature of the molecule are incorporated using the Born Top-up approach. The ionization cross sections are obtained from the semi-empirical binary-encounter-Bethe model. The total cross sections are estimated from the incoherent sum of Born-corrected elastic integral and ionization cross sections. The computed results show fairly good agreement with the experimental reported cross sections. Full article

(This article belongs to the Special Issue Many-Particle Dynamics in Collisions of Electrons, Positrons and Photons, 2nd Edition)

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13 pages, 2840 KiB

Open AccessArticle

Electron Spin Resonance Study on Hydrogen Abstraction Reactions of Radiation-Induced Radicals in Synthetic Silica Clathrate with Ethylamine and Ethanol

by Shusuke Isogai, Kazuhiko Masuda, Kazuma Dan, Atsushi Tani and Sachiko Tojo

Atoms 2025, 13(4), 28; https://doi.org/10.3390/atoms13040028 - 31 Mar 2025

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Abstract

Intermolecular hydrogen abstraction reactions of radiation-induced radicals from guest molecules in adjacent cages, as observed in clathrate hydrates, were investigated in synthetic silica clathrate (clathrasil) with ethylamine and ethanol. ESR observation of the silica clathrate after γ-ray irradiation at 77 K confirmed the formation of 1-aminoethyl radical (CH₃)(CH·)(NH₂), 1-hydroxyethyl radical (CH₃)(CH·)(OH), and hydrogen atom at 225 K. In isothermal annealing experiments, the amount of hydrogen atoms decreased at around 225 K following first-order kinetics, while the amount of 1-aminoethyl radical simultaneously increased by a similar amount. The amount of 1-hydroxyethyl radical decreased at temperatures around 280 K with first-order kinetics, while the amount of 1-aminoethyl radical increased at these temperatures. These results suggest that hydrogen abstraction reactions occur not only between the hydrogen atom and ethylamine at around 225 K but may also occur between 1-hydroxyethyl radical and ethylamine at around 280 K. Furthermore, observation of 1-hydroxyethyl radical in silica clathrate with only a small amount of ethanol indicated that ESR measurements could be used to detect traces of guest molecules in clathrates if the radicals derived from them are stably stored in the cages. Full article

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

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5 pages, 278 KiB

Open AccessArticle

Benchmark Calculations for Near-Threshold Electron-Impact Excitation of the (1s3s)^3,1S States of Helium

by Klaus Bartschat, Igor Bray and Dmitry V. Fursa

Atoms 2025, 13(4), 27; https://doi.org/10.3390/atoms13040027 - 31 Mar 2025

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Abstract

We revisit the current status of high-precision calculations for electron-impact excitation of the

{(1 s 3 s)}^{3, 1} S

states in helium in the low-energy near-threshold regime that is characterized by a large number of resonance features. Having noticed [...] Read more.

We revisit the current status of high-precision calculations for electron-impact excitation of the

{(1 s 3 s)}^{3, 1} S

states in helium in the low-energy near-threshold regime that is characterized by a large number of resonance features. Having noticed discrepancies between predictions from two previous large-scale calculations for this problem, we report new results and make recommendations regarding the absolute cross-sections that should be used in modeling applications. Full article

(This article belongs to the Special Issue Ab Initio Calculations in Atomic, Molecular, and Optical Physics: A Tribute to Barry Irwin Schneider)

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11 pages, 2964 KiB

Open AccessArticle

Spatially Resolved Precision Measurement of Magnetic Field Using Ultracold Cesium Atoms as Sensors

by Anjali Bisht, Manoj Das and Poonam Arora

Atoms 2025, 13(4), 26; https://doi.org/10.3390/atoms13040026 - 27 Mar 2025

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Abstract

Sub-Doppler laser-cooled cesium-133 atoms are utilized as quantum sensors to achieve precise mapping of magnetic fields across a region in ultra-high vacuum (UHV), with a spatial resolution of 1 cm and a sensitivity of approximately 550 pT/√Hz, enabling accurate measurements within the nanotesla [nT] range. The cold cesium-133 atoms used for magnetic field measurements in this paper are a key component of the cesium fountain frequency standard at CSIR-NPL, which contributes to both timekeeping and magnetic sensing. The results show magnetic field fluctuations within 1 nT with a spatial resolution of 1 cm. The uncertainty in these measurements is of the order of 1.24 × 10⁻¹⁶, ensuring reliable and precise spatially resolved magnetic field mapping. Full article

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26 pages, 414 KiB

Open AccessArticle

Statistics of Quantum Numbers for Non-Equivalent Fermions in Single-j Shells

by Jean-Christophe Pain

Atoms 2025, 13(4), 25; https://doi.org/10.3390/atoms13040025 - 25 Mar 2025

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Abstract

This work addresses closed-form expressions for the distributions

P (M)

of the magnetic quantum numbers M and

Q (J)

of total angular momentum J for non-equivalent fermions in single-j orbits. Such quantities play an important role in both [...] Read more.

This work addresses closed-form expressions for the distributions

P (M)

of the magnetic quantum numbers M and

Q (J)

of total angular momentum J for non-equivalent fermions in single-j orbits. Such quantities play an important role in both nuclear and atomic physics, through the shell models. Using irreducible representations of the rotation group, different kinds of formulas are presented, involving multinomial coefficients, generalized Pascal triangle coefficients, or hypergeometric functions. Special cases are discussed, and the connections between

P (M)

(and therefore

Q (J)

) and mathematical functions such as elementary symmetric, cyclotomic, and Jacobi polynomials are outlined. Full article

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

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Atoms, Volume 13, Issue 4 (April 2025) – 5 articles

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