Atoms

16 pages, 1396 KiB

Open AccessArticle

EWS Time Delay in Low Energy e−C₆₀ Elastic Scattering

by Aiswarya R., Rasheed Shaik, Jobin Jose, Hari R. Varma and Himadri S. Chakraborty

Atoms 2024, 12(3), 18; https://doi.org/10.3390/atoms12030018 - 21 Mar 2024

Cited by 1 | Viewed by 1584

Access to time delay in a projectile-target scattering is a fundamental tool in understanding their interactions by probing the temporal domain. The present study focuses on computing and analyzing the Eisenbud-Wigner-Smith (EWS) time delay in low energy elastic

e - C_{60}

scattering. [...] Read more.

Access to time delay in a projectile-target scattering is a fundamental tool in understanding their interactions by probing the temporal domain. The present study focuses on computing and analyzing the Eisenbud-Wigner-Smith (EWS) time delay in low energy elastic

e - C_{60}

scattering. The investigation is carried out in the framework of a non-relativistic partial wave analysis (PWA) technique. The projectile-target interaction is described in (i) Density Functional Theory (DFT) and (ii) Annular Square Well (ASW) static model, and their final results are compared in details. The impact of polarization on resonant and non-resonant time delay is also investigated. Full article

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

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8 pages, 392 KiB

Open AccessCommunication

General Aspects of Line Shapes in Plasmas in the Presence of External Electric Fields

by Spiros Alexiou

Atoms 2024, 12(3), 17; https://doi.org/10.3390/atoms12030017 - 15 Mar 2024

Viewed by 1263

Abstract

The present paper discusses a number of topics relevant to line broadening in the presence of periodic oscillatory fields. Specifically, we discuss the applicablility of the expression usually employed to compute the autocorrelation function, the dressing, accounting for random phases, neglecting fine structure [...] Read more.

The present paper discusses a number of topics relevant to line broadening in the presence of periodic oscillatory fields. Specifically, we discuss the applicablility of the expression usually employed to compute the autocorrelation function, the dressing, accounting for random phases, neglecting fine structure and numerical issues associated with stiffnes. Full article

(This article belongs to the Special Issue Plasma Spectroscopy and Plasma Diagnostics: From Classical to Sophisticated Methods)

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11 pages, 2109 KiB

Open AccessArticle

Simulation of Extreme Ultraviolet Radiation and Conversion Efficiency of Lithium Plasma in a Wide Range of Plasma Situations

by Xiangdong Li, Frank B. Rosmej and Zhanbin Chen

Atoms 2024, 12(3), 16; https://doi.org/10.3390/atoms12030016 - 12 Mar 2024

Viewed by 1594

Abstract

Based on the detailed term accounting approach, the relationship between extreme ultraviolet conversion efficiency and plasma conditions, which range from 5 to 200 eV for plasma temperature and from 4.63 × 10¹⁷ to 4.63 × 10²² cm⁻³ for plasma density, [...] Read more.

Based on the detailed term accounting approach, the relationship between extreme ultraviolet conversion efficiency and plasma conditions, which range from 5 to 200 eV for plasma temperature and from 4.63 × 10¹⁷ to 4.63 × 10²² cm⁻³ for plasma density, is studied for lithium plasmas through spectral simulations involving very extended atomic configurations, including a benchmark set of autoionizing states. The theoretical limit of the EUV conversion efficiency and its dependence on sustained plasma time are given for different plasma densities. The present study provides the necessary understanding of EUV formation from the perspective of atomic physics and also provides useful knowledge for improving EUV conversion efficiency with different technologies. Full article

(This article belongs to the Special Issue Atomic Physics in Dense Plasmas)

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10 pages, 451 KiB

Open AccessBrief Report

Continuous Acceleration Sensing Using Optomechanical Droplets

by Gordon R. M. Robb, Josh G. Walker, Gian-Luca Oppo and Thorsten Ackemann

Atoms 2024, 12(3), 15; https://doi.org/10.3390/atoms12030015 - 6 Mar 2024

Viewed by 1678

Abstract

We show that a Bose–Einstein Condensate illuminated by a far off-resonant optical pump field and its retroreflection from a feedback mirror can produce stable, localised structures known as optomechanical droplets. We show that these droplets could be used to measure the acceleration of [...] Read more.

We show that a Bose–Einstein Condensate illuminated by a far off-resonant optical pump field and its retroreflection from a feedback mirror can produce stable, localised structures known as optomechanical droplets. We show that these droplets could be used to measure the acceleration of a BEC via continuous monitoring of the position of the droplet via the optical intensity distribution. Full article

(This article belongs to the Special Issue Cold and Rydberg Atoms for Quantum Technologies)

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19 pages, 551 KiB

Open AccessArticle

Prospective Optical Lattice Clocks in Neutral Atoms with Hyperfine Structure

by Tobias Bothwell

Atoms 2024, 12(3), 14; https://doi.org/10.3390/atoms12030014 - 5 Mar 2024

Viewed by 1811

Abstract

Optical lattice clocks combine the accuracy and stability required for next-generation frequency standards. At the heart of these clocks are carefully engineered optical lattices tuned to a wavelength where the differential AC Stark shift between ground and excited states vanishes—the so called ‘magic’ [...] Read more.

Optical lattice clocks combine the accuracy and stability required for next-generation frequency standards. At the heart of these clocks are carefully engineered optical lattices tuned to a wavelength where the differential AC Stark shift between ground and excited states vanishes—the so called ‘magic’ wavelength. To date, only alkaline-earth-like atoms utilizing clock transitions with total electronic angular momentum

J = 0

have successfully realized these magic wavelength optical lattices at the level necessary for state-of-the-art clock operation. In this article, we discuss two additional types of clock transitions utilizing states with

J \neq 0

, leveraging hyperfine structure to satisfy the necessary requirements for controlling lattice-induced light shifts. We propose realizing (i) clock transitions between same-parity clock states with total angular momentum

F = 0

and (ii) M1/E2 clock transitions between a state with

F = 0

and a second state with

J = 1 / 2

,

m_{F} = 0

. We present atomic species which fulfill these requirements before giving a detailed discussion of both manganese and copper, demonstrating how these transitions provide the necessary suppression of fine structure-induced vector and tensor lattice light shifts for clock operations. Such realization of alternative optical lattice clocks promises to provide a rich variety of new atomic species for neutral atom clock operation, with applications from many-body physics to searches for new physics. Full article

(This article belongs to the Special Issue High-Precision Laser Spectroscopy)

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23 pages, 366 KiB

Open AccessArticle

Energy Levels and Transition Data of Cs VI

by Abid Husain, Haris Kunari and Tauheed Ahmad

Atoms 2024, 12(3), 13; https://doi.org/10.3390/atoms12030013 - 27 Feb 2024

Viewed by 1564

Abstract

Previously reported atomic data (spectral lines, wavelengths, energy levels, and transition probabilities) were collected and systematically analyzed for Cs VI. The present theoretical analysis was supported by extensive calculations made for Cs VI with a pseudo-relativistic Hartree–Fock (HFR) method together with the superposition [...] Read more.

Previously reported atomic data (spectral lines, wavelengths, energy levels, and transition probabilities) were collected and systematically analyzed for Cs VI. The present theoretical analysis was supported by extensive calculations made for Cs VI with a pseudo-relativistic Hartree–Fock (HFR) method together with the superposition of configuration interactions implemented in Cowan’s codes. In this work, all previously reported energy levels and their (allowed) transition assignments were confirmed. A critically evaluated set of optimized energy levels with their uncertainties, observed and Ritz wavelengths along with their uncertainties, and theoretical transition probabilities with their estimated uncertainties were presented in the compilation. In addition to this, we determined the radiative transition parameters for several forbidden lines within the ground configuration

5 s^{2} 5 p^{2}

of Cs VI. Full article

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30 pages, 1083 KiB

Open AccessTutorial

Long-Lived Levels in Multiply and Highly Charged Ions

by Elmar Träbert

Atoms 2024, 12(3), 12; https://doi.org/10.3390/atoms12030012 - 23 Feb 2024

Viewed by 1766

Abstract

Atoms and ions remain in some long-lived excited levels for much longer than in typical “normal” levels, but not forever. Various cases of this so-called metastability that occur in multiply or even highly charged ions are discussed in a tutorial review, as well [...] Read more.

Atoms and ions remain in some long-lived excited levels for much longer than in typical “normal” levels, but not forever. Various cases of this so-called metastability that occur in multiply or even highly charged ions are discussed in a tutorial review, as well as examples of atomic lifetime measurements on such levels, their intentions, and some present and future applications. Full article

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

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Atoms, Volume 12, Issue 3 (March 2024) – 7 articles

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