Atoms

23 pages, 6236 KiB

Open AccessReview

A Study of the Atomic Processes of Highly Charged Ions Embedded in Dense Plasma

by Alok Kumar Singh Jha, Mayank Dimri, Dishu Dawra and Man Mohan

Atoms 2023, 11(12), 158; https://doi.org/10.3390/atoms11120158 - 15 Dec 2023

Cited by 3 | Viewed by 1989

The study of atomic spectroscopy and collision processes in a dense plasma environment has gained a considerable interest in the past few years due to its several applications in various branches of physics. The multiconfiguration Dirac-Fock (MCDF) method and relativistic configuration interaction (RCI) [...] Read more.

The study of atomic spectroscopy and collision processes in a dense plasma environment has gained a considerable interest in the past few years due to its several applications in various branches of physics. The multiconfiguration Dirac-Fock (MCDF) method and relativistic configuration interaction (RCI) technique incorporating the uniform electron gas model (UEGM) and analytical plasma screening (APS) potentials have been employed for characterizing the interactions among the charged particles in plasma. The bound and continuum state wavefunctions are determined using the aforementioned potentials within a relativistic Dirac-Coulomb atomic structure framework. The present approach is applied for the calculation of electronic structures, radiative properties, electron impact excitation cross sections and photoionization cross sections of many electron systems confined in a plasma environment. The present study not only extends our knowledge of the plasma-screening effect but also opens the door for the modelling and diagnostics of astrophysical and laboratory plasmas. Full article

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

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16 pages, 3558 KiB

Open AccessArticle

Reactions of CH₂OO, CH₃CHOO, and (CH₃)₂COO with Methane through the Formation of Intermediate Complex

by Yuri A. Dyakov, Sergey O. Adamson, Gennady V. Golubkov, Igor I. Morozov, Danil R. Nigmatullin, Oleg A. Olkhov, Pao K. Wang and Maxim G. Golubkov

Atoms 2023, 11(12), 157; https://doi.org/10.3390/atoms11120157 - 14 Dec 2023

Cited by 1 | Viewed by 1740

Abstract

Criegee intermediates, which are the products of the ozonolysis of alkenes, play a key role in many chemical and physical processes in the atmosphere. Their reactions with other atmospheric compounds are responsible for the formation of hydroxyl, methyl, hydrogen radicals, nitric and sulfuric [...] Read more.

Criegee intermediates, which are the products of the ozonolysis of alkenes, play a key role in many chemical and physical processes in the atmosphere. Their reactions with other atmospheric compounds are responsible for the formation of hydroxyl, methyl, hydrogen radicals, nitric and sulfuric acids, and others. Methane is an active greenhouse gas whose concentration has increased rapidly in the last several decades. In this work, we consider the interaction between these two important atmospheric compounds. We choose the three simple Criegee intermediate (CI) molecules: formaldehyde oxide (CH₂OO), acetaldehyde oxide (CH₃CHOO), and acetone oxide ((CH₃)₂COO). Some reactions between methane and these Cis have been studied earlier as possible pathways for deactivating methane as well as a source of methanol formation due to molecular collisions in the atmosphere. In the present study, we extend the consideration to the case when an intermediate energetically stable complex is formed after collision. We found that this complex could easily decompose to form an OH radical and another unstable fragment, which can quickly dissociate into CH₃ radicals, atomic hydrogen, acetone, acetaldehyde, propaldehyde, methyl alcohol, water, and others, depending on the type of CI being reacted with. These compounds can actively interact with other atmospheric components and change their physical and chemical properties. In addition, CI with a methyl substituent is shown to have increased energy in transition states and minima, resulting in slower reaction rates. Full article

(This article belongs to the Section Quantum Chemistry, Computational Chemistry and Molecular Physics)

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5 pages, 213 KiB

Open AccessEditorial

Photon and Particle Impact Spectroscopy and Dynamics of Atoms, Molecules and Clusters

by Himadri S. Chakraborty and Hari R. Varma

Atoms 2023, 11(12), 156; https://doi.org/10.3390/atoms11120156 - 12 Dec 2023

Cited by 1 | Viewed by 1484

Abstract

Atomic, molecular, and optical (AMO) physics is a vastly important sub-discipline [...] Full article

(This article belongs to the Special Issue Photon and Particle Impact Spectroscopy and Dynamics of Atoms, Molecules, and Clusters)

40 pages, 3865 KiB

Open AccessArticle

On Rayleigh–Taylor Dynamics

by Abdul Hasib Rahimyar, Des Hill, James Glimm and Snezhana Abarzhi

Atoms 2023, 11(12), 155; https://doi.org/10.3390/atoms11120155 - 8 Dec 2023

Viewed by 1658

Abstract

In this work, we theoretically and numerically investigate Rayleigh–Taylor dynamics with constant acceleration. On the side of theory, we employ the group theory approach to directly link the governing equations to the momentum model, and to precisely derive the buoyancy and drag parameters [...] Read more.

In this work, we theoretically and numerically investigate Rayleigh–Taylor dynamics with constant acceleration. On the side of theory, we employ the group theory approach to directly link the governing equations to the momentum model, and to precisely derive the buoyancy and drag parameters for the bubble and spike in the linear, nonlinear, and mixing regimes. On the side of simulations, we analyze numerical data on Rayleigh–Taylor mixing by applying independent self-similar processes associated with the growth of the bubble amplitude and with the bubble merger. Based on the obtained results, we reveal the constituents governing Rayleigh–Taylor dynamics in the linear, nonlinear, and mixing regimes. We outline the implications of our considerations for experiments in plasmas, including inertial confinement fusion. Full article

(This article belongs to the Special Issue Plasma Physics Highlights: Non-equilibrium Dynamics, Interfaces and Mixing)

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10 pages, 764 KiB

Open AccessCommunication

Modeling Femtosecond Reduction of Atomic Scattering Factors in X-ray-Excited Silicon with Boltzmann Kinetic Equations

by Beata Ziaja, Michal Stransky, Konrad J. Kapcia and Ichiro Inoue

Atoms 2023, 11(12), 154; https://doi.org/10.3390/atoms11120154 - 7 Dec 2023

Viewed by 1642

Abstract

In this communication, we describe the application of Boltzmann kinetic equations for modeling massive electronic excitation in a silicon nanocrystal film after its irradiation with intense femtosecond hard X-ray pulses. This analysis was inspired by an experiment recently performed at the X-ray free-electron [...] Read more.

In this communication, we describe the application of Boltzmann kinetic equations for modeling massive electronic excitation in a silicon nanocrystal film after its irradiation with intense femtosecond hard X-ray pulses. This analysis was inspired by an experiment recently performed at the X-ray free-electron laser facility SACLA, which measured a significant reduction in atomic scattering factors triggered by an X-ray pulse of the intensity ∼

10^{19}

W/cm

^{2}

, occurring on a timescale comparable with the X-ray pulse duration (6 fs full width at half maximum). We show that a Boltzmann kinetic equation solver can accurately follow the details of the electronic excitation in silicon atoms caused by such a hard X-ray pulse, yielding predictions in very good agreement with the experimental data. Full article

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

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13 pages, 3434 KiB

Open AccessArticle

DFT Investigation on the Complexation of β-Cyclodextrin and Hydroxypropyl-β-Cyclodextrin as Recognition Hosts with Trichloroethylene

by Ahlem Benmerabet, Abdelaziz Bouhadiba, Youghourta Belhocine, Seyfeddine Rahali, Najoua Sbei, Mahamadou Seydou, Ihsene Boucheriha, Imane Omeiri and Ibtissem Meriem Assaba

Atoms 2023, 11(12), 153; https://doi.org/10.3390/atoms11120153 - 7 Dec 2023

Cited by 3 | Viewed by 1944

Abstract

In this investigation, the potential use of native β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) as encapsulating agents for trichloroethylene (TCE) was assessed. Various quantum chemical parameters, including HOMO, LUMO, and HOMO–LUMO gap, were calculated. The docking process was examined by considering different initial configurations. [...] Read more.

In this investigation, the potential use of native β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) as encapsulating agents for trichloroethylene (TCE) was assessed. Various quantum chemical parameters, including HOMO, LUMO, and HOMO–LUMO gap, were calculated. The docking process was examined by considering different initial configurations. The complexation energies were calculated at the molecular level using DFT/BLYP-D4 and PBEh-3c calculations to gain insight into TCE encapsulation within the β-CD and HP-β-CD cavities. We used the independent gradient model (IGM) and extended charge decomposition analysis (ECDA) approaches to examine non-covalent interactions and charge transfer within TCE@β-CD and TCE@HP-β-CD complexes. The calculated thermodynamic data and complexation energies exhibited negative values for both considered complexes, indicating a favorable complexation process. Weak Van der Waals intermolecular interactions were the main driving forces in stabilizing the formed complex. Additionally, Monte Carlo simulations were conducted for a better understanding of the inclusion process. Our results provide evidence for the use of β-CD and HP-β-CD as suitable macrocyclic hosts for complexing trichloroethylene. Full article

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23 pages, 3642 KiB

Open AccessArticle

Photoionization Study of Neutral Chlorine Atom

by Momar Talla Gning and Ibrahima Sakho

Atoms 2023, 11(12), 152; https://doi.org/10.3390/atoms11120152 - 6 Dec 2023

Cited by 1 | Viewed by 1579

Abstract

Photoionization of neutral chlorine atom is investigated in this paper in the framework of the screening constant per unit nuclear charge (SCUNC) method. Resonance energies, quantum defects and effective charges of the 3s²3p⁴ (³P_2,1,0) [...] Read more.

Photoionization of neutral chlorine atom is investigated in this paper in the framework of the screening constant per unit nuclear charge (SCUNC) method. Resonance energies, quantum defects and effective charges of the 3s²3p⁴ (³P_2,1,0)ns and 3s²3p⁴ (³P_1,0)nd Rydberg series originating from both the ²P⁰_3/2 ground state and the ²P⁰_1/2 excited state of chlorine atom are reported. The present study believed to be the first theoretical investigation is compared with the recent experimental measurements (Yang et al., Astrophys. J. 810:132, 2015). Good agreements are obtained between theory and experiments. New SCUNC data are tabulated as useful references for interpreting astrophysical spectra from neutral atomic chlorine. Full article

(This article belongs to the Special Issue Photoionization of Atoms)

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11 pages, 881 KiB

Open AccessArticle

Differential Studies of Argon Particle and Antiparticle Interactions: Present Status and Future Possibilities

by Robert D. DuBois and Károly Tőkési

Atoms 2023, 11(12), 151; https://doi.org/10.3390/atoms11120151 - 1 Dec 2023

Viewed by 1481

Abstract

Although the comparison of fully differential ionization data for particle and antiparticle impact provides the ultimate tests of theoretical models, only very low antiparticle beam intensities are available. Hence, few experiments of this type have been performed. Therefore, available experimentally obtained single and [...] Read more.

Although the comparison of fully differential ionization data for particle and antiparticle impact provides the ultimate tests of theoretical models, only very low antiparticle beam intensities are available. Hence, few experiments of this type have been performed. Therefore, available experimentally obtained single and double differential cross-sections, which are much easier to obtain, are compared in order to demonstrate differences when only the projectile mass or charge (+1 or −1) is changed. Included in the comparison are cross-sections calculated for positron and electron impact using a three-particle classical trajectory Monte Carlo method. The calculated cross-sections provide independent information about the ejected electron and the scattered projectile contributions, plus information about the impact parameters, all as functions of the collision kinematics. From these comparisons, suggestions as to where future investigations are both feasible and useful are provided. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Atomic Collision and Atomic Spectroscopy)

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10 pages, 3617 KiB

Open AccessArticle

Spectral Shift and Split of Harmonic Lines in Propagation Affected High Harmonic Generation in a Long-Interaction Gas Tube

by Jozsef Seres, Enikoe Seres, Carles Serrat, Thanh-Hung Dinh, Noboru Hasegawa, Masahiko Ishino, Masaharu Nishikino and Shinichi Namba

Atoms 2023, 11(12), 150; https://doi.org/10.3390/atoms11120150 - 1 Dec 2023

Cited by 1 | Viewed by 1853

Abstract

While generating high harmonics in long media of helium gas, at certain laser intensities and chirp, the spectral shift and split of the harmonic lines were experimentally observed, sometimes exceeding one harmonic order. Beyond reporting these results, numerical simulations were performed to understand [...] Read more.

While generating high harmonics in long media of helium gas, at certain laser intensities and chirp, the spectral shift and split of the harmonic lines were experimentally observed, sometimes exceeding one harmonic order. Beyond reporting these results, numerical simulations were performed to understand the phenomenon. A 3D propagation model was solved under the strong field approximation. According to the simulations, the distortion of the laser beam profile during propagation and the consequently accused change in the conditions of phase matching are responsible for the observations. The observed phenomena can be an excellent tool to produce tunable narrow band harmonic sources covering a broad range around 13.5 nm for spectroscopy and for seeding X-ray lasers, and to understand non-desired detuning of the seed wavelength. Full article

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16 pages, 700 KiB

Open AccessArticle

A Critical Analysis of Target Ionization and Projectile Electron Loss in Neutral– and Ion–Atom Collisions

by Michele A. Quinto, Nicolás J. Esponda, Maria F. Rojas, Roberto D. Rivarola and Juan M. Monti

Atoms 2023, 11(12), 149; https://doi.org/10.3390/atoms11120149 - 21 Nov 2023

Viewed by 1528

Abstract

Electron removal (target ionization and/or projectile electron loss) in neutral–atom collisions is theoretically studied for the impact of H

^{0}

, He

^{0}

and He

^{+}

beams on noble gases (He, Ne and Ar). These reactions are investigated theoretically within the Continuum Distorted [...] Read more.

Electron removal (target ionization and/or projectile electron loss) in neutral–atom collisions is theoretically studied for the impact of H

^{0}

, He

^{0}

and He

^{+}

beams on noble gases (He, Ne and Ar). These reactions are investigated theoretically within the Continuum Distorted Wave-Eikonal Initial State model. New features have been included in the theoretical model: (i) a scaled projectile charge depending on its velocity and charge, (ii) a dynamic projectile-effective-charge depending on the momentum transfer, and (iii) a dynamic target-effective-charge depending on the kinematics of the emitted electron. The energy and angular spectra of emitted electrons from the target and from the projectile are calculated and compared with the available experimental data. Also, the influence of each one of the corrections on the resulting spectra will be studied. Full article

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

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Atoms, Volume 11, Issue 12 (December 2023) – 10 articles

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