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Recent Advances in Ion-Impact Atomic Collisions: Experiment, Theory and Applications

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A special issue of Atoms (ISSN 2218-2004).

Deadline for manuscript submissions: closed (31 January 2019) | Viewed by 18569

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Special Issue Editors

Prof. Dr. Tom Kirchner

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Guest Editor

Department of Physics & Astronomy, York University, 4700 Keele Street, Toronto, ON, Canada
Interests: atomic scattering theory; quantum dynamics of few-body Coulomb systems; ion-atom and ion-molecule collisions; density functional theory approach to the many-body problem

Prof. Dr. Michael Schulz

E-Mail Website
Guest Editor

Department of Physics, Missouri University of Science and Technology, Rolla, MO 65409, USA
Interests: atomic collisions; few-body problem; coherence effects; correlation effects
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Ion-impact atomic collision studies have shaped our understanding of the microscopic world and continue to play an important role in shedding light on fundamental properties and processes of atomic and molecular few-body systems. At the same time, they provide insight and data of relevance for more applied research directions such as the study of fusion plasmas, X-ray emissions of astrophysical objects, and radiation damage of biological tissue. For this special issue we invite original contributions covering all aspects of contemporary heavy-particle atomic collision physics, ranging from the development of new theoretical or computational approaches and experimental techniques to the calculation and measurement of cross section data for specific processes and the use of collisional data in plasma modeling and other areas. The goal is to provide a snapshot of current research in the field, of new insights, developments, and applications and of open problems.

Prof. Dr. Tom Kirchner
Prof. Dr. Michael Schulz
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Atoms is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

basic processes in ion-atom, ion-molecule, and ion-cluster collisions
few-body dynamics
fragmentation of molecules and clusters by ion impact
postcollisional de-excitation processes (radiative vs. Auger)
ion-biomolecule interactions
laser-assisted collisions
coherence, electron-electron correlation, and relativistic effects
experimental techniques and instrumentation
applications of ion-impact collisions

Published Papers (6 papers)

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Research

15 pages, 2818 KiB

Open AccessArticle

Frozen Core Approximation and Nuclear Screening Effects in Single Electron Capture Collisions

by Allison Harris

Atoms 2019, 7(2), 44; https://doi.org/10.3390/atoms7020044 - 12 Apr 2019

Cited by 5 | Viewed by 3021

Abstract

Differential cross sections (DCS) for single electron capture from helium by heavy ion impact are calculated using a frozen core 3-body model and an active electron 4-body model within the first Born approximation. DCS are presented for H⁺, He²⁺, Li³⁺, and C⁶⁺ projectiles with velocities of 1 MeV/amu and 10 MeV/amu. In general, the DCS from the two models are found to differ by about one to two orders of magnitude with the active electron 4-body model showing better agreement with experiment. Comparison of the models reveals two possible sources of the magnitude difference: the inactive electron’s change of state and the projectile–target Coulomb interaction used in the different models. Detailed analysis indicates that the uncaptured electron’s change of state can safely be neglected in the frozen core approximation, but that care must be used in modeling the projectile–target interaction. Full article

(This article belongs to the Special Issue Recent Advances in Ion-Impact Atomic Collisions: Experiment, Theory and Applications)

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7 pages, 1038 KiB

Open AccessArticle

Distortion of the Ionization Cross Section of He by the Coherence Properties of a C⁶⁺ Beam

by Francisco Navarrete, Raúl Barrachina and Marcelo F. Ciappina

Atoms 2019, 7(1), 31; https://doi.org/10.3390/atoms7010031 - 01 Mar 2019

Cited by 4 | Viewed by 2421

Abstract

We analyze the influence of the coherence of the projectile’s beam in scattering phenomena. We focus our study in the ionization of He by

C^{6 +}

projectiles at 100 MeV/amu. We assess the influence of this effect by performing a Born initial [...] Read more.

We analyze the influence of the coherence of the projectile’s beam in scattering phenomena. We focus our study in the ionization of He by

C^{6 +}

projectiles at 100 MeV/amu. We assess the influence of this effect by performing a Born initial state and continuum distorted wave final state (CDW-B1) calculation together with a rigorous procedure to account for the initial coherence properties of the projectile’s beam. These calculations, which had been previously performed for only the scattering and perpendicular collision planes and within the First Born approximation (FBA), were repeated for an ampler set of collision planes. Additionally, a more refined method to describe the applicability of the aforementioned procedure, is used. We achieve a better qualitative agreement with the experimental results. Full article

(This article belongs to the Special Issue Recent Advances in Ion-Impact Atomic Collisions: Experiment, Theory and Applications)

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11 pages, 357 KiB

Open AccessArticle

Charge-Exchange Emission from Hydrogen-Like Carbon Ions Colliding with Water Molecules

by Dennis Bodewits and Ronnie Hoekstra

Atoms 2019, 7(1), 17; https://doi.org/10.3390/atoms7010017 - 01 Feb 2019

Cited by 5 | Viewed by 3842

Abstract

Absolute Extreme Ultraviolet emission cross-sections have been measured for collisions between C

^{5 +}

and H

_{2}

O in the range of 0.113 to 3.75 keV/amu (170–979 km/s). These results are used to derive velocity-dependent triplet-to-singlet ratios and emission cross-sections of the C [...] Read more.

Absolute Extreme Ultraviolet emission cross-sections have been measured for collisions between C

^{5 +}

and H

_{2}

O in the range of 0.113 to 3.75 keV/amu (170–979 km/s). These results are used to derive velocity-dependent triplet-to-singlet ratios and emission cross-sections of the Cv K-series following single-electron capture. Comparison with existing measurements of integral charge-changing cross-sections indicates that auto-ionizing multi-electron capture is a significant reactions channel. This reaction may indirectly populate the

n = 2

states and thus add strength to the K

_{α}

emission of Cv ions thereby co-determining the hardness ratio of K-series emission of Cv. Full article

(This article belongs to the Special Issue Recent Advances in Ion-Impact Atomic Collisions: Experiment, Theory and Applications)

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9 pages, 2458 KiB

Open AccessArticle

Transverse Momentum Transfer Distributions Following Single Ionization in 3.6 MeV/amu Au⁵³⁺ + He Collisions: A 4-Body Classical Treatment

by François Frémont

Atoms 2018, 6(4), 68; https://doi.org/10.3390/atoms6040068 - 03 Dec 2018

Cited by 4 | Viewed by 2457

Abstract

A four-body classical model based on the resolution of Hamilton equations of motion was used here to determine and analyze ionization doubly-differential cross sections following 3.6 MeV/amu Au⁵³⁺ + He collisions. Our calculation was not able to reproduce the binary peaks experimentally observed in the transverse momentum distributions for electron emission energies larger than 10 eV. Surprisingly, by introducing a large number of free or quasi-free electrons that followed the projectile at the same velocity, the agreement between the experiment and our calculation was improved, since our model reproduced, at least qualitatively, the experimental binary peaks. The origin of the presence of such electrons is discussed. Full article

(This article belongs to the Special Issue Recent Advances in Ion-Impact Atomic Collisions: Experiment, Theory and Applications)

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18 pages, 817 KiB

Open AccessArticle

Mixed-State Ionic Beams: An Effective Tool for Collision Dynamics Investigations

by Emmanouil P. Benis, Ioannis Madesis, Angelos Laoutaris, Stefanos Nanos and Theo J. M. Zouros

Atoms 2018, 6(4), 66; https://doi.org/10.3390/atoms6040066 - 29 Nov 2018

Cited by 7 | Viewed by 3205

Abstract

The use of mixed-state ionic beams in collision dynamics investigations is examined. Using high resolution Auger projectile spectroscopy involving He-like (

1 s^{2}^{1} S, 1 s 2 s^{3, 1} S

) mixed-state beams, the spectrum contributions of the [...] Read more.

The use of mixed-state ionic beams in collision dynamics investigations is examined. Using high resolution Auger projectile spectroscopy involving He-like (

1 s^{2}^{1} S, 1 s 2 s^{3, 1} S

) mixed-state beams, the spectrum contributions of the

1 s 2 s^{3} S

metastable beam component is effectively separated and clearly identified. This is performed with a technique that exploits two independent spectrum measurements under the same collision conditions, but with ions having quite different metastable fractions, judiciously selected by varying the ion beam charge-stripping conditions. Details of the technique are presented together with characteristic examples. In collisions of 4 MeV B

^{3 +}

with H

_{2}

targets, the Auger electron spectrum of the separated

1 s 2 s^{3} S

boron beam component allows for a detailed analysis of the formation of the

1 s 2 s (^{3} S) n l^{2} L

states by direct

n l

transfer. In addition, the production of hollow

2 s 2 p^{1, 3} P

doubly- and

2 s 2 p^{2}^{2} D

triply-excited states, by direct excitation and transfer-excitation processes, respectively, can also be independently studied. In similar mixed-state beam collisions of 15 MeV C

^{4 +}

with H

_{2}

, He, Ne and Ar targets, the contributions of the

1 s^{2}

1 s 2 s^{3, 1} S

beam components to the formation of the

2 s 2 p^{3, 1} P

states by double-excitation,

1 s \to 2 p

excitation and transfer-loss processes can be clearly identified, facilitating comparisons with theoretical calculations. Full article

(This article belongs to the Special Issue Recent Advances in Ion-Impact Atomic Collisions: Experiment, Theory and Applications)

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16 pages, 5728 KiB

Open AccessArticle

Coherence-Length Effects in Fast Atom Diffraction at Grazing Incidence

by María Silvia Gravielle, Jorge Esteban Miraglia and Leandro Frisco

Atoms 2018, 6(4), 64; https://doi.org/10.3390/atoms6040064 - 27 Nov 2018

Cited by 5 | Viewed by 3009

Abstract

Coherence properties of projectiles, found relevant in ion-atom collisions, are investigated by analyzing the influence of the degree of coherence of the atomic beam on interference patterns produced by grazing-incidence fast-atom diffraction (GIFAD or FAD). The transverse coherence length of the projectiles, which depends on the incidence conditions and the collimating setup, determines the overall characteristics of GIFAD distributions. We show that for atoms scattered from a LiF(001) surface after a given collimation, we can modify the interference signatures of the angular spectra by varying the total impact energy, while keeping the normal energy as a constant. Also, the role played by the geometry of the collimating aperture is analyzed, comparing results for square and circular openings. Furthermore, we study the spot-beam effect, which is due to different focus points of the impinging particles. We show that when a region narrower than a single crystallographic channel is coherently illuminated by the atomic beam, the spot-beam contribution strongly affects the visibility of the interference structures, contributing to the gradual quantum-classical transition of the projectile distributions. Full article

(This article belongs to the Special Issue Recent Advances in Ion-Impact Atomic Collisions: Experiment, Theory and Applications)

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