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Title: Ionization in Fast Atom-Atom Collisions: The Influence and Scaling Behavior of Electron-Electron and Electron-Nuclear Interactions

Abstract

We report cross sections for ionization of He coincident with electron loss from He, Li, C, O, and Ne pro jectiles. For He, Li, C, and O pro jectiles, the cross sections were measured directly, while the Ne cross sections were obtained by transforming results for He pro jectiles colliding with Ne. We find that, at energies of about 100-500 keV/u, neutral pro jectiles can ionize a He target almost as effectively as a charged pro jectile. The contribution to ionization due to electron-electron interactions is found to scale with the number of available pro jectile electrons. Comparing ionization by the bound electrons on projectiles to ionization by free electrons, we find the cross sections for ionization by bound electrons are systematically smaller than those for free electrons.

Authors:
 [1];  [2];  [3];  [4];  [4];  [4];  [4];  [4]
  1. University of South Alabama, Mobile
  2. University of Missouri, Rolla
  3. Georgia State University, Atlanta
  4. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
931105
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review A; Journal Volume: 76; Journal Issue: 6
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 74 ATOMIC AND MOLECULAR PHYSICS; ATOM-ATOM COLLISIONS; CROSS SECTIONS; ELECTRON LOSS; ELECTRON-ELECTRON INTERACTIONS; ELECTRONS; IONIZATION; PROJECTILES; TARGETS

Citation Formats

Sanders, Justin M., DuBois, R. D., Manson, S. T., Datz, Sheldon, Deveney, Edward, Krause, Herbert F, Shinpaugh, Jefferson, and Vane, C Randy. Ionization in Fast Atom-Atom Collisions: The Influence and Scaling Behavior of Electron-Electron and Electron-Nuclear Interactions. United States: N. p., 2007. Web. doi:10.1103/PhysRevA.76.062710.
Sanders, Justin M., DuBois, R. D., Manson, S. T., Datz, Sheldon, Deveney, Edward, Krause, Herbert F, Shinpaugh, Jefferson, & Vane, C Randy. Ionization in Fast Atom-Atom Collisions: The Influence and Scaling Behavior of Electron-Electron and Electron-Nuclear Interactions. United States. doi:10.1103/PhysRevA.76.062710.
Sanders, Justin M., DuBois, R. D., Manson, S. T., Datz, Sheldon, Deveney, Edward, Krause, Herbert F, Shinpaugh, Jefferson, and Vane, C Randy. Mon . "Ionization in Fast Atom-Atom Collisions: The Influence and Scaling Behavior of Electron-Electron and Electron-Nuclear Interactions". United States. doi:10.1103/PhysRevA.76.062710.
@article{osti_931105,
title = {Ionization in Fast Atom-Atom Collisions: The Influence and Scaling Behavior of Electron-Electron and Electron-Nuclear Interactions},
author = {Sanders, Justin M. and DuBois, R. D. and Manson, S. T. and Datz, Sheldon and Deveney, Edward and Krause, Herbert F and Shinpaugh, Jefferson and Vane, C Randy},
abstractNote = {We report cross sections for ionization of He coincident with electron loss from He, Li, C, O, and Ne pro jectiles. For He, Li, C, and O pro jectiles, the cross sections were measured directly, while the Ne cross sections were obtained by transforming results for He pro jectiles colliding with Ne. We find that, at energies of about 100-500 keV/u, neutral pro jectiles can ionize a He target almost as effectively as a charged pro jectile. The contribution to ionization due to electron-electron interactions is found to scale with the number of available pro jectile electrons. Comparing ionization by the bound electrons on projectiles to ionization by free electrons, we find the cross sections for ionization by bound electrons are systematically smaller than those for free electrons.},
doi = {10.1103/PhysRevA.76.062710},
journal = {Physical Review A},
number = 6,
volume = 76,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • We report cross sections for ionization of He coincident with electron loss from He, Li, C, O, and Ne projectiles. For He, Li, C, and O projectiles, the cross sections were measured directly, while the Ne cross sections were obtained by transforming results for He projectiles colliding with Ne. We find that, at energies of about 100-500 keV/u, neutral projectiles can ionize a He target almost as effectively as a charged projectile. The contribution to ionization due to electron-electron interactions is found to scale with the number of available projectile electrons. Comparing ionization by the bound electrons on projectiles tomore » ionization by free electrons, we find that the cross sections for ionization by bound electrons are systematically smaller than those for free electrons.« less
  • The influence of inelastic nuclear scattering on atomic charge transfer in asymmetric ion-atom collisions is described within a new theory, combining a two-channel model for the nuclear reaction with the impulse approximation for electron capture by the projectile. Test calculations of the capture probability during the reaction {sup 18}O({ital p},{alpha}){sup 15}N indicate that inelastic nuclear reactions are a more transparent probe for the atomic transition amplitudes than elastic resonances.
  • Absolute doubly differential cross sections for electron emission are presented for 0.5-MeV/u multicharged ion-atom collisions. The collision systems investigated are B[sup [ital q]+], C[sup [ital q]+] ([ital q]=2--5) and O[sup [ital q]+], F[sup [ital q]+] ([ital q]=3--6) projectiles impacting on helium and C[sup [ital q]+] ([ital q]=2--5) ions impacting on neon and argon targets. Laboratory electron emission angles between 10[degree] and 60[degree] were studied. Under the assumption that the cross sections scale with the square of an effective projectile charge, [ital Z][sub [ital e][ital f][ital f]]([var epsilon],[theta]), the scaling was investigated as a function of emitted electron velocity and angle.more » For distant collisions (low-energy electron emission), we find that [ital Z][sub [ital e][ital f][ital f]]([var epsilon],[theta])[gt][ital q] for small [ital q]. For the highest values of [ital q] investigated, [ital Z][sub [ital e][ital f][ital f]]([var epsilon],[theta]) was found to be smaller than the net projectile charge [ital q]. The effective projectile charges may be subject to a systematic underestimation since they were determined by referencing the partially stripped ion impact data to fully stripped boron, rather than proton, impact cross sections. In the binary-encounter region, the present data confirm previously observed features--namely that the emission increases as [ital q] decreases. For the helium target, the qualitative behavior is roughly in accordance with predictions by Schulz and Olson [J. Phys. B 24, 3409 (1991)]. Neon and argon targets also demonstrate these features, but less dramatically than helium.« less