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Electron capture in collisions of H{sup +} ions with S atoms and its reverse process below kilo-electron-volt energies

Journal Article · · Physical Review A
 [1]; ; ;  [2]; ;  [3];  [4]
  1. School of Allied Health Sciences, Yamaguchi University, Ube, Yamaguchi 755 (Japan)
  2. Theoretische Chemie, Bergische Universitaet-Gesamthochschule Wuppertal, D-42097 Wuppertal (Germany)
  3. Department of Physics, International Christian University, Tokyo (Japan)
  4. Department of Information Science, Ochanomizu University, Tokyo (Japan)
Electron capture in H{sup +}+S({sup 3}P,{sup 1}D) collisions is studied theoretically by using a semiclassical molecular representation with five molecular channels from the initial ground and excited states at collision energies above 10 eV. Electron capture in S{sup +} ({sup 4}S)+H(1s) collisions is also investigated by using three molecular channels in order to assess the earlier estimation which gave the rate constant of 10{sup {minus}15}cm{sup 3}/s at 10{sup 4}K for the process. The {ital ab initio} potential curves and nonadiabatic coupling matrix elements for the HS{sup +} system are obtained from multireference single- and double-excitation configuration-interaction calculations employing relatively large basis sets. Dominant capture channels corresponding to the [H+S{sup +}({sup 2}P)] and [H+S{sup +}({sup 2}D)] states lie lower by 0.2 and 1.4 eV, and 1.34 and 2.5 eV from the initial ground [H{sup +}+S({sup 3}P)] and excited [H{sup +}+S({sup 1}D)] states, respectively. The present results show that electron capture from the excited species is found to be rather weak at lower energies. But it rapidly becomes comparable to that from the ground state. Electron capture in S{sup +} ({sup 4}S)+H collisions proceeds through the two-step mechanism at lower energies, and therefore, the cross section is found to be small with the value less than 10{sup {minus}17}cm{sup 2} below 1 keV, thus supporting the earlier estimation. {copyright} {ital 1997} {ital The American Physical Society}
OSTI ID:
538498
Journal Information:
Physical Review A, Journal Name: Physical Review A Journal Issue: 3 Vol. 56; ISSN 1050-2947; ISSN PLRAAN
Country of Publication:
United States
Language:
English