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Title: Hyperfine-changing transitions in {sup 3}He II and other one-electron ions by electron scattering

We consider the spin-exchange (SE) cross-section in electron scattering from {sup 3}He II, which drives the hyperfine-changing 3.46 cm (8.665 GHz) line transition. Both the analytical quantum defect method—applicable at very low energies—and accurate R-matrix techniques for electron-He{sup +} scattering are employed to obtain SE cross-sections. The quantum defect theory is also applied to electron collisions with other one-electron ions in order to demonstrate the utility of the method and derive scaling relations. At very low energies, the hyperfine-changing cross-sections due to e-He{sup +} scattering are much larger in magnitude than for electron collisions with neutral hydrogen, hinting at large rate constants for equilibration. Specifically, we obtain rate coefficients of K(10 K) = 1.10 × 10{sup –6} cm{sup 3} s{sup –1} and K(100 K) = 3.49 × 10{sup –7} cm{sup 3} s{sup –1}.
Authors:
 [1] ;  [2]
  1. Department of Physics and Astronomy, Drake University, Des Moines, IA 50311 (United States)
  2. ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22356657
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 788; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CROSS SECTIONS; ELECTRIC UTILITIES; ELECTRON COLLISIONS; ELECTRONS; GAS UTILITIES; HELIUM 3; HELIUM IONS; HYDROGEN; QUANTUM MECHANICS; R MATRIX; REACTION KINETICS; SCALING; SCATTERING; SPIN EXCHANGE; STARS; UNIVERSE