Opened 3 years ago

#287 new enhancement

3He hyperfine collision rate update

Reported by: Gary J. Ferland Owned by: nobody
Priority: good to do Milestone:
Component: atomic/molecular data base Version: trunk
Keywords: Cc:

Description

Title:	
Hyperfine-changing Transitions in 3He II and Other One-electron Ions by Electron Scattering
Authors:	
Bartschat, Klaus; Sadeghpour, H. R.
Affiliation:	
AA(Department of Physics and Astronomy, Drake University, Des Moines, IA 50311, USA klaus.bartschat@drake.edu), AB(ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA hrs@cfa.harvard.edu)
Publication:	
The Astrophysical Journal, Volume 788, Issue 1, article id. 69, 4 pp. (2014). (ApJ Homepage)
Publication Date:	
06/2014
Origin:	
IOP
Astronomy Keywords:	
atomic data, atomic processes, dark ages, reionization, first stars, early universe, radio lines: general
DOI:	
10.1088/0004-637X/788/1/69
Bibliographic Code:	
2014ApJ...788...69B
Abstract

We consider the spin-exchange (SE) cross-section in electron scattering from 3He 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+ 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+ 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 × 10–6 cm3 s–1 and 
K(100 K) = 3.49 × 10–7 cm3 s–1.

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