Close-coupling studies on target electron excitation in slow atomic collisions

The collision strengths for transitions between levels of Fexiv have been calculated using the close coupling and the Coulomb-Born I methods. It is shown that the Coulomb-Born I approximation gives reliable results for highly ionized ions.The electron excitation rate coefficient for the transition in the 3s2 3p configuration, giving rise to the green coronal line, has been investigated in detail. The quantum defect method, which takes into account the excitation via autoionization levels of FeXIII, has been used. This process greatly increases the excitation rate for low energies of the incident electron.The statistical equilibrium populations of the FeXIV levels have been calculated under coronal conditions, and the effective excitation rate coefficient for the green coronal line is given for a wide range of temperatures and densities.

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Monocentric Close-Coupling Expansion to Provide Ejected Electron Distributions for Ionization In Atomic Collisions

Physical Review Letters ◽

10.1103/physrevlett.84.4569 ◽

2000 ◽

Vol 84 (20) ◽

pp. 4569-4572 ◽

Cited By ~ 47

Author(s):

B. Pons

Keyword(s):

Atomic Collisions ◽

Close Coupling ◽

Electron Distributions

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Ability of monocentric close-coupling expansions to describe ionization in atomic collisions

Physical Review A ◽

10.1103/physreva.63.012704 ◽

2000 ◽

Vol 63 (1) ◽

Cited By ~ 31

Author(s):

B. Pons

Keyword(s):

Atomic Collisions ◽

Close Coupling

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Collision Strengths for Electron Excitation of Coronal Ions

Highlights of Astronomy ◽

10.1017/s1539299600000514 ◽

1971 ◽

Vol 2 ◽

pp. 512-517 ◽

Cited By ~ 2

Author(s):

D. R. Flower

Keyword(s):

Atomic Structure ◽

Electron Excitation ◽

Bound State ◽

General Purpose ◽

Close Coupling ◽

Collision Problem ◽

University College London ◽

General Purpose Computer ◽

Purpose Computer ◽

Structure Programme

Using general purpose computer programmes developed by Drs. Eissner and Nussbaumer at University College London for the solution of atomic structure and atomic collision problems, collision strengths have been obtained for transitions between terms of the ground and first few excited configurations of ions of interest in studies of the solar corona. The atomic structure programme is written in a configuration interaction representation and uses a scaled Thomas-Fermi potential as described by Eissner and Nussbaumer (1969). The bound state wave functions generated by the structure programme are used by the collision programme (Eissner, 1970) to calculate the R-matrix solution of the collision problem by means of the distorted wave approximation (Saraph et al., 1969). This approximation should be valid for highly ionized ions such as exist in the corona and this prediction is fully confirmed where comparison can be made with calculations using the more rigorous but more time-consuming close coupling method (Burke et al., 1966; Petrini, 1969).

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