Stephen J. Goett

Electron-impact collision strengths for excitation of He-like ions from the levels with n=1 and 2 to all singly excited levels with higher n≤5

Intermediate-coupling collision strengths have been calculated for all transitions of the kind 1s2p2s+1PJ-1sn′l′2s′+1L′J′ with n′=3, 4, and 5 and l′≥1 (p, d, f, g) for 20 He-like ions with nuclear charge number Z in the range 4≤Z≤74. The method used is a Coulomb-Born-Exchange method that is especially well suited for calculating results for many members of an isoelectronic sequence simultaneously. The calculations were made for nine impact-electron energies in threshold units e=1.0, 1.2, 1.5, 1.9, 2.5, 4.0, 6.0, 10.0, and 15.0. The results are given in the form of fits to a simple function of e that is readily integrated over a Maxwellian to obtain collision rates. The parameters required in obtaining collision strengths for the simpler transitions from the 1s2p levels to the 1sn′s levels with 3≤n′≤5 and for the transitions from the ground level and the 1s2s levels to all singly excited levels with higher n values ≤5 are given, as well. Results for transitions between energy terms and their jj coupling analogs are also included. In addition, calculated values for the transition energies and the electric-dipole radiative line strengths are given for all transitions.

Collision strengths and line strengths for fine-structure transitions between the 2la2lb configurations and the 2l′a3l′b configurations in Be-like ions☆

Abstract Collision strengths have been calculated for all fine-structure transitions between the levels of the 2la2lb configurations and those of the 2l′a3l′b configurations in 17 Be-like ions with nuclear charge number Z in the range 10 ⩽ Z ⩽ 74 for nine impact-electron energies ϵ in threshold units in the range 1 ⩽ ϵ ⩽ 15. Fits of all the collision strengths to simple functions of ϵ that are readily integrated over a Maxwellian distribution to obtain collision rates are given. Also given are the results for transitions between energy terms. In addition, the electric-dipole radiative line strengths and the transition energies are listed. The method used is a Coulomb-Born-exchange method that is well suited for handling many members of an isoelectronic sequence simultaneously. The calculations include both configuration mixing and intermediate coupling effects.

Electron-impact collision strengths for inner-shell excitation of doubly excited levels from singly excited levels in He-like ions

Abstract A simple Coulomb-Born-Exchange method has been used to calculate electron-impact colision strengths for inner-shell excitation of the doubly excited levels with n = 2 in He-like ions from the singly excited levels. The results are of particular interest for plasma diagnostic purposes. The calculations were made for nine impact electron energies in threshold units ϵ = 1.0, 1.2, 1.5, 1.9, 2.5, 4.0, 6.0, 10.0 and 15.0 for 19 He-like ions with nuclear charge number Z in the range 6 ≤ Z ≤ 74. Fits are given of the scaled collision strength Z 2 Ω to simple functions of ϵ that are readily integrated over a Maxwellian distribution to obtain collision rates. Configuration-interaction and intermediate-coupling effects have been included in the calculations. Calculated values for transition energies and radiative line strengths are also given.

Collision strengths for innershell excitation of Li-like ions from the 1s22s and 1s22p levels to the 1s2l3l′ levels

Abstract Collision strengths, collision rates, transition energies, and electric-dipole radiative line strengths have been calculated for innershell excitation from the 1s22s and 1s22p levels to all levels of the 1s2l3l′ configurations in Li-like ions with nuclear charge number Z in the range 6 ⩽ Z ⩽ 74. The collision strengths, which are obtained using a Coulomb-Born-exchange method, are expressed in a convenient form in terms of the scaled hydrogenic ion collision strengths Z 2 Ω H and Z 2 Ω H e . Results for innershell excitation to the levels of the 1s2l2l′ configurations considered in earlier work are also expressed in this form. The calculations include configuration mixing, parentage mixing, and intermediate coupling effects.

Collision strengths and line strengths for all transitions among the levels of the 1s22s22p, 1s22s2p2, and 1s22p3 configurations of boron-like ions

Abstract Collision strengths and electric-dipole line strengths have been calculated for all fine-structure transitions among the levels of the 1 s 2 2 s 2 2 p , 1 s 2 2 s 2 p 2 , and 1 s 2 2 p 3 configurations in 17 boron-like ions with nuclear charge number Z in the range 10 ⩽ Z ⩽ 74. From these results the collision strengths and line strengths for transitions between energy terms and their analogs in jj coupling can also be obtained. The collision strength data cover impact-electron energies ⩽ 3.25 Z 2 Ry or 44.2 Z 2 eV. The effects of configuration mixing, parentage mixing, and intermediate coupling have been included in the calculations. The method used in calculating the collision strengths is a Coulomb-Born-Exchange method well suited for treating many members of an isoelectronic sequence simultaneously. The complete results have been given in terms of fits to simple functions of the impact-electron energy that are readily integrated over a Maxwellian distribution to obtain collision rates. Some discussion is given of important differences between the present method and the more usual Coulomb-Born-Exchange method, where it is assumed that the free electron sees the screened nuclear charge ( Z - N ).

collision strengths for innershell excitation of Li-like ions from the 1s23l levels to the 1s2l′3l″ levels☆

Abstract Results are given for collision strengths, collision rates, transition energies, and electric-dipole line strengths for innershell excitation from the 1 s 2 3 l levels to all levels of the 1 s 2 l ′3 l ″ configurations in Li-like ions with nuclear charge number Z in the range 6 ⩽ Z ⩽ 74. The results include the effects of configuration mixing, parentage mixing, and intermediate coupling. A Coulomb-Bornexchange method is used in calculating the collision strengths. The results for collision strengths and line strengths are expressed conveniently in terms of the Z -scaled hydrogenic ion collision strengths and line strength, respectively, together with coefficients that are functions of the target ion mixing coefficients.