Distorted-wave methods in the theory of electron-impact exitation of atoms and atomic ions
are reviewed. Principal methods of derivation of the distorted wave approximation are …

Cross sections or effective collision strengths are compiled for electron-impact excitation of
helium atoms and He-like ions. An evaluation is made to identify the “best” determined …

Collisional excitation rate coefficients are given for all 21 fine-structure transitions involving
the ground level and/or singly excited n= 2 levels in 18 He-like ions with nuclear charge …

We measure the energy-differential cross sections for collisional excitation of the soft x-ray
electric-dipole K α (x+ y+ w) emission from He-like oxygen (O vii), using an electron beam …

Recently calculated collision strengths, including relativistic and resonance effects, are
employed to compute Maxwellian averaged collision strengths for all 78 transitions involving …

Electron excitation rates for the ground state to n= 2 and 3 S and P levels in He-like ions
between F VIII and Mn XXIV have been determined by interpolating recent R-matrix and …

The authors present collision strengths calculated using the R-matrix method for transitions
between the five lowest LS states for sodium isoelectronic sequence ions, Al III, Si IV and S …

The Dirac R-matrix theory is used to calculate the collision strengths for electron impact
excitation of He-like ions (S 14+, Ca 18+ and Fe 24+) using the Dirac atomic R-matrix code …

Non-LTE line-formation calculations have been undertaken for Si II, Si III and Si IV ions
using a new grid of model atmospheres. The principal difference to previous calculations is …

The authors have calculated the collision strengths for the electron impact excitation of the
ground state of O VII to the n= 2 and n= 3 states using the R-matrix method. Effective …