Electron impact excitation of Si II and Fe XIV

Energy levels, radiative rates, lifetimes, collision strengths and effective collision strengths are calculated for two important Al-like ions, namely Si II and Fe XIV. For Si II, the lowest 56 levels of the 3s²3p, 3s3p² 3p³ 3s²3d, 3s3p3d, 3s²4ℓ and 3s²5ℓ configurations are included, whereas for Fe XIV additional 80 levels of 3p²3d, 3s3d² and 3p3d² are considered, but not of 3s² 5ℓ. For the determination of atomic structure GRASP has been adopted and radiative rates are calculated for all E1, E2, Ml and M2 transitions. Electron impact excitation collision strengths are calculated with the DARC code, over a wide energy range, and resonances are resolved in a fine energy mesh to determine effective collision strengths over a wide range of temperatures. Extensive comparisons are made for all atomic parameters with available theoretical and experimental data, and the accuracy of the present results is assessed. Energy levels are estimated to be accurate to ∼1% and all other parameters to be better than 20%