Electron impact excitation of Si XIV: collision strengths and rate coefficients

Abstract

Collision strengths for all transitions up to and including the n = 5 levels of Si XIV have been computed in the LS coupling scheme using R-matrix approach. Care has been taken to ensure the convergence of collision strengths and resonances have been resolved in a fine mesh of electron energy in the threshold energy region. These resonances are shown for a few selected transitions, particularly for those among the lower excited levels, but collision strengths are tabulated for all transitions in the energy range 189-215 Ry. Additionally, these are integrated over a Maxwellian distribution of electron velocities to obtain the effective collision strengths from which the excitation and deexcitation rate coefficients can be easily obtained. The results for effective collision strengths are tabulated in the electron temperature range of log Te = 4.0-6.40 K and are compared with the earlier available data.