Electron impact excitation of Al XIII: Collision strengths and rate coefficients

Collision strengths for all transitions up to and including the n = 5 level s of Al XIII have been computed in the LS coupling scheme using the R-matri x code. All partial waves with angular momentum L less than or equal to 45 have been included, and resonances have been resolved in a fine energy grid in the threshold region. Collision strengths are tabulated at energies abo ve thresholds in the range 162.30 less than or equal to E less than or equa l to 220.0 Ry, and results for the 1s-2s and 1s-2p transitions are compared with those of previous authors. Additionally, effective collision strength s, obtained after integrating the collision strengths over a Maxwellian dis tribution of electron velocities, are tabulated over a wide temperature ran ge of 4.40 less than or equal to log T-e less than or equal to 6.40 K.