Cross sections and rates for the excitation of complex ions by electron impact

The single configuration scaled collision strength expressions for all transitions in one and two valence electron ions in the limit Z → infinity obtained in an earlier work are reviewed. This method is then extended to give expressions for the single configuration scaled collision strengths for the principal transitions in three valence electron ions in the limit Z → infinity. The expressions for the one, two, and three valence electron ion collision strengths reduce to a very simple form involving hydrogenic ion collision strengths when configuration mixing is neglected. These expressions have been applied to the available hydrogenic ion data to obtain numerical results for collision strengths for transitions involving principal quantum number n less than or equal to 3. The numerical results have been fit to analytic expressions which are readily integrated over a Maxwellian velocity distribution to obtain collision rates. This approach has also been extended to include configuration mixing. Mixing coefficients and mixed collision strengths have been calculated in the limit Z → infinity for important transitions in beryllium-like ions as well as for the inner-shell excitation transitions in boron-like ions