ELECTRON-IMPACT EXCITATION RATES FOR TRANSITIONS IN BERYLLIUM-LIKE IONS BETWEEN SC-XVIII AND ZN-XXVII

Electron impact excitation rates for the Be-like ion Si XI, Ca XVII an d Fe XXIII, calculated with the R-matrix code, are used to interpolate or extrapolate data (or the ions between Sc XVIII and Zn XXVII. Resul ts for all 45 transitions among the 2s2 1S; 2s2p 3P, 1P; 2p2 3P, 1D an d 1S levels are presented in the form of polynomial fits in log T(e) t o the effective collision strengths (gamma) for each transition. These fits lead to results accurate to an estimated +/- 10%, and are applic able over a temperature range of log T(max) +/- 0.8 dex, where T(max) is the temperature of maximum fractional abundance in ionization equil ibrium of the relevant species. Significant differences between the pr esent results and the earlier distorted-wave calculations of Bhatia et al. for Ti XIX and Ni XXV are found for some transitions.