Collisional Excitation Rate Coefficients for Lithium-Like Ions

This report takes all the available good quality quantal calculations of excitation cross-sections by electron collision for lithium-like ions and intercompares them. There is a comparison also with the small amount of experimental data of 2 s 2 S -2 p 2 P cross-sections. On the basis of all of these data, a choice is made of the best cross-sections and these are integrated over Maxwellians to give excitation rate coefficients. In general data are available for up to seven transitions in five or six ions. When the results are compared along the iso-electronic sequence, trends are established which allow estimates to be made of the rate coefficients for these seven transitions for any lithium-like ion of nuclear charge greater than boron. The results are presented graphically and as simple formulae. The formulae reproduce the source data at various levels of accuracy from about ± 1% for individual ions to universal formulae of accuracy better than ± 15% in the relevant temperature ranges. The latter are contained on one page and represent an enormous condensation of the original source data without seriously compromising the authors' claimed accuracy.