INTEGRAL AND DIFFERENTIAL CROSS-SECTIONS FOR ELECTRON-IMPACT EXCITATION OF SODIUM-LIKE IONS

Excitations of Na-like ions (Al2+, Si3+, S5+ and Ca9+) by electron imp act are studied theoretically using the R-matrix method Integral and d ifferential cross sections are obtained for the transitions from the g round state (3s) to the 3p, 3d, 4s, 4p and 4d excited states, allowing for coupling between the lowest eleven states. The asymmetry paramete r A, which describes the forward-backward asymmetry of the differentia l cross section is calculated also. The resulting A indicates that the backward scattering dominates in the transition 3s-->3p at low incide nt energy, increasingly with the ionic charge.