Angular distributions for electron-impact excitation of Mg ii, Zn ii, and Cu i

Differential cross sections for excitation of Mg i i, Zn i i, and Cu i from their ground states to the first excited p and d states are calculated for the electron-impact energy range up to 100 eV. In addition, elastic angular distributions for Cu are given at 10 and 100 eV. A five-state close-coupling approximation in which 3s, 3p, 4s, 3d, and 4p states are included is used in the Mg i i calculation. The 4s, 4p, 3$d^9$4$s^2$, 5s, and 4d states are included in the close-coupling calculation for Zn i i, and the 4s, 3$d^9$4$s^2$, 4p, and 4d states for Cu i. For all targets, s→p transitions exhibit strong forward scattering. The same is true for the ions for s→d transitions, but for Cu the 6-eV results are nearly isotropic, and a maximum at 6° is found for higher energies.