Theory of alignment of atoms following ion-atom collisions

The theory of inner-shell vacancy alignment in ion-atom collisions is reviewed and comparisons to the experimental data are made. Alignment in total as well as differential inelastic scattering cross sections are considered, and the importance of Coulomb deflection and higher multipolarities is stressed. Whereas first-order theories generally work well for projectiles with low charge number, higher-order (coupled-channel-) effects are important for the less asymmetric systems. Despite much recent work in this field many problems remain open, both on the theoretical and the experimental side.