Theory of the l -state population of Rydberg states formed in ion-solid collisions

The experimentally observed high-{ital l}-state population of ions excited in ion-solid interactions differs sharply from {ital l}-state populations produced in ion-atom collisions. We have studied the population dynamics of electronic excitation and transport within the framework of a classical transport theory for O{sup 2+} (2-MeV/u) ions traversing C foils. The resulting delayed-photon-emission intensities are found to be in very good agreement with experiment. Initial phase-space conditions have been obtained from both classical-trajectory Monte Carlo calculations and random initial distributions. We find evidence that the very-high-{ital l}-state populations produced in ion-solid collisions are the result of a diffusion to high-{ital l} states under the influence of multiple scattering in the bulk of the solid.