Production of High-Angular-Momentum Rydberg States by Stochastic Collisions

Projectile-centered Rydberg states of highly charged, fast ions traversing thin solid targets show an unexpected abundance of high-$l$ states. We present a theory for the production of high-$l$ states based on classical stochastic dynamics. Diffusion into high-$l$ states is shown to be universal for single-particle orbits in three dimensions under the influence of a stochastic perturbation, i.e., largely independent of the details of the interaction potentials. Monte Carlo simulations using a Langevin equation for stochastically perturbed electrons in a dynamically screened Coulomb field yield quantitative agreement with experimental data.