Quantum and classical transport of excited states of ions

We study the dynamics of the internal state of fast ions traversing amorphous foils using an approach that incorporates the interaction with the radiation field and the complex array of collisions with particles in the solid within the framework of system-reservoir interactions. We have developed from first principles a quantum master equation describing the dynamics of the internal states, including both sinks (electron loss) and sources (electron capture). We illustrate signatures of coherences in experimental findings and discuss the applicability of the quantum and classical linear limits.