Theoretical atomic collision physics

The current focus of the research is low-energy (collision v<<bound ve) inelastic collisions for selected systems that possess the characteristic that many intermediate states are strongly coupled, such as can occur in classes of excited-atom (including Rydberg atom) collisions with atoms, molecules and positive and negative ions: (1) We are interested in the dependence of various differential and total cross sections on the angular momentum of the initial excited state and on the alignment of the initial electron charge distribution (for non-spherical initially excited states). (2) We wish to understand how characteristics of the classical trajectories (in CTMC calculations), e.g. multiple encounters, quasi-periodicity, chaos, relate to characteristics of the probability (scattering) amplitudes obtained from semiclassical (quantum mechanical) treatments. (3) In particular, in order to investigate a range of ''interaction regimes,'' we have proposed to study low-Rydberg-atom collisions with: ions and polar molecules (long range interaction); non-polar molecules and atoms (short-range interaction); as well as electron-attaching atoms/molecules (transient electron capture possible). (4) We plan to look for observable signatures of possibly novel intracollisional interference effects and quasi-vibrational resonance effects that may occur in low-Rydberg collisions