The weakest bond: Collisions of helium dimers with xenon atoms

The existence of an He-2 bound start is employed in an analysis of the possible outcomes from the low-energy collisions between helium dimers and xenon atoms that are currently being observed in molecular beam experiments. Existing interaction potentials between helium atoms and between He and Xe atoms ape used to construct the necessary potential energy surface (PE). Various dynamical approximations for the evaluation of elastic and total cross sections are reviewed, and the results are analyzed in detail, helping us to clarify the specific physical meanings of the various decoupling schemes used in the calculations. The special nature of this unusual diatomic target turns out to play, as expected, a crucial role in the cross section behavior at low collision energies.