Direct excitation in heavy-atom collisions: a propensity rule for charge cloud orientation

摘要: The Massey criterion prescribes maximum electronic excitation of atoms in heavy-particle collisions for collision velocities v, where Δea v π. Here Δe is the energy defect and a effective interaction length. Experiments with planar symmetry have revealed preferred way rotation excited charge cloud this velocity region. We demonstrate by analysis simple, yet realistic model why favours states specific orientation. A general propensity rule derived its validity evaluated case, Na-He system. Implications future experiments are pointed out. In particular, role predicts very different behaviours oppositely oriented atoms, as prepared, e.g., circular polarized laser light.