Direct and indirect ionization processes near the Li `hollow-atom' threshold

Using a unified theoretical treatment of different ionization processes occurring in photon and electron impact on atoms and ions, we examine lithium near its `hollow-atom' threshold. By introducing a set of `core base states' for the target, and optimizing the collisional representation within an R -matrix model, we combine ab initio , outer- and inner-shell effects, excitation and ionization channels, direct and indirect ionization processes, resonant and non-resonant behaviour, for photon and electron impact processes. We use the method to interpret experimental data on electron impact ionization of ground state and photoionization of Li, and look at double photoionization of Li and electron impact ionization out of metastable . We examine and quantify hollow-atom interference effects and resonances, tabulating all 480 states for , and show the chaotic behaviour of overlapping series.