Double-Auger decay, Feshbach and shape resonances in negative ions

Inner-shell photoionization of negative ions is very different from photoionization of neutral or positive ions. The short-range interaction that governs negative ions leads to new and different physics. Negative ions exist because of electron correlation that is so strong that it leads to strong simultaneous double-Auger decay, as well as shape and Feshbach resonances. Our recent work has also shown that inner-shell photoionization obeys the Wigner law even when post-collision interaction affects the cross-section.