DOUBLY EXCITED-STATES

Multistep laser excitation makes it possible to excite one electron at at time in the excitation of doubly excited states. This suppresses the direct continuum excitation, removing the familiar Beutler-Fano interference profiles from the excitation of autoionizing states. Removing this complexity in the excitation process allows one to investigate inherently complex atomic systems, such as interacting autoionizing series. The ability to examine such systems experimentally has led to the development of theoretical techniques based on quantum-defect theory to interpret the experimental results. This powerful combination of complementary experimental and theoretical techniques has led to substantial advances in the study of autoionizing states. © 1987, Optical Society of America.