Laser spectroscopy of doubly‐excited states in barium

With pulsed and cw laser radiation we investigated doubly‐excited, autoionizing states of Ba, 4fnf series were excited from metastable 5d2 states using two pulsed dye lasers and 5dnf intermediate states. To explain the data on high‐lying states knowledge of the wave functions of the intermediate states and their perturbers is prerequisite. In preparation of experiments on double circular states such as 4f2, 4f5g, 5g2 etc., we studied the 5d5g multiplet, excited with two pulsed lasers from 6s5d metastable states. Furthermore we present results of a study of 6pnl states with large l, excited with two narrowband cw lasers. 6snl states were populated in a beam from metastable 5d2 states in the presence of an electric field. The atomic motion was used to reduce the field adiabatically to zero before applying the second excitation step (Stark switching). The results show that further excitation to 7dnl and even Nfnl states is feasible, giving possibilities to study the three‐body Coulomb problem with cw laser r...