Time-domain investigation of electron recapture via post-collision interaction in a double photoionization continuum

Picosecond laser pulses have been used to sequentially photoionize both valence electrons from neutral Ba atoms, producing two radially localized continuum wave packets. The Coulomb interaction between the two outgoing electrons can result in the recapture of one of the electrons by the parent ion. The energy distribution of Rydberg ions formed via this "post-collision" interaction is measured as a function of the delay between the ionizing laser pulses. The experimental data are in agreement with the results of both a quantum sudden approximation and a classical simulation.