Wave packet dynamics and autoionization of doubly excited states in molecules can be studied by combining an intense, short-pulse infrared (IR) laser and a extreme ultraviolet (XUV) source with a Reaction Microscope, which allows for coincident measurements of ions and electrons. Furthermore, this detection system is capable of measuring the three dimensional momentum of each charged particle involved in the ionization process.
This technique was used to investigate the autoionization of doubly excited H2 molecules, a process that occurs on a timescale of a few femtoseconds. Since this reaction time is of the order of the molecular motion, the nuclei can no longer be regarded as stationary. The coupling of the dissociation dynamics of H2+ to the corresponding electron, which is emitted through the autoionization of doubly excited states, leads to a symmetry breaking in the dissociation. In the conducted measurements, this translates into a localization of coincident electron-ion pairs. In order to study the temporal dynamics of these processes, the molecules were further probed with delayed IR pulses, revealing dynamics within the autoionization.