Probing and controlling non-Born-Oppenheimer dynamics in highly excited molecular ions

In the extreme ultraviolet and soft-X-ray regions of the spectrum, light-matter interaction is dominated by photoionization. In molecular systems, the sudden removal of an electron will initiate ultrafast electronic and nuclear dynamics in the residual molecular ion. A particularly interesting aspect of these dynamics is the correlated motions of electrons and nuclei, an understanding of which lies at the heart of chemistry. Here we use a few-femtosecond high-harmonic pulse and a weak infrared laser pulse to initiate and probe the explosion of a triatomic N2O+ molecular ion in real time, in a regime dominated by coupled electron-electron and electron-nuclear dynamics. We also show that the branching ratio of bond breaking can be altered in the presence of the laser field.