Photoionization can initiate structural reorganization of molecular matter and drive formation of new chemical bonds. Here, we used time-resolved extreme ultraviolet (EUV) pump - EUV probe Coulomb explosion imaging of carbon dioxide dimer ion dynamics, that combined with ab initio molecular dynamics simulations, revealed unexpected asymmetric structural rearrangement. We show that ionization by the pump pulse induces rearrangement from the slipped-parallel (C2h) geometry of the neutral dimer towards a T-shaped (C2v) structure on the ~100 fs timescale, although the most stable slipped-parallel (C2h) structure of the ionic dimer. Moreover, we find that excited states of the ionized dimer can exhibit formation of a moiety in the complex that can persist even after a suitably time-delayed second photoionization in a metastable dication. Our results suggest that charge asymmetry plays an important role in the ionization-induced dynamics in such dimers that are present in rich environments.
© 2024. The Author(s).