When ionizing radiation elicits unforeseen processes: dynamics beyond the coulomb explosion.

When ionizing radiation interacts with molecules or clusters in the gas phase, it induces their ionization and excitation. This phenomenon is observable regardless the type of ionizing radiation used, including collisions with multiply charged ions, energetic synchrotron radiation, or intense laser fields. The direct consequence of this interaction is the formation of molecular species with high degrees of excitation and ionization, leading to fragmentation into two or more positively charged moieties which repeal each other, the so-called Coulomb explosion. However, alongside this process, a variety of other phenomena occur in competition; these include intramolecular charge transfer [1,2], hydrogen migration [3,4], roaming of a neutral fragment [6,7] or even intermolecular reactivity in a cluster forming larger species [8,9]. These reactions are triggered by ionization and excitation and can only be observed if they occur within the femtosecond timescale characteristic of the Coulomb explosion. In this communication I will present a detailed study of the dynamics of these unexpected processes. Specifically, I will show how, through the integration of state-of-the-art experiments, where ions are detected in coincidence, with simulations based on quantum chemistry, we can infer a comprehensive understanding of such reactions and track their dynamics, thereby unambiguously characterizing competing channels.