Fig data of Three-body fragmentation dynamics of C 5H 5N 3+ produced by 200 eVelectron-impact triple-ionization .xlsx

We investigated the electron-impact triple ionization and subsequent fragmentation dynamics of pyridine using multiparticle coincident momentum spectroscopy. Through the measurements of the kinetic energy release-the angle between the conjugate momenta of the first and second breakup steps and Newton diagrams for the three-body Coulomb explosion processes, we separate two distinct sequential mechanisms involving proton emission in the first or second step of sequential fragmentation. Moreover, we determine the relative ratio of the two dissociation pathways for each channel. We find that proton emission in the first step of the sequential dissociation is the dominant process (94% branching ratio) for the channel involving H migration of H+ + CH2N+ + C4H2+. It can be explained by the pyridine trication undergoing ultrafast hydrogen migration and forming a more stable α-isomeric ion, which attenuates the ring-opening reactions.