The dynamics of three-body dissociations of dications studied by the triple coincidence technique PEPIPICO

The triple coincidence PEPIPICO (photoelectron-photoion-photoion coincidence) experiment is shown to be a potent technique to study the dynamics of fragmentations of a dication into two charged and one neutral particle. Initial momenta and relative angles of all three fragments are usually determined, and clear indications are obtained on whether the breakdown is instantaneous or involves sequential steps. For some sequential processes the distance at which secondary breakup occurs can be deduced, while for others the different energy releases in the two steps are determined separately. The technique is here applied to the dissociations into three bodies of the doubly-charged ions of OCS, CS2, NO2, SO2, CH3I and SF6.