Fragmentation dynamics of the methanol dication

Formation of di- and tri-atomic hydrogen molecular ions during the fragmentation of methanol dication is investigated by coincidence momentum imaging. Site-specific probability for such associative break-ups is determined. Two-body and three-body break-up channels involving association and migration of H atoms are identified. Three-body associative break-ups are found to occur sequentially, triggered by the loss of one H atom, followed by separation of charges. Based on the fragment momentum distributions we propose that H atom migration is induced in the first stage of a three-body sequential break-up, and suggest a structure for the intermediate dication.