Photodissociation dynamics of halogenated aromatic molecules: the case of core-ionized tetrabromothiophene.

We studied the gas-phase photodissociation of a fully halogenated aromatic molecule, tetrabromothiophene, upon core-shell ionization by using synchrotron radiation and energy-resolved multiparticle coincidence spectroscopy. Photodynamics was initiated by the selective soft X-ray ionization of three elements - C, S, and Br - leading to the formation of dicationic states by Auger decay. From a detailed study of photodissociation upon Br 3d ionization, we formulate a general fragmentation scheme, where dissociation into neutral fragments and a pair of cations prevails, but dicationic species are also produced. We conclude that dicationic tetrabromothiophene typically undergoes deferred charge separation (with one of the ions being often Br