Study of the ionic fragmentation of shallow- and core-excited fluorocarbonylsulfenyl chloride, FC(O)SCl:: Observation of a new three-body dissociation mechanism

Total ion yield (TIY) and partial ion yield (PIY) spectra of fluorocarbonylsulfenyl chloride, FC(O)SCI, are reported by using tunable synchrotron radiation. These are the first data obtained for this type of (-C(O)S)-containing compound. Multicoincidence techniques, which include photoelectron-photoion coincidence (PEPICO) and photoelectron-photoion-photoion-coincidence (PEPIPICO) time-of-flight mass spectrometry, are applied to the study of the fragmentation dynamics around the S 2p, Cl 2p, C 1s, O 1s, and F 1s ionization edges. Fragmentation patterns deduced from PEPICO spectra at the various excitation energies are essentially identical. The penta-atomic FC(O)SCI molecule with five different atoms is especially suitable for the analysis of decay mechanisms. Dissociation dynamic processes obtained from PEPIPICO spectra demonstrate the importance of both two- and three-body decay mechanisms, namely, deferred charge separation (DCS) and secondary decay (SD). Furthermore, to explain the behavior of two pairs of ions (F+/Cl+ and S+/CO+) appearing in coincidence, a decay mechanism consisting of a molecular ion rearrangement followed by a secondary decay (SD-IR) is proposed. To our knowledge, such a mechanism has not been reported.