Three-body dissociation of OCS: Separating sequential and concerted pathways.

Events from the sequential and concerted modes of the fragmentation of OCS that result in coincident detection of fragments C, O, and S have been separated using a newly proposed representation. An ion beam of 1.8 MeV Xe is used to make the triply charged molecular ion, with the fragments being detected by a recoil ion momentum spectrometer. By separating events belonging exclusively to the sequential mode of breakup, the electronic states of the intermediate molecular ion (CO or CS) involved are determined, and from the kinetic energy release spectra, it is shown that the low lying excited states of the parent OCS are responsible for this mechanism. An estimate of branching ratios of events coming from sequential versus concerted mode is presented.