DYNAMICS OF 3-BODY REACTIONS IN ICN2+ AND RELATED MOLECULES

Correlations between the initial momenta of fragments from atomisation of ICN2+ and related molecules arc examined by the photoelectron-photoion-photoion coincidence technique. The shapes of peaks in the spectra show that some fragmentation reactions are stepwise but faster than rotation of the intermediates; lifetimes in the subpicosecond range are estimated. Deviations of the peak shapes from predictions based on slow stepwise reaction are attributed both to reaction within the Coulomb repulsion zone and to energy release in decay of aligned intermediates. Suppression of rotation in intermediate ions by the strong Coulomb field is important in interpretation of the mechanisms.