Dissociations of water ions after valence and inner-valence ionization

Energy selected and mass-resolved electron-ion coincidence spectra of heavy water have been recorded for ionization energies from 18 to 35 eV. Dissociation from the B2B2 state produces both O+ and D2+ at energies near their thermodynamic thresholds in addition to the known products D+ and OD+. The relative yields of O+, OD+, and D+ in the B2B2 state breakdown diagram are modulated by the vibrational structure of the B-state population, implying incomplete energy equilibration before fragmentation. Decay from the C-state produces OD+ in addition to the known O+ and D+. The fragment kinetic energies suggest that O+ and D+ from the C state are the products of full atomization of the molecule.