Abstract

This study focuses on the role of negative-ion formation in the decay of core-valence doubly excited water molecules. Combining negative- and positive-ion coincidence measurements with calculated energies of core-valence doubly excited states, we find that O⁻ and H⁻ production is enhanced selectively. In particular, we suggest that O⁻ production is correlated to double occupancy of the antibonding 4a₁ virtual orbital, while H⁻ appears at electronic states with double occupancy in 2b₂. We also show that H⁻ and O⁻can be created as a result of electron recapture close to the O 1s ionization potential.