Study of the Water Molecule in the Gaseous Phase Excited States of H2O,H2O+ and H2O−

A short account of the electron configuration of water, including symmetry properties, is given. These simple considerations permit the explanation of the results of photoelectron spectroscopy experiments and photoionization experiments; the ²B₂ state of H₂O⁺ is predissociated. Excited states of water are all repulsive or predissociated, the more important fragments being OH²τ, OH²Σ⁺ and O. Some repulsive states of H₂O^? are known, but the important low-lying ²A′ state is unknown.