Resonance Raman studies of the low-lying dissociative Rydberg-valence states of H2O, D2O, and HDO

A resonance Raman study of water has been performed by the use of excitation wavelengths ranging from 200 nm (6.20 eV) to 141 nm (8.78 eV). With excitation resonant with the dissociative A state the spectra exhibit intensity exclusively in the symmetric stretching vibration, showing up to six quanta. There is no activity in the bending or antisymmetric stretching vibrations showing that the dissociation of the A state of water proceeds initially along the symmetry stretch. Resonance with the second absorption band results in a spectrum exhibiting significant intensity in the bending vibration