Resonant auger decay of above-threshold core-excited H2O

The decay properties of an above-threshold resonance in core-ionized water, which is difficult to. identify with usual spectroscopic methods, have been analyzed by resonant Auger spectroscopy. The resonance is. shown to correspond to a doubly excited neutral state embedded in the O 1s ionization continuum. The main, result of the experiments is the assessment on the dissociative nature of the intermediate state, with a consequent fragmentation in H neutral plus O*H core excited. This dissociation takes place on the same time scale.. as electron decay, and therefore is categorized as an ultrafast. dissociation process.