Energetic Rydberg neutrals from water dissociation

Abstract

Dissociation of isolated water molecules has been addressed using the technique of time-of-flight spectrometry employing multi-hit detection in an ion-molecule collision experiment. Ar9+ ions having energy of 450 keV were used as projectiles for inducing dissociation. We have detected neutral fragments (fast, energetic Rydberg hydrogen atoms) originating from the dissociation process in coincidence with charged fragments. The kinetic energies of the neutral atoms have been determined by time-of-flight measurements. The formation of transient Rydberg molecular ions is also inferred from the experimental data. The implications of the results are discussed in context of the observation of energetic neutral atoms in extra-solar planets and radiation damage in living systems where water plays a major role.