Femtosecond Ionization of Water Clusters

The figure shows a (H2O)nH+ distribution obtained by femtosecond multiphotonionization of water clusters. The "magic" number at n=21 is clearly observed. Apart from an exponential decay of the parent clusters, unimolecular dissociation products, (H2O)n-1 H+ + H2O, are observed. The fragment intensity is increasing with cluster size.