Electronic absorption spectra of size-selected hydrated electron clusters: (H2O)n−, n=6–50

We report photodestruction spectra for the (H2O)n− clusters (n=6, 11, 15, 20, 25, 30, 35, 40, and 50) in the range 0.7–1.6 eV. The spectra are observed to strongly redshift and narrow with decreasing cluster size, with a concomitant increase in peak intensity. The maxima occur well below the vertical detachment energies for n20 and almost exclusively result from excitation of a bound–bound transition.