Photoelectron spectroscopy of iodine anion solvated in water clusters

We have measured the photoelectron spectra of clusters of I- solvated in water up to fifteen water molecules. The vertical binding energy of the electron increases with cluster size and levels off in clusters containing more than six water molecules. These results strongly indicate that the first solvation layer around the ion consists of six water molecules. This picture is quantitatively consistent with the photoelectron spectroscopy result of I- solvated in bulk water.