Negative ion photoelectron spectroscopy of solvated electron cluster anions, (H₂O)_n^- and (NH₃)_n^-

The photodetachment spectra of (H₂O)_n^=2-69/- and (NH₃)_n^=41-1100/- have been recorded, and vertical detachment energies (VDEs) were obtained from the spectra. For both systems, the cluster anion VDEs increase smoothly with increasing sizes and most species plot linearly with n^-1/3, extrapolating to a VDE (n=∞) value which is very close to the photoelectric threshold energy for the corresponding condensed phase solvated electron system. The linear extrapolation of this data to the analogous condensed phase property suggests that these cluster anions are gas phase counterparts to solvated electrons, i.e. they are embryonic forms of hydrated and ammoniated electrons which mature with increasing cluster size toward condensed phase solvated electrons.