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The photoelectron spectra of (H2O)(n = 2-69) - and (D2O)(n = 2-23) - are presented, and their spectral line shapes are analyzed in detail. This analysis revealed the presence of three different groupings of species, each of which are seen over the range, n = 11-16. These three groups are designated as dipole boundlike states, seen from n = 2-16, intermediate states, found from n = 6-16, and bulk embryonts, starting at n = 11 and continuing up through the largest sizes studied. Almost two decades ago [J. V. Coe et al., J. Chem. Phys. 92, 3980 (1990)], before the present comprehensive analysis, we concluded that the latter category of species were embryonic hydrated electrons with internalizing excess electrons (thus the term embryonts). Recent experiments with colder expansion (high stagnation chamber pressures) conditions by Neumark and coworkers [J. R. R. Verlet et al., Science 307, 93 (2005)] have also found three groups of isomers including the long-sought-after surface states of large water cluster anions. This work confirms that the species here designated as embryonts are in the process of internalizing the excess electron states as the cluster size increases (for n > or = 11).

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A theoretical prediction on intermolecular monoelectron dihydrogen bond H e H in the cluster anion ( FH ) 2 {e}( HF ) 2We report the negative ion photoelectron spectra of (NH 3 ) nϭ41-1100 Ϫ , recorded using 2.540 eV photons. The largest cluster anion in this series has a diameter of approximately 4.3 nm. The vertical detachment energies ͑VDEs͒ of these cluster anions increase smoothly from 0.55 eV for nϭ41 to 1.05 eV for nϭ1100. The VDEs throughout this size range are linear with n Ϫ1/3 and extrapolate to a VDE (nϭϱ) value, which is very close to the measured photoelectric threshold energy of condensed phase ammoniated electrons. The linear extrapolation of this data to an analogous condensed phase property implies that these cluster anions are gas-phase counterparts to ammoniated electrons, i.e., they are embryonic forms of ammoniated electrons which will mature with increasing cluster size to become condensed phase-solvated electrons. The VDE data further implies that these embryonic ammoniated electrons were generated in solid ammonia environments, consistent with the source conditions under which they were produced.

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