We report the experimental observation of free negatively charged water clusters, i.e., ${{\left({\mathrm{H}}_2\mathrm{O}\right)}_n}^{-}$ with $n>~8$. These species have been postulated to occur in irradiated liquids or high-density vapors—the so-called hydrated electrons—but have never been observed so far in the gas phase.

• Received 15 April 1981

DOI:https://doi.org/10.1103/PhysRevLett.47.323