The photoionization and photoelectron spectroscopy of He nanodroplets (104 atoms) has been studied by photoelectron imaging with photon energies from 22.5–24.5 eV. Total electron yield measurements reveal broad features, whose onset is ~1.5 eV below the ionization potential of atomic He. The photoelectron spectra are dominated by very low energy electrons, with Ek less than 0.6 meV. These results are attributed to the formation and autoionization of highly vibrationally excited Hen* Rydberg states within the cluster, followed by strong final state interactions between the photoelectron and the droplet.
