Excited-State Relaxation of Ag~8 Clusters Embedded in Helium Droplets

Neutral silver clusters Ag N are grown in ultracold helium nanodroplets. By exploiting a strong absorption resonance recently found for Ag 8 , first photoelectron spectra of this neutral species are recorded. Variation of the laser photon energy reveals that direct vertical two-photon ionization is hindered by rapid relaxation into the lower edge of a long-living excited state manifold. The analysis of the dynamics gives a precise value of (6.89 ′ 0.09) eV for the vertical ionization potential of Ag 8 . The influence of the helium matrix on photoemission is discussed.