Ultrafast Hot-Electron Dynamics Observed inPt3−Using Time-Resolved Photoelectron Spectroscopy

Time-resolved two-photon photoelectron spectra have been measured for free ${\mathrm{Pt}}_3^{-}$ using femtosecond pulses of 1.5 eV photon energy in a pump-probe configuration. The time-dependent photoelectron distribution reveals a lifetime of optically excited states of less than 70 fs. Such an unexpected fast electron relaxation in ${\mathrm{Pt}}_3^{-}$ suggests the existence of inelastic electron-electron scattering processes in a triatomic cluster which result in a lifetime similar to those of bulk metals.