Relaxation dynamics of the mass-selected hydrated Auride ion (Au−)

By using time-resolved photoelectron spectroscopy, decay of optically excited states of hydrated Au− mass-selected in the gas phase was studied. It is suggested that the pump-photon can induce injection of an electron from auride chromophore to the water solvent. The cluster with three water molecules (Au−(H2O)3) showed a long-living excited state with a lifetime of ∼19 ± 3 ps, whereas that of Au−(H2O)2 is only ∼3 ± 1 ps. The fate of an optically excited state of an ionic species can be significantly changed by the number of water (solvent) molecules attached.