PHOTOELECTRON-SPECTROSCOPY OF MASS-SELECTED METAL-WATER CLUSTER NEGATIVE-IONS - CU-(H2O)(N) AND NA-(H2O)(N)

The electronic structures of hydrated metal-atom clusters have been in vestigated by negative-ion photoelectron spectroscopy. We have obtaine d the photoelectron spectra of Cu-(H2O)(n) with n=0-4 and Na-(H2O)(n) with n=0-12. For the former clusters, we also detected the electron de tachment from the CuOH-(H2O)(n-1) which coexists with Cu-(H2O)(n). The observed bands for both Cu-(H2O)(n) and Na-(H2O)(n) were all assigned to the transitions to the states originating in those of the metal at oms, which are shifted as a result of hydration. This result implies t hat the ground states of the neutral clusters still have a one-center character at the size range examined. In contrast, for the Na-water cl usters, increasing character of the Rydberg-type ion-pair state in the negative-ion state is suggested from the vertical-detachment-energy d ependence on the solvent number.