Photoelectron Spectroscopy of Mass-Selected Copper-Water Cluster Negative Ions

Negative-ion photoelectron spectroscopy has been applied in order to obtain size dependent information about the electronic structure of clusters of metal atoms solvated with polar molecules. In the present paper we have investigated the photoelectron spectra of Cu₂^-$$, cluster ions with 2 = 0–4 and also those of Cu₂^-$$, with n = 0 and 1. In the spectra of Cu₂^-$$, the lowest energy bands were assigned to the electron detachment from the CuOH^-$$, which were produced in the source together with the above cluster ions. The observed bands for Cu₂^-$$ were all assigned to the transitions to the states originating in the ground ²S and first excited ²D states of the Cu atom. The stepwise hydration for Cu^- and Cu₂^- was discussed from the observed spectral shifts.