Production and Photodetachment of Cluster Ions.

Two programs of research are described. In one of these, negative ion photoelectron spectroscopy is applied to study the fundamental properties of the gas-phase cluster anions NO^-(N_2O) _{1,2}, Na_sp {2-5}{-}, K_sp {2-7}{-}, Rb_sp {2,3}{-}, and Cs_sp {2,3}{-}. The photoelectron spectra of No^-(N_2 O)_{1,2} indicate that the excess negative charge is localized on the nitric oxide subunit, which is solvated and stabilized by nitrous oxide. Electron affinities and ion-solvent dissociation energies as a function of cluster size were determined. The photoelectron spectra of the alkali metal negative cluster ions map out electron affinities, anion vertical detachment energies, and electronic state splittings of the neutral clusters with cluster size. Dimeranion dissociation energies have also been determined. The second program of research involves cluster ion formation studies. The design and performance aspects of a variety of cluster ion sources are detailed including: (1) a high temperature supersonic expansion ion source, (2) a directed ion beam sputter source, and (3) a 2000 ^circC capable inert gas nucleation ion source. In addition, the design and construction of an apparatus used to test and characterize these sources is discussed.