Photoelectron spectroscopy of nickel group dimers: Ni:, PdF, and Ptc

Negative ion photoelectron spectra of Ni, , Pd,, and Pt, are presented for electron binding energies up to 3.35 eV at an instrumental resolution of 8-10 meV. The metal cluster anions are prepared in a flowing afterglow ion source. Each dimer exhibits multiple low-lying electronic states and a vibrationally resolved ground state transition. Franck-Condon analyses yield the anion and neutral vibrational frequencies and the bond length changes between anion and neutral. The electron affinities are determined to be EA(Ni,) =0.926*0.010 eV, EA(Pd2) = 1.685*0.008 eV, and EA(Pt,) = 1.898*0.008 eV. The electronic configurations of the ground states are tentatively assigned. Comparison of the nickel group dimers to the coinage metal dimers sheds light on the d orbital contribution to the metal bonding in the nickel group dimers.