Electronic and vibrational structure of transition metal trimers: Photoelectron spectra of Ni−3, Pd−3, and Pt−3

Abstract
The transition metal trimer anions Ni3, Pd3, and Pt3 are prepared in a flowing afterglow ion source with a cold cathode dc discharge. The low‐lying electronic states of the neutral trimers are probed by 488 nm negative ion photoelectron spectroscopy at an electron kinetic energy resolution of 5–12 meV. Each trimer exhibits multiple low‐lying electronic states. Vibrational progressions are observed in tripalladium and triplatinum. The adiabatic electron affinities are found to be EA(Ni3)=1.41±0.05 eV, EA(Pd3)≲1.5±0.1 eV, and EA (Pt3)=1.87±0.02 eV.