Energetics of the manganese trimer and tetramer ions

Abstract

The photodissociation processes of the manganese cluster ions Mnn+ (n=3 and 4) were investigated in the visible and near-infrared photon-energy ranges. The threshold energies were determined for the two-atom-loss channels by measurements of the spectra of the partial photodissociation cross sections. The binding energies of Mnn+ (n=3 and 4) were obtained by using these threshold energies and the known bond dissociation energy of Mn2+. The bond dissociation energies of Mn3+, D0(Mn2+⋯Mn), and Mn4+, D0(Mn3+⋯Mn), were determined to be 0.83±0.05 and 1.04±0.07 eV, respectively. Thus the binding energies (per atom) of Mn3+ and Mn4+ turned out to be 0.74±0.03 and 0.82±0.05 eV, respectively. These findings show that the interaction between manganese atoms is exceptionally weak, compared with other transition-metal cluster ions.