Structural and Magnetic Properties of CoGen- (n=2-11) Clusters: Photoelectron Spectroscopy and Density Functional Calculations

A series of cobalt-doped germanium clusters, CoGen-/0 (n = 2-11), are investigated by using anion photoelectron spectroscopy combined with density functional theory calculations. For both anionic and neutral CoGen (n = 2-11) clusters, the critical size of the transition from exo- to endohedral structures is n = 9. Natural population analysis shows that there is electron transfer from the Ge-n framework to the Co atom at n = 7-11 for both anionic and neutral CoGen clusters. The magnetic moments of the anionic and neutral CoGen clusters decrease to the lowest values at n = 10 and 11. The transfer of electrons from the Ge-n framework to the Co atom and the minimization of the magnetic moments are related to the evolution of CoGen structures from exo- to endohedral.