Size-dependent dissociation of small cobalt clusters on ultrathin NaCl films

摘要

Mass-selected anionic cobalt clusters of two different sizes (Co_2 and Co_{13}) were deposited onto ultrathin NaCl films grown on an Au(111) substrate. Using scanning tunneling microscopy experiments and density functional theory simulations, we show that the deposited Co_2 cluster dissociates and that the resulting Co atoms dope the NaCl surface by substituting Na ions. In contrast, the larger Co_{13} cluster does not dissociate and remains stable on top of the NaCl film. The size-dependent fragmentation of clusters is an important aspect in the understandingof the chemical interaction between size-selected small aggregates of atoms and supporting surfaces.