Probing the electronic structure of small iron clusters

The electronic structure of small iron clusters is probed with size-selected anion photoelectron spectroscopy. The photoelectron spectra for Fe9− to Fe16− exhibit consistently sharp features near the threshold and their spectral changes correlate well with changes of their chemical reactivity. Extended Hückel calculations, based on body centered cubic structures for Fe9 to Fe16, provide a reasonable explanation of the experiment. These calculations also yield insights into the cluster magnetism and allow an interpretation of the cluster chemical reactivity based on their electronic structure.