Electronic structure of pristine and intercalated Sc3N@C80 metallofullerene

Abstract

We report a study of the electronic structure and charge transfer in the metallofullerene Sc3N@C80 using photoemission and x-ray absorption spectroscopy. Through a comparison of the x-ray absorption spectrum of Sc3N@C80 at the Sc L2,3 edge with atomic multiplet calculations, the Sc 3d electron count is determined to be 0.6, thus giving an effective Sc valency of 2.4. With the N atom gaining a full electronic shell by means of covalent bonding with the Sc (also involving the Sc 3d electron density observed in the x-ray absorption experiments), the remaining six valence electrons of the Sc3N cluster are then transferred to the carbon cage which stabilizes the C80 cage structure with Ih symmetry, a structure which is not energetically favored in neutral C80. The presence of the highly symmetric Ih cage structure is further supported by the observation of distinct fine structure in the valence band photoemission spectra of the endohedral, which results from the high degree of effective degeneracy of the electronic states in the molecule. Finally, the results of investigations of K-doped Sc3N@C80 using photoemission give insight into the KxSc3N@C80 phases that are formed upon intercalation.