Electronic structure of pristine and intercalated Sc3N@C80 metallofullerene -: art. no. 035107

We report a study of the electronic structure and charge transfer in the metallofullerene Sc3N@C-80 using photoemission and x-ray absorption spectroscopy. Through a comparison of the x-ray absorption spectrum of Sc3N@C-80 at the Sc L-2,L-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 C-80 cage structure with I-h symmetry, a structure which is not energetically favored in neutral C-80. The presence of the highly symmetric I-h 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@C-80 using photoemission give insight into the KxSc3N@C-80 phases that are formed upon intercalation.