THE ELECTRONIC-STRUCTURE OF POLYMERIZED FULLERENES AND DIMERIZED HETEROFULLERENES

We present studies of the electronic structure of polymerized orthorho mbic Rb1C60 and dimerised C59N using electron energy-loss spectroscopy in transmission. From the C(1)s excitation spectra a reduced density of pi states is observed for polymerized Rb1C60 This is in contrast t o (C59N)(2) and can be explained by the different type of 'doping' and by the different bonding between the fullerene molecules in the two s ystems. Additional information about the optical properties was obtain ed from the low energy loss function. Using a Kramers-Kronig analysis, the dielectric function, (epsilon), and the optical conductivity, (si gma), have been derived. epsilon(0) and the onset of the spectral weig ht have been compared between the polymer, the dimer and C-60 This ons et of spectral weight is found to be at 1.2 and 1.4 eV for o-Rb1C60 an d for (C59N)(2), respectively.