CHARGE-TRANSFER IN ALKALI-METAL-DOPED POLYMERIC FULLERENES

We present room-temperature Raman measurements of pressure-polymerized C-60 and compare them with the spectra of RbC60 in the orthorhombic p hase. Although both materials were prepared according to two completel y different routes the spectra show a surprising similarity with respe ct to mode positions and line splitting. We concluded from this that b oth materials, the uncharged pressure-polymerized C-60 and the rubidiu m-doped orthorhombic compound, have the same overall structure and the AC(60) compounds can be considered as the doped species of the C-60, polymerized using moderate low pressure and high temperatures. From a detailed comparison between both spectra mode shifting and line broade ning as a consequence of the charge transfer was determined and electr on-phonon coupling constants were estimated for the high-frequency H-g (7) and H-g(8) modes. The low values for the coupling constants compar ed to the ones in the K3C60 can explain the lack of superconductivity in the AC(60) compounds.