MONOLAYER METAL COVERAGE OF FULLERENES - THE OPTICAL-RESPONSE

A first-principles investigation of the photoabsorption cross section of the specially stable cluster Li12C60 is carried out, including the icosahedral symmetry of the cluster and treating the ions via ab initi o pseudopotentials. The role of the coating metal is assessed by compu ting the same quantity for the fullerene ''seed''. It is found that th e main absorption features are determined by the carbon molecule, both at low and high excitation energies, in spite of a reduction of 60% f or the ionization threshold of Li12C60 as compared to C-60. Nonetheles s the lithium coating is responsible for small yet clearly observable effects throughout the spectrum, in particular for a more structured a nd broad strength distribution at excitation energies below the ioniza tion threshold of C-60, and a double peak structure in the Mie resonan ce at approximate to 20 eV.