OPTICAL-PROPERTIES OF DOPED FULLERENES IN THE SUPERCONDUCTING STATE

The infrared optical conductivity of Rb3C60 and K3C60 and the temperat ure-dependent penetration depth of K3C60 are Calculated within a model for the pairing interaction which includes the possibility of couplin g to both intra- and intermolecular phonons. It is found that excellen t agreement with experimental data only occurs for coupling to high fr equency intramolecular phonons, with an impurity scattering rate in th e near-to-dirty limit. Strong coupling to low frequency modes is incom patible with the optical data.