Far-infrared transmission of superconducting KxC60 films. (Reannouncement with new availability information)

Far-infrared transmission measurements have been performed on normal and superconducting KxC60 films on Si substrates. The films are prepared by thermal sublimation followed by in situ doping in a vacuum-tight cell. The observed peak in the ratio of the superconducting to normal transmittance near 50 cm{minus}1 is consistent with a distribution of superconducting gaps in the range (2-5)kTc.