Optical response of cesium coated C-60

Photoabsorption spectra are reported for Cs and C60Csn+ clusters for n=40, 60, 120 and 310. The spectra were obtained by heating the mass selected clusters in a beam by means of photoabsorption until they evaporated metal atoms. The resulting mass loss was observed in a time-of-flight mass spectometer. The plasmon-like resonance in pure Cs clusters shifts to lower energies with decreasing cluster size. The collective electronic excitations in clusters containing C-60 are Split in energy as would be expected for fullerene molecules coated with layers of metal.