EXTRACTION OF C60 CLUSTER ION-BEAM

A C60+ ion beam was extracted from a hollow cathode ion source (model 91 IA). The mass spectra of 6 keV C60 and its fragments have been meas ured. Only those clusters with an even number of C atoms were observed and the largest one was C84. The result shows that the fragment ion b eam has an exponential distribution, which is similar to that of C60+- H2(He) collision experiments. We also have extracted C-cluster negativ e-ion beams from a Middleton 860 sputtering source. With a graphite ca thode, we have observed many cluster ions which were not previously re ported. For a C60/C70 cathode, we have obtained a stable C60- ion beam with current of about 1 nA. The spectra of the negative ions are comp licated due to the existence of the Cs-C(n) clusters.