Extraction of C60 cluster ion beam

A C+60 ion beam was extracted from a hollow cathode ion source (model 911A). The mass spectra of 6 keV C60 and its fragments have been measured. 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 beam has an exponential distribution, which is similar to that of C+60–H2(He) collision experiments. We also have extracted C-cluster negative-ion beams from a Middleton 860 sputtering source. With a graphite cathode, we have observed many cluster ions which were not previously reported. For a C60/C70 cathode, we have obtained a stable C−60 ion beam with current of about 1 nA. The spectra of the negative ions are complicated due to the existence of the Cs–Cn clusters.