FORMATION AND COALESCENCE OF FULLERENE IONS FROM DIRECT LASER VAPORIZATION

A series of carbon cluster ions have been created by direct laser vapo rization of elementary carbons and organic compounds with different st ructures and compositions. The mass spectra of the carbon cluster ions were recorded in situ by a time-of-flight mass spectrometer and the e xperimental results showed that the formation of fullerenes and their relative abundances are closely related to the surface structure of th e sample. Under direct laser vaporization, the products from a perfect (0001) surface of graphite were mainly C-60 and C-70. The surface per pendicular to the (0001) plane of graphite could not produce C-60, oth er fullerene ions or compounds containing six-membered aromatic carbon rings. The products of amorphous carbon and aromatic compounds includ ed C-60 and other fullerenes, among which those with a mass twice that of C-60 were most abundant. Furthermore, C-60 and C-70 could also be aggregated from direct laser vaporization. Based on these experimental results, mechanism for formation of C-60 and other fullerenes is sugg ested.