Giant fullerenes formed on C60 films irradiated with electrons field-emitted from scanning tunneling microscope tips

It has been found that spherical large clusters of carbon atoms are formed by irradiation of crystalline C60 films grown on Si(1 1 1)-(7 × 7) surfaces with electrons field-emitted from a scanning tunneling microscope probe tip. The size distribution of the clusters deduced from surface profile measurements suggests that the dominant clusters were not necessarily C60n (n = 2-4) expected from the simple fusion of C60 molecules. It was proposed that electronic excitations of C60 molecules caused the fragment and coalescence of the molecules to form the giant fullerenes as in the photo-induced similar effects.