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C60film has been grown heteroepitaxially on a cleaved face of MoS2by means of van der Waals epitaxy. The C60film forms a close-packed structure with its principal crystal axes parallel to those of the substrate. Although the lattice constant of the C60crystal is much larger than that of MoS2, good heteroepitaxial growth becomes possible because of the van der Waals-type interaction between the grown film and the substrate.

Vibrational spectra of C60and C70epitaxial films grown on cleaved surfaces of MoS2have been measured by high-resolution electron energy loss spectroscopy. In the case of C60, three intense dipole-active peaks were observed, which correspond to IR-active modes of C60under the specular reflection condition. In the case of C70, on the other hand, seven dipole-active peaks were found under the specular reflection condition only after annealing, which indicates that the flatness of the surface of the C70film was improved by annealing. The spectra of C60and C70under the off-specular reflection condition, which correspond to the vibrational densities of states of C60and C70molecules, resemble each other, indicating that the observed vibrational densities of states are characteristic of fullerenes.