Brillouin-scattering determination of the elastic constants of epitaxial fcc C60 film

Brillouin-light-scattering measurements have been performed on a (111) fcc film of C60 (fullerite) epitaxially grown on Ni(110). The Rayleigh surface wave has been detected for propagation along several directions on the film surface and shows an anisotropic behavior consistent with the (111) texture of the film. Bulk acoustic modes have also been measured. The Brillouin data allow the determination of the three independent elastic constants of fcc C60. The breakdown of the Cauchy condition indicates intermolecular interactions of non- central character.