Synthesis of fullerite (100) through epitaxy on a complex intermetallic surface
Résumé
We report the first epitaxial growth of bulk-like C60(100) plane stabilized by a size-matching effect on the surface of a complex intermetallic compound. As characterized by low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) techniques, the adsorption of C60 on Au-Si-Ho(100) surface is disordered at room temperature but ordered when the substrate is held at elevated temperature (669 K). In the submonolayer regime, different superstructures are observed depending on the fullerenes coverage. Upon completion of the first monolayer of C60, the thin film of c(1x1) superstructure is structurally equivalent to a (100) surface plane of the facecentered cubic structure of C60 bulk crystal. This structure is unusual for C60 monolayers on metal surfaces and appears to be favored by an almost perfect match between the most preferred C60 intermolecular distance and the distances separating specific adsorption sites of the large unit cell compound. The adsorption site selection is dictated by a local symmetry matching between the pentagonal fullerene facets and pseudo-five-fold symmetric atomic arrangements on the substrate. After the completion of the first monolayer, further deposition of C60 at 387 K results in the growth of a (100) oriented thicker epitaxial fullerite crystal.