▎ 摘　　要

C-60 molecules adsorbed on graphene/Ru(0001) substrate were investigated by scanning tunneling microscopy (STM) at 5 K. On high quality substrates, C-60 molecules adopt a commensurate growth mode, leading to formation of a supramolecular structure with perfect periodicity and few defects. On under-annealed substrates with imperfections and domains, the molecules form the same closely packed hexagonal structures in spite of underlying corrugations, disorders or steps, indicating a weak molecule-substrate interaction-a conclusion that is also supported by DFT calculations. This system may be beneficial to the fabrication of carbon based devices and of other types of organic functional overlayers. (C) 2012 American Institute of Physics. [doi:10.1063/1.3673830]