Frictional and atomic-scale study of C60 thin films by scanning force microscopy

Scanning force microscopy (SFM) was employed to characterize C60 island films in an ultra-high vacuum (UHV). The initial growth stage of C60 on NaCl cleavage faces and nanotribological properties of this solid lubricant are investigated. In comparison to the NaCl(001) face, higher friction is measured on the C60 islands, resulting in a ratio of friction of 1:3 for NaCl:C60. The friction coefficient of the (111) oriented C60 island is determined to be 0.15+/-0.05. High-resolution SFM images reveal the hexagonal lattice of the unreconstructed (111) top surfaces and the overgrowth relationships of the C60 islands.