A SCANNING-TUNNELING-MICROSCOPY STUDY OF FULLERENE FILMS

Atomic-scale and micro-scale images of C60 (fullerene) films using scanning tunnelling microscopy (STM) are presented. The atomic configuration of a C60 molecule has been clearly observed. Solvated fullerene molecules appear to pack in a hexagonal array on gold-coated freshly cleaved mica substrate, but they do not follow any long range order. STM images of ion-bombarded C60 films show that the bombarded films are smoother and possibly denser than the as-deposited films. Tribological tests on as-deposited and ion-bombarded films show that these films exhibit low friction and wear that are comparable to those of best known solid lubricants. STM images of a worn film (which has been rubbed against a steel ball) show that nearly spherical wear particles are formed which may roll in a sliding contact resulting in low friction and wear.