THRESHOLD HEIGHT FOR MOVEMENT OF C-60 MOLECULES ON SI(111)-7X7 WITH ASCANNING TUNNELING MICROSCOPE

Scanning tunneling microscope has been employed for intentional moveme nt of C60 molecules adsorbed on Si(111)-7 X 7 surface. Threshold condi tions at which a C60 molecule starts moving from its adsorption site a re investigated in relation to tunnel current and tip bias voltage. We find that there exists threshold height for the movement process. The threshold height estimated from a planar electrode model is in agreem ent with the vertical height of the adsorbed C60 molecules. Present re sults evidence that direct contact or close proximity between a mechan ical probe and C60 molecules is required for movement of the molecules to occur.