The manipulation of C60 in molecular arrays with an STM tip in regimes below the decomposition threshold

Abstract

The ability of scanning tunneling microscopy to manipulate selected C60 molecules within close packed C60 arrays on a (Au,In)/Si(111) surface has been examined for mild conditions below the decomposition threshold. It has been found that knockout of the chosen C60 molecule (i.e., vacancy formation) and shifting of the C60 molecule to the neighboring vacant site (if available) can be conducted for wide ranges of bias voltages (from −1.5 to +0.5 V), characteristic manipulation currents (from 0.02 to 100 nA) and powers (from 2 × 10−8 to 0.1 μW). This result implies that the manipulation is not associated with the electrical effects but rather has a purely mechanical origin. The main requirement for successful C60 knockout has been found to be to ensure a proper ‘impact parameter’ (deviation from central impact on the C60 sphere by the tip apex), which should be less than ∼1.5 Å. A certain difference has been detected for the manipulation of C60 in extended molecular arrays and molecular islands of a limited size. While it is possible to manipulate a single C60 molecule in an array, in the case of a C60 island it appears difficult to manipulate a given fullerene without affecting the other ones constituting the island.