Dynamics of the artificially created vacancies in the monomolecular C60 layers

Dynamics of single and double vacancies within the monomolecular C60 layer on the In-modified Au/Si(111) 3×3 surface have been studied by means of variable temperature scanning tunneling microscopy (STM). The vacancies were deliberately created in the layer using STM tip impact in the regimes below decomposition threshold. Single vacancy motion has been found to be a thermally activated process characterized by the activation energy of 1.5 ± 0.3 eV. This is an effective activation energy which agrees with the net value consisted of the term responsible for vacancy migration within the free-standing C60 layer, 0.88 eV and that for individual C60 migration on (Au, In)/Si(111) surface, ~ 0.4 eV. Mobility of C60 vacancies has been found to be affected by In adatoms. It can be slowed down by more than an order of magnitude by deposition of only 0.2 monolayer of additional In. The double vacancies have been found to be more mobile than single vacancies in which its effect is provided by a specific rotational mechanism of their motion.