Motion of light adatoms and molecules on the surface of few-layer graphene.

Low-voltage aberration-corrected transmission electron microscopy (TEM) is applied to investigate the feasibility of continuous electron beam cleaning of graphene and monitor the removal of residual species as present on few-layer graphene (FLG) surfaces. This combined approach allows us to detect light adatoms and evaluate their discontinuous sporadic motional behavior. Furthermore, the formation and dynamic behavior of isolated molecules on the FLG surface can be captured. The preferential source of adatoms and adsorbed molecules appeared to be carbonaceous clusters accumulated from residual solvents on the graphene surface. TEM image simulations provide potential detail on the observed molecular structures. Molecular dynamics simulations confirm the experimentally observed dynamics occurring on the energy scale imposed by the presence of the 80 kV electron beam and help elucidate the underlying mechanisms.