Undercover diffusion of atoms: Pb on Si(5 5 3)-Au surface covered by graphene

The diffusion of Pb atoms under a graphene layer deposited on a Si(5 5 3)-Au surface is studied by the first-principles density functional theory. The presence of graphene locks the moving Pb atoms inside tube-like closed objects, formed by grooves near steps of the Si(5 5 3)-Au surface and limited from the top by the graphene layer. As a result, the diffusion processes are well-separated from the environment. The methods of experimental verification of the undercover diffusion are also proposed.