It was pointed out that adatoms which moved over the substrate surface under a scanning tunnelling microscope tip led to a random time dependence of the current. Simple expressions were deduced for the average current and the temporary current correlation from the diffusion coefficients of adatoms and from a few parameters for the tunnelling gap. The results suggested that it was possible to deduce the local diffusivity of adatoms from experimentally measured current dependences.

M.Sumetskii, A.A.Kornyshev, U.Stimming: Surface Science, 1994, 307-309, 23-7