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Abstract

The dynamic behavior of N atoms adsorbed on a Ru(0001) surface was studied by scanning tunneling microscopy. N atoms formed by dissociation of NO molecules show an initial sharp concentration profile at atomic steps. Its decay was followed as a function of time, providing a quasicontinuum diffusion constant; the activation energy is 0.94 eV and the prefactor is 2×10⁻²cm²s⁻¹. The diffusion constant was determined also at equilibrium, from statistical jumps of individual N atoms in a uniform overlayer, and is found to be identical to the Fickian value.