Oscillatory adatom-adatom interactions of ID and 2D surface diffusion systems

Direct observations with the field ion microscope make it possible to determine the probability P(R) of finding two atoms on a surface at a separation R at equilibrium at temperature T. The free energy of interaction F(R) can be obtained from the relation: P(R) ∝ exp[-F(R)/kT]. For the ID diffusion system, the interactions of two Pd atoms on the W(211) plane are studied for following cases: two Pd atoms in the same, and in the nearest channels. Oscillatory behaviors of these interactions along the channel direction are observed and analyzed with data fitting. For the 2D diffusion system, the interactions of two W atoms on the Ir(111) plane are studied. The oscillatory behaviors are not only observed in the interaction energy versus adsorbate separation curve, but also along the [2, -1, -1] and [-1, 0, 1] axes. The interaction energy of the different systems and cases is discussed.