Helium atom diffraction was used to study the reconstruction kinetics of a stepped metallic surface, Ni(977), which sequentially underwent step-doubling and -singling upon dosing with low coverages of oxygen. At 390 to 470K, it was found that less than 2% of a monolayer of oxygen was sufficient to transform the initially prepared single-stepped surface to a new steady state having a double-stepped structure. The thermal range over which the doubled phase exists extended to higher temperatures when more oxygen was present. At low oxygen exposures this doubled interface reverted to the single-stepped surface above 470K. Singling could also be driven by more extensive levels of oxygen adsorption. The kinetics of the step-doubling transformation which occurred below 470K was determined to be second order with respect to single-step density while, at above 470K, step-singling obeyed first-order kinetics with respect to the double-step density. Oxygen atoms adsorbed at step edges play a crucial role in these transformations. An Arrhenius analysis was used to extract energetics for the step-doubling and -singling reconstructions. The results delineated the sequence of mechanistic stages which occurred during the initial stages of oxidation of a stepped metallic interface which preceded the onset of bulk oxidation.

Reconstruction Kinetics of a Stepped Metallic Surface - Step Doubling and Singling of Ni(977) Induced by Low Oxygen Coverages. L.Niu, D.D.Koleske, D.J.Gaspar, S.F.King, S.J.Sibener: Surface Science, 1996, 356[1-3], 144-60