Step fluctuations on Ag(110) surfaces have been investigated with STMT atomic events that underlie these thermal fluctuations are quantified using a Langevin analysis. From the t1- scaling of the step-position correlation function, we deduce random attachment and detachment processes along the step edge, with a characteristic interval of 350 ms between successive detachments.
Upon oxygen adsorption on vicinal Ag(110), a dramatic change in step configuration occurs. Steps which are originally equi-spaced due to repulsive step-step interactions are compressed into bunches. This process is driven by the formation of large (110) facets, on which oxygen atoms arrange into chains along . The faceting dynamics are sensitive to the orientation of the step edge: proceeding by nucleation for close-packed steps and by spinodal decomposition for steps at an acute angle to the oxygen chains.
A closer inspection of these oxygen chains reveals that each incorporates an additional row of silver atoms. When oxygen dosing pressures are kept below 10-6 Torr, silver atoms detaching from the step edge provide a sufficient supply necessary for the formation of the added row. With higher oxygen pressures, the silver atoms required for the oxygen chains are extracted directly from the terraces, resulting in the formation of large, long-lived etch pits.
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