Kinetics of oxygen-induced faceting of vicinal Ag(110)

The oxygen-induced breakup of vicinal Ag(110) facets and step bunches were measured with scanning tunneling microscopy. Faceting occurred at oxygen coverages less than that of the (7x1) reconstruction. Faceting transitions were recorded in real time at room temperature for two surface orientations. The nature of the faceting transition was found to be sensitive to surface orientation. A vicinal Ag(110) surface, comprised of 35 A wide terraces, separated by close-packed steps facets slowly by nucleation. This surface misoriented by 2 deg towards [001] facets through the growth of isolated nuclei. Step-position fluctuations of increasing magnitudes were observed prior to faceting, revealing a critical terrace width of approx100 A. In contrast, oxygen exposure caused Ag(110), misoriented by 2 deg towards [331], to facet spontaneously with no evident nucleation barrier.