Recombination of hydroxyl phases on Ag(110): coexistanece of long-range ordered domains of atomic oxygen and hydroxyl

We report on the thermal evolution of the OH-Ag(110) phase at coverage phi (OH)=0.66. Combined information, provided by thermal energy helium scattering and angle resolved ultraviolet photoemission spectroscopy, show that recombination of the OH sub gamma , sub-state, in the range 235-255K produces a new phase consisting of a mosaic of large and ordered oxygen domains and OH sub delta domains. The former present a (2 x 1) geometric structure with -Ag-O- added rows aligned along the < 001 > direction while the latter show a (1 x 2) structure with -OH-Ag- chains placed along the < 110 > direction. Further recombination of the OH sub delta sub-state starting around 260K and leading to the final O(3 x 1) phase around room temperature, proceeds through a continuous rearrangement between large ordered oxygen domains and OH disordered domains.