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

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