Nanostructure formation by reactions of H2O with pre-adsorbed O on a Ag(1 1 0) surface

We present results of an STM investigation of water interaction with an oxygen covered Ag(1 1 0) in the case of the O(4 × 1) reconstructed surface. Regarding the formation of one-layer-thick silver nanostructures previously demonstrated, they point to the key role of the surface temperature at which the water dosing is made. Indeed we measure silver nanostructuring for dosing temperatures lower than 235 K. We follow, in real time during the water dosing, the modifications induced at the surface for two temperatures of 200 K and 240 K. Drastic differences are exhibited. At 200 K, after an initial stage of formation of molecular assembly strips along the [0 0 1], the reactive process leading to the conversion to an OH layer occurs clearly going along with the appearance and development of quasi-rectangular silver nanostructures. At 240 K, no such initial phase is evidenced. The complete conversion to an OH row structure of the scanned area occurs with no concomitant silver nanostructure formation. The dynamical behaviour of the reaction front allows the unravelling of the key role of the developing OH row ends intersecting the remaining Ag–O rows as particular reactive adsorption sites for the completion of the OH layer.