INFLUENCE OF ADSORBED HYDROXYL AND CARBON-MONOXIDE ON POTENTIAL-INDUCED RECONSTRUCTION OF AU(100) AS EXAMINED BY SCANNING-TUNNELING-MICROSCOPY

The potential-dependent hexagonal (''hex'') reconstruction of ordered Au(100) in an alkaline electrolyte, 0.1M KOH, has been examined by means of in-situ scanning tunneling microscopy. In harmony with recent X-ray diffraction results, the hex --> (1 x 1) transition occurs at lower potentials, similar to 0 V versus SCE, than in weakly adsorbing acidic media such as perchloric acid, consistent with an influence of hydroxide adsorption. The dynamics of the reverse (1 x 1) --> hex transition accelerate markedly as the potential is lowered below about - 0.35 V versus SCE. Carbon monoxide adsorption, induced in 0.1M KOH at negative potentials, facilitates the formation of a notably homogeneous hex phase.