Kinetics of a potential induced 23 × 3 to 1 × 1 transition of Au(111) studied by in situ scanning tunneling microscopy

A reversible transition between the 23 × 3 and 1 × 1 phases of Au(111) under HClO₄ was observed by scanning tunneling microscopy and its dynamics studied on time scales between tens of seconds and hours. The 23 × √3 phase transforms to 1 × 1 as the surface potential is raised above ∼ 440 mV (versus saturated calomel electrode), starting preferentially from step edges. The transition is reversed below ∼ 240 mV. Extra atoms in the higher density 23 × 3 phase can nucleate into monolayer Au clusters. The observed coexistence of phases and hysteresis indicate that the transition is first order.