KINETICS OF A POTENTIAL INDUCED 23X-ROOT-3 TO 1X1 TRANSITION OF AU(111) STUDIED BY INSITU SCANNING TUNNELING MICROSCOPY

A reversible transition between the 23 x square-root 3 and 1 x 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 x square-root 3 phase transforms to 1 x 1 as the surface potential is raised above approximately 440 mV (versus saturated calomel electrode), starting preferentially from step edges. The transition is reversed below approximately 240 mV. Extra atoms in the higher density 23 x square-root 3 phase can nucleate into monolayer Au clusters. The observed coexistence of phases and hysteresis indicate that the transition is first order.