DYNAMICS OF VACANCY ISLAND COALESCENCE ON AG(111)

The reshaping of two-dimensional vacancy islands during coalescence ha s been studied experimentally on a Ag(lll) surface at room temperature using a fast scanning tunneling microscope. Different stages of the c oalescence event have been found: the initial break-up of the narrow r egion separating the two islands (neck formation), the subsequent wide ning of the neck until an elongated shape has evolved, and the final r elaxation to the equilibrium shape, which is an equilateral hexagon wi th rounded corners. The relaxation time for reshaping is found to be a strong function of the island size: for coalescence events involving islands of a similar size it scales roughly with the third to fourth p ower of the island diameter. (C) 1998 Elsevier Science B.V. All rights reserved.