Temporal evolution and nature of nanostructures on Au(111)

We have studied the nature of nanostructures and their time evolution on Au(111) created by argon ion irradiation followed by either subsequent or simultaneous annealing at different temperatures. For subsequently annealed surface, an initial linear decrease in the areas of the islands and pits is obtained with time. We show that the mass flow of the surface atoms is governed by the rate of detachment, rather than the rate of diffusion. The small islands and pits are found to disappear. In contrast, the areas of the large islands and pits initially decrease and become nearly constant as they attain a regular hexagonal shape. On the other hand, the simultaneously irradiated and annealed Au surface is much smoother with wide terraces and mostly pits of irregular hexagonal shape are observed. We also show that local stepped areas that resemble vicinal surfaces can form on Au(111) due to Ar ion irradiation.