Abstract
The diffusion has been measured by observing the profile of silver coverage with scanning AES. Close to theta =0.25 (saturation of the 4*2 superstructure) the diffusion coefficient has a sharp maximum. This peak is explained by a change of the binding energy with changing superstructure. The activation energy for diffusion and the prefactor also show an anomaly at the critical coverage. Moreover the diffusion has been measured on faces with anomaly at the critical coverage. Moreover the diffusion has been measured on faces with different step densities. The results show an increase of the diffusion coefficient of about a factor of 100 along the steps compared with the diffusivity on a smooth (111) face. The FWHM of the superstructure LEED spots allows a direct observation of the growth of the square root 3-R 30 degrees domains. The growth on the 4*2 layer proceeds with the tenth root of time. This time dependence may indicate dissolving of small islands in favour of large ones.