Structure and Strain Field of Surface Dislocations on Gold Determined by Surface X-Ray Diffraction

Au(111) with its famous surface reconstruction has led to many studies, but its subsurface structure has never been determined. Here, we study the Au(677) surface which is a vicinal of Au(111) with steps and surface reconstruction, showing an array of surface dislocations. By using surface x-ray diffraction and atomistic simulations, we are able to quantitatively determine the complete structure and the strain fields associated with the surface reconstruction described in terms of surface dislocations, especially a stair-rod dislocation lying parallel to the surface step. The stair-rod dislocation strain field adds up to the one due to the step dipole, explaining the extraordinary regularity of the step array. We can also give new insights on the strain field associated with the Au(111) surface discommensuration lines (22×sqrt[3] reconstruction) and find that it penetrates deeply into the bulk, in contrast with commonly used surface reconstruction models.