Anomalous 13 422 diffraction spots from {111} flat gold crystallites: (111) surface reconstruction and moiré fringes between the surface and the bulk

This paper describes very flat {111} gold crystallites grown on graphite. The diffraction patterns of such crystallites show the “usual” $\text{1}\text{3}$ 422 anomalous spots. It is shown that these spots are in fact split in such a way that each $\text{1}\text{3}$ 422 spot is surrounded by an hexagonal array of additional spots, aligned in the 〈110〉 directions. When seen by TEM, the crystallites show 〈112〉 periodic contrasts which are not normal moiré fringes or misfit dislocations between gold and graphite. An interpretation following Yagi et al. is proposed which connects these 2 kinds of anomalies: they should result from the surface superstructure 23 × 1 of clean (111) gold face, described very recently by Melle and Menzel.