(regions are marked with arrows in Fig. ). In the region where the film exfoliated (Fig. ), the surface seems significantly restructured. In Fig. , where the film is still more or less intact, the porosity of the NPG film is very much different on the Au(111) terraces (bright region) than in the region which connects these terraces (dark region). In the Au(100*) region in Figs. and, exfoliation of the film is usually not observed. However, here we also observe a difference in the NPG film structure depending on the region on the Au(100*) facet. Unlike the Au(111*) facet, the NPG film structure is not different for the Au(100) terraces and the adjacent step edges, but the NPG film breaks up randomly between them. In the brighter areas, the NPG film is less dense or seems slightly torn apart. Figure ' shows a magnification of the homogeneous NPG region in Fig. , i.e., of the region where the NPG film is rather compact. Figure " shows a region of the NPG film that is less compact. The two regions in Figs. and" are marked in Fig. . Overall, the NPG film obtained on the Au(100*) facet is clearly more homogeneous than the one formed on the Au(111*) facet. As in the case of Au oxide formation, grain boundaries have no influence on the structural properties of the NPG films at 540 V as illustrated in Fig. . The structure of the NPG film formed after 4 s on the Au(111*) facet in Figs. and, is very similar to that obtained after 2 s. Thus, a homogeneous NPG film forms on the Au(111) terraces, which is torn apart in the regions between these terraces apparent from Fig. . On the Au(100*) facet in Figs. and, the NPG film is still homogeneous, showing similar structures on the terraces and the regions in between. Only in a few cases, we observed that the film was slightly torn apart at the regions vicinal to the Au(100) facet, as shown in Fig. . After 15 s and 30 s, from the microscopy and SEM images (see Fig. and Fig. ), the NPG film on the Au surface is rather irregular and inhomogeneous on the entire bead. After both electrolysis times, the NPG film significantly exfoliates from the Au(111) facet as shown in Figs. and. Interestingly, from a closer inspection of the individual facets shown in Figs. 9i to l, one observes that the NPG film on the Au(111*) facet is rather homogeneous in contrast to shorter electrolysis times, where the NPG films are much thinner (according to the electrochemical data presented in Fig. ). On the Au(100*) facet, the situation is different (see Figs. and). After 30 s, the NPG film is torn apart, though it does not exfoliate. This suggests strong interaction of the NPG film with the substrate. On the Au(100) facet, the NPG film is homogeneous, and almost no cracks were observed within the film (see Fig. ).