Sulfate superstructure

As an example, the ordered sulfate superstructure formed on Au(lll) in sulfuric acid at potentials wO.5 V higher than the potential of zero charge is shown in Fig. 2(a) [13], Although a unit cell can be assigned to this structure, in agreement with the coverage of 0.2 monolayers found in radiotracer and coulometric experiments [14], the precise composition of this structure is still unknown. This structure is only observed above a critical potential at lower potentials no ordered superstructure is observed. 

Figure 23.1. Network-like superstructure of a surfactant film of cetyltrimethylammonium bromide (c = 6 x 10 mol/1). The cross-linking process between the molecules was induced by adding multivalent counterions such as cerium sulfate c = 10 mol/1). The Brewster-angle image was obtained during the adsorption process of the amphiphilic molecules and represents the situation near the sol-gel transition, where the first infinite large clusters were formed. Black zones represent the pure water surface, while clear areas correspond to the presence of surfactant clusters...

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