Mono-layer regime

Figure 5-19. N(ls) XPS core level spectra of emeraldine base adsorbed on ITO. The top most spectrum corresponds to ultra-thin Him (in the mono layer regime) while the bottom spectrum corresponds to thick film.

In the present chapter we will summarize results of two different evaluation procedures for the surface roughness of carbon blacks. In the mono-layer regime we refer to the scaling behavior of the estimated BET-surface area with the size of adsorbed probe molecules (yardstick method). On smooth flat surfaces the BET-area is independent of the adsorbed probe or applied yardstick, while on rough surfaces it decreases with increasing probe (yardstick) size due to the inability of the large molecules to explore smaller cavities. This is shown schematically in Fig. 5. 

Copper electrodeposition on Au(111) Copper is an interesting metal and has been widely investigated in electrodeposition studies from aqueous solutions. There are numerous publications in the literature on this topic. Furthermore, technical processes to produce Cu interconnects on microchips have been established in aqueous solutions. In general, the quality of the deposits is strongly influenced by the bath composition. On the nanometer scale, one finds different superstmctures in the underpotential deposition regime if different counter-ions are used in the solutions. A co-adsorption between the metal atoms and the anions has been reported. In the underpotential regime, before the bulk deposition begins, one Cu mono-layer forms on Au(lll) [66]. 

Perylene-tetracarboxylicacid-dianhydride (PTCDA) is among the most thoroughly studied organie semieonduetors [20-22, 72-84], both in the mono-layer and multilayer regime. 

For Pd on Ni(l 11) a moire pattern is found at a coverage of 2 ML [48], which is also present for Ag on Cu(l 11) in the monolayer regime at 150 K deposition temperature. In this case, however, a triangular pattern is found if the deposition is done at RT [49-51 ]. A similar case is present for a Au mono-layer on Ni(l 11). At 170 K deposition temperature a rotated moire pattern is found while annealing at 400 K or deposition at RT results in the formation of a triangular structure [52]. 

Given the size of clay particles (10-1,000 nm), they are found in solution as colloidal dispersions or gels. At low water content, they can be obtained as dry powders, and can form solid porous materials upon compaction. In all these regimes, their properties crucially depend on the charge density and on the nature of the counterions. Most counterions are mono- or divalent, usually alkaline (most commonly sodium Na" or potassium or alkaline earth cations (most commonly calcium Ca " ). They are not incorporated in the clay layers. Rather, they are located near the surface, either between different layers, in the so-called interlayer porosity, or on the external surfaces of clay stacks (typically 10 layers). Such stacks are called particles, and their assembly to form a porous material then leaves voids called interparticle porosity, with sizes between a few nanometers to tens of nanometers, which are usually saturated by an electrolyte solution. 

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