Silver-water interfaces

Among the many applications of LB films, the creation or arrangement of colloidal particles in these films is a unique one. On one hand, colloidal particles such as 10-nm silver sols stabilized by oleic acid can be spread at the air-water interface and LB deposited to create unique optical and electrooptical properties for devices [185]. 

The mechanism of Ca2+ binding is not clear yet. However, increase in repulsive double layer forces between neutral diacylphosphatidylcholine bilayer in aqueous media in the presence of divalent ions has been identified by other methods as well [293-296]. These systems differ from the foam- film model by virtue of their interface ordered lipid phase/water in place of the air/water interface of foam films. Nevertheless, the CaCb concentration where the transition from NBF to silver films is observed in experiments with foam films is very close to the concentrations where increase in the distance between the bilayers was found [293,294,296]. Results with microscopic films are also in good agreement with the established increase in the free energy of formation of macroscopic films stabilised with lysolecithin in the presence of CaCl2 [287]. 

Two other pieces of structural information can be derived from this scattering study. First, the molecules are oriented almost normal to the surface, cind second, the molecules adsorb with their hydrophobic moieties out of the water. This last feature is according to expectation and we have met this orientation before at water-silver iodide interfaces, see fig. II.3.77 (in sec. 11.3.12d). 

An advantage of surface-plasmon microscopy is that great contrast between layers of different thicknesses that can be obtained in very thin films without the use of the probe molecules. It is a requirement of the method, however, that there be an underlying coating of a conductor such as silver that carries that surface plasmon field. There is a possibility that images can be obtained from the water/monolayer film that adheres to a vertical slide that has been partially drawn through the air-water interface. ... 

FIG. 5 Approach curves for oxygen reduction at an inverted silver ultramicroelectrode approaching the air/water interface with a 1-octadecanol monolayer at the interface at different surface pressures Top to bottom, uncompressed, 5, 10, 20, 30, 40, and 50 mN/m. (From Ref. 28.)... 

In the simple GCSG model already described, the charge densities are assumed uniformly smeared over each plane rather than in the form of discrete ions. Levine and co-workers [8] modified the GCSG model by introducing the discreteness of charge effect to account for various phenomena, mostly relating to adsorption at the mercury/water and silver iodide/water interfaces. Their theory shows that the electrostatic work of adsorption at the IHP is not zet /p but... 

Ru(bipy)2 a nd pyrene. In all those cases no hack reaction between oxidized donor and Ag is observed. Apparently, through electrostatic interactions, the donor cation is ejected from the positively charge aggregates before back electron transfer can take place. Once in the aqueous phase, the reentry of in the micelle is prevented by the repulsive surface charge. We conclude that in the photoinduced reduction of Ag" " to silver atoms the fimctional macrocyclic surfactant serves three important purposes through high local concentration of the acceptor one accelerates drastically the forward rate - and hence the yield - of reaction the Ag atom is stabilized by the macro-cyclic ligand and finally, the back electron transfer prevented by the microscopic electrostatic barrier provided by the lipid/water interface. 

Chen, H., Jia, J., and Dong, S. (2007] Photochemical formation of silver and gold nanostructures at the air-water interface and their electrocatal5d ic properties. Nanotechnology, 18(24], 245601/1-8. 

Gordon J G, Melroy O R and Toney M F 1995 Structure of metal-electrolyte interfaces copper on gold(111), water on silver(111) Electrochim. Acta 40 3-8... 

Adsorption processes diagrammed, 266 Adsorption spectra of electrochromic polypyrrole, 363 Affinity for metal-water, 177 Air-solution interface, Nikitas on the potential of zero charge at, 30 Albury and Mount, interpretation of the semi-circle, 584 Alloys, potential of zero charge gold and silver, 142 tin and lead, 142 Kukk and Puttsepp on, 145 metals alloys, 141... 

Despite the fact that the electrodeposition of copper and silver at the water-DCE and the water-dichloromethane interfaces has been generally regarded as the first experimental evidence for heterogeneous ET at externally biased ITIES [171], a very limited amount of work has dealt with this type of process. This reaction has also theoretical interest because the molecular liquid-liquid interface can be seen as an ideal substrate for electrochemical nucleation studies due to the weak interactions between the interface and the newly formed phase and the lack of preferential nucleation sites always present at metallic electrodes. 

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