Multilayers charge separation

In this context transannular interactions must be mentioned, although there are very few authenticated reports of such effects, and they involve solely sp2 carbon atoms. Thus, Maciel and Nakashima (256) ascribed a shielding of the carbonyl atom in 129 of approximately 10 ppm relative to 128 (X = CH2, O, S) to a transannular interaction associated with a partial charge separation (Scheme 40). Less clear-cut results were obtained from the spectra of 3- and 4-thiacyclohexanone (199,257). For the sake of completeness we note that aromatic carbon atoms experience considerable deshielding (6-9 ppm) in bi- and multilayered [2.2]paracyclophanes (258,259). This was attributed to a decrease of the excitation-energy term in the o-p expression (eq. [3], p. 222). 

Photochemically Induced Charge Separation in Electrostatically Constructed Organic-Inorganic Multilayer Composites... 

Sui, Z.J., Schlenoff, J.B. Phase separations in pH-responsive polyelectrolyte multilayers Charge extrusion versus charge expulsion. Langmuir 2W14, 20 (14), 6026—6031. 

Ninham, B.W. and Yaminsky, V., Ion binding and ion specificity the Hofmeister effect and Onsager and Lifshitz theories. Langmuir, 1997. 13(7) p. 2097-2108. Keller, S.W., et al., Photoinduced charge separation in multilayer thin films grown by sequential adsorption of polyelectrolytes. J Amer Chem Soc, 1995. 117(51) p. 12879-12880. 

Keller, S.W. et al., PhotochemicaUy induced charge separation in electrostatically constructed organic-inorganic multilayer composites, in Nocera D.G. and Wishart, J.S. Editors, Photochemistry and Radiation Chemistry Complementary Methods for the Study of Electron Transfer, 1998, Adv. Chem. Ser. 254 Photochemistry and Radiation Chemistry), p. 359-379. 

The most significant commercial product is barium titanate, BaTiO, used to produce the ceramic capacitors found in almost all electronic products. As electronic circuitry has been rniniaturized, demand has increased for capacitors that can store a high amount of charge in a relatively small volume. This demand led to the development of highly efficient multilayer ceramic capacitors. In these devices, several layers of ceramic, from 25—50 ]lni in thickness, are separated by even thinner layers of electrode metal. Each layer must be dense, free of pin-holes and flaws, and ideally consist of several uniform grains of fired ceramic. Manufacturers are trying to reduce the layer thickness to 10—12 ]lni. Conventionally prepared ceramic powders cannot meet the rigorous demands of these appHcations, therefore an emphasis has been placed on production of advanced powders by hydrothermal synthesis and other methods. 

---