Chromophores lattices

Clearly, a requirement for device quality second-order nonlinear optical materials is a noncentrosymmetric dipolar chromophore lattice. There are several ways by which such lattices have been achieved. With all methods, a force must... 

Note that no evidence of phase separation (second-order phase transition to a centric or antiferroelectric chromophore lattice) is found for conditions con-... 

B. Generation of Acentric Chromophore Lattices by Electric Field Poling... 

To satisfy device-related materials requirements, chromophores must exhibit large molecular hyperpolarizabilities and must be incorporated in Mgh number density into thermally stable acentric chromophore lattices defined by a high degree of chromophore order. Realization of approximately 10% of the potential macroscopic optical nonlinearity of a chromophore requires chromophore loading on the order of... 

Rutile pigments, prepared by dissolving chromophoric oxides in an oxidation state different from +4 in the mtile crystal lattice, have been described (25,26). To maintain the proper charge balance of the lattice, additional charge-compensating cations of different metal oxides also have to be dissolved in the mtile stmcture. Examples of such combinations are Ni " + Sb " in 1 2 ratio as NiO + Sb202, + Sb " in 1 1 ratio as Cr202 + Sb O, and Cr " +... 

In pigments, 2irconium sHicate serves as the host lattice for various chromophores, such as vanadium, praseodymium, iron, etc. Zirconium sHicate crystals are usuaHy formed in situ during pigment preparation by a high temperature reaction of Zr02 and Si02 ... 

Reinen and Grefer (116) have measured the d—d spectra of distorted tetrahedral Cu04 chromophores in mixed oxides. This work concerns copper-doped lattices such... 

Light Absorption by Surface-Located Chromophores Incorporating the Metal of the Oxice Lattice... 

Of more apparent significance in the aquatic environment are redox processes induced or enhanced on absorbance of light by chromophores at metal oxide surfaces in which the metal of the oxide lattice constitutes the cationic partner. Light induced electron transfer within such a chromophore often results in disruption of the oxide lattice. The photoredox-induced dissolution of iron and manganese oxides by such a mechanism has been proposed as a possible means of supply of essential trace-metal nutrients to plants and aquatic organisms (29-31). ... 

The presence of a covalent acyl-enzyme intermediate in the catalytic reaction of the serine proteases made this class of enzymes an attractive candidate for the initial attempt at using subzero temperatures to study an enzymatic mechanism. Elastase was chosen because it is easy to crystallize, diffracts to high resolution, has an active site which is accessible to small molecules diffusing through the crystal lattice, and is stable in high concentrations of cryoprotective solvents. The strategy used in the elastase experiment was to first determine in solution the exact conditions of temperature, organic solvent, and proton activity needed to stabilize an acyl-enzyme intermediate for sufficient time for X-ray data collection, and then to prepare the complex in the preformed, cooled crystal. Solution studies were carried out in the laboratory of Professor A. L. Fink, and were summarized in Section II,A,3. Briefly, it was shown that the chromophoric substrate -carbobenzoxy-L-alanyl-/>-nitrophenyl ester would react with elastase in both solution and in crystals in 70 30 methanol-water at pH 5.2 to form a productive covalent complex. These... 

Figure 5.32 Cross-linking and poling of NLO chromophore into a hardened lattice.

In violet (Fig. 34) and pink (Fig. 35) ultramarines, the lattice structure is little changed, but the sulfur chromophores are further oxidized, possibly to S3C1, S4, or S4. ... 

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