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An internal or external electric field F can drive the chemical structure, bond order afternation, and electronic structure of linear polymethine dyes from a neutral bond-alternated, polyene-like structure, through a cyanine-like structure, and ultimately to a zwitterionic (charge-separated) bond-alternated structure. As the structure evolves under the influence of F, the linear polarizability α, the first hyperpolarizability β, and the second hyperpolarizability γ are seen to be derivatives, with respect to F, of their next or order polarization (for α) or polarizability (for β and γ). These derivative relations provide a unified picture of the dependence of the polarizability and hyperpolarizabilities on the structure in linear polymethine dyes. In addition, they allow for predictions of structure-property relations of higher order hyperpolarizabilities., Since the discovery of synthetic dyes in the 1800s, chemists and physicists have been attempting to understand the relation between chemical structure, electronic structure[1-3], linear optical properties, and linear polarizability [...]

Conjugated organic molecules were used to develop a computational technique to examine the relationship of polarizability (alpha) geometry, molecular dipole moment (mu), change separation and hyperpolarizabilities (beta, gamma). A major structurally significant parameter that can be correlated with hyperpolarizabilities and which is crucial to the optimization of materials and moelcules is bond-length modification.

The solvent dependence of the second hyperpolarizability, γ, of a variety of unsaturated organic compounds has been measured by third harmonic generation at 1907 nanometers. iIt is seen that the measured γ is a function of solvent polarity. These solvent-dependent hyperpolarizabilities are associated with changes in molecular geometry from a highly bond-length alternated, polyene-like structure for a formyl-substituted compound in nonpolar solvents, to a cyanine-like structure, with little bond-length alternation, for a dicyanovinyl-substituted compound in polar solvents. By tuning bond-length alternation, γ can be optimized in either a positive or negative sense for polymethine dyes of a given conjugation length., The development of materials with third-rder optical nonlinearities has been the focus of much recent research[1, 2].Such materials are of interest for a variety of optical switching and processing applications. [...]

Thin Films of [n-Si/Poly-(CH.sub.3).sub.3.Si-Cyclooctatetraene:] Conducting-Polymer Solar Cells and Layered Structures ELECTRONICALLY CONDUCTIVE POLYMERS are currently of interest for their possible applications in electronics [1], nonlinear optics [2], and solar energy [...]

Platinum black efficiently catalyzes the oxidation of methane by iron(III) to generate carbon dioxide and eight equivalents of iron (II) in solutions of sulfuric acid in water. The rate of oxidation increases over 4 hours to reach -4.83 x [10.sup.-2] moles of iron(II) per gram atom of surface platinum per second. A redox fuel cell was assembled that used this reaction in a liquid reformer to generate soluble reducing equivalents of iron(II) from methane, which was electrochemically oxidized to iron(ill) in the cell. A vanadium(V)-(IV)-nitric acid-[O.sub.2] redox system catalyzed the electrochemical reduction of [O.sub.2]. The open-circuit voltage of the cell was 0.48 volt, and the maximum power output of the cell was 8.1 milliwatts per cubic centimeter of graphite felt electrode., We have operated a redox fuel cell with methane as fuel at 120°C in which graphite felt was used as the anode and cathode. Methane is presently the most abundant [...]

Author(s): Christopher Gorman (corresponding author) [1] The long chains of molecules that make up a polymer tend to be arranged in a linear way, often resembling lengthy, tangled strips of [...]