A photosensitive material based on photo-induced polymerization has been used to record holograms. Exposure of 1 to 30 mJ/cm2 at 0.694 μ were followed by rapid optical, dry processing with ultraviolet radiation. Good resolution and diffraction efficiencies of up to 45% into the first order were observed.

These studies characterize the primary process and products in the photodecarboxylation of nitrophenylacetate ions in aqueous solutions. 3-Nitrophenylacetate, 4-nitrophenylacetate, and 4-nitrohomophthalate ions decarboxylate with a quantum yield of about 0.6 at 367 nm, while that of o-nitro structures (2-nitrophenylacetate and 2,4-dinitrophenylacetate ions) is only 0.04. acz'-Nitro intermediates are identified spectrally by flash photolyses from the o-and p-nitro structures, but not from the m-nitro structure. Results are consistent with a mechanism of photodecomposition into carbon dioxide and a nitrobenzyl anion which is stabilized as an ««-nitro anion in o-and p-nitro structures. The nitrophenylacetic acids are more stable photochemically than their ions; neither C02 nor a«'-nitro intermediates are observed from photolysis of the undissociated acids. The ««-nitro yield varies with pH according to the pA-of the acid being photolyzed; thus a pK of 4.8 is calculated for the acarboxyl group of 4-nitrohomophthalic acid. Three of the ««'-nitro anions occur via photochemical hydrogentransfer reactions from other compounds so that by comparison with the photodecarboxylations the quantum yields of H-transfer photochromism in 2-nitrotoluene, 2,4-dinitrotoluene, and 5-nitro-otoluate ions are estimated to be about 0.01, 0.003, and 0.07, respectively.In the course of studies on the photochromism of compounds with nitrobenzyl structures,1 we noted that an irreversible photochemical decarboxylation occurs in aqueous solutions of compounds with nitrophenylacetate ion structures.2 In both types of reaction '-nitro intermediates are postulated to occur from photochemical acid-base processes. While the photochromic process appears to be a reversible proton-transfer reaction, the photodecarboxylation mechanism is based upon the formation of carbon dioxide and a carbanion residue, as in eq 1. The carboxyl forms of these nitrophenylacetic acids photodecompose less readily and do not yield the same intermediates or products as their ions.

The birefringence of two common nematic liquid crystals were measured in the millimeter wave range, and were found to be in the range of 0.19–0.22 at room temperature. Using liquid crystal electro- and magneto-optical effects, we present the first experimental data of a novel liquid crystal millimeter wave electronic phase shifter. Our experiments show that liquid crystals could play an important role in future millimeter wave device technologies.

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Thirty new asymmetric diphenyl-diacetylene (PTTP) liquid-crystal homologs are synthesized and their physical properties characterized. In addition to the observed high birefringence and relatively low viscosity, several dialkyl PTTP homologs also possess a low melting point, wide nematic range, and low heat of fusion enthalpy. These properties are highly desirable for forming eutectic mixtures with entirely PTTP components. A binary eutectic showing a nematic range from 10 to 98 °C is studied. These new liquid-crystal compounds and mixtures should be particularly useful for infrared applications.

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