Oligo nonlinear optics

Geisler, T. Pedersen, K. Petersen, J. C. Third-harmonic Generation in Substituted Oligo-phenylene Vinylenes and Organic Square Planar Nickel Complexes. In Notions and Perspectives of Nonlinear Optics Keller, O., Eds. World Scientific Singapore, 1996 pp 580-585. 

Poly- and oligo(a-thiophene) derivatives are important compounds for biological studies, electronic semiconducting materials, nonlinear optical materials, and highly ordered molecular assemblies. 

Electrostatic self-assembly was combined with supramolecular chemistry to obtain inclusion complexes of a polymeric nonlinear optical (NLO) active dye and modified [3-cyclodextrin with induced chromophore orientation [37], The polyanion is a N,N-diallyl-aniline and sodium-2-acrylamido-2-methylpropanesulfonate copolymer functionalized with pendant azo group. The modified /i-cyclodextrin oligo-cation was obtained by treatment of hcptakis(6-dco y-6-iodo-/i-cyclodcxtrin) with excess pyridine. A linear polyamine, chitosan, was also combined with the polyanion, for comparison. Films were deposited on glass slides by dipping them alternatively in aqueous solutions of the cation and the polyanion. UV-visible spectra indicate dye aggregation and suggest the formation of an inclusion complex of the dye with the cyclodextrin, thus isolating the chromophores. 

Optical tuning of polygermanes and mixed polysi-lane/polygermane systems have been discussed.Nonlinear optical effects are of particular interest. Third-order nonlinear susceptibilities (/ ) for thin films of oligo- and polygermanes have been measured.A value of 86 x 10 esu was obtained for copoly(methyl-phenylsilylene/methylphenylgermylene)... 

Kimura, et al. synthesized polymers bearing oligo-aromatic esters as side chains to form second-order nonlinear optical active polymers on the basis of architecture. The cut-off wavelength ( co) of these polymers is shorter than the visible region, i.e., kco ca. 330-370 nm, which are much shorter than the typical second order nonlinear optics polymer containing chromophores like azobenzene. These polymer films exhibit good transparency in the visible region. The second-order nonlinear optical coefficient, is 2.2-9.S pm.V... 

A simple model describes the linear and nonlinear optical properties of conjugated polymers [e.g., oligo(thiophene)s] found from the measurements of the optical band gap of two oligomers of different length, without the need for supercomputing power [409]. Photocatalytic CO2 fixation is observed in photoirradiation experiments on a PAT film immersed in ethanol solution containing 4-butylphenol in a CO2 atmosphere [367,368]. An electric field induces changes in the optical properties of PATs and poly(thienylene vinylenejs. The induced absorption is proportional to the square of the applied electric field and its line shape is field invariant [410]. 

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