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Hyperpolarizability in Multi-chromophoric Dipolar Dendrons Shiyoshi Yokoyama, Akira Otomo, and Shinro Mashiko Nonlinear optical dendritic macromolecules, called "azobenzene dendrons", having a branching structure modified with a second-order nonlinear optical chromophore has been synthesized. An electron donor and acceptor azobenzene chromophore having a large molecular hyperpolarizability of  0=150E-30 esu, was chosen. The electronic structure of synthesized dendrons, which were expected to become dipolar due to their intermolecular attractive interaction, was proven by second-order nonlienar optical properties. The molecular hyperpolarizabilities of azobenzene dendrons were measured by the hypr-Rayleigh scattering technique. The highest molecular hyperpoa1rizability was found to be 3,010E-30 esu for an azobenzene dendron having 15 chromophoric unit, where each chromophore coherently contribute to the second harmonic generation. This level of the molecular hyperpolarizability was much larger than that for a monomeric azobenzene chromophore.
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