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RESEARCH PRODUCT

Holographic properties of azobenzene oligomers with differently bonded chromophore groups

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Holographic properties of two types (I and II, specified in the text) of azobenzene oligomers (ABO) have been experimentally studied in the spectral region of low absorption at 633 nm. In the case of type I ABO the chromophore groups were covalently bonded to either tolyl-polyurethane or hexamethylene-polyurethane matrix. In the case of type II ABO azobenzene chromophores were dispersed in polystyrene matrix, and their concentration was varied from 0.005 to 0.200 mol/l. Samples were in the form of 10 µm thick films. In both cases the diffraction efficiency exposure time dependences were measured for the holographic grating period of 2 (m at 633 nm. The diffraction efficiency of more than 2% and the specific recording energy down to 30 - 60 J/(cm2%) were achieved in both cases. In the case of type I ABO the best results were achieved with 4-nitronaphtylazobenzene chromophore groups in hexamethylene-polyurethane matrix. The chromophore concentration threshold within 0.01 – 0.04 mol/l range, the holographic efficiency growth with chromophore concentration and the photosensitization effect were found in the case of type II ABO. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)