联苯衍生物的光折变效应

Abstract

The photorefractive phenomenon was observed in biphenyl derivatives materials under continuous wave laser(532nm) irradiation. Two types of sample were prepared:biphenyl derivatives(2-(4-hydroxypheny)-5-pyrimidinol, 4'-hydroxy-4-biphenyl carbonitrile, 3-amino-4-phenylphenol and 4, 4'-Biphenol) were respectively dissolved in N, N-dimethylformamide(DMF) detaining 4-solution samples, and the concentration was 2wt%; biphenyl derivatives were dissolved into a saturated solution of anhydrous ethanol as a solute, and the single crystals of biphenyl derivatives were obtained by slow evaporation of the ethanol solution at an ambient temperature. The experimental results show that cyclic symmetric bright-dark spatial stripes were formed after the laser beam transmitted through the 2-(4-hydroxypheny)-5-pyrimidinol, 4'-hydroxy-4-biphenyl carbonitrile and 3-amino-4-phenylphenol solutions with an asymmetric chromophore. On the other hand, the transmitted laser spot has no change in 4, 4'-Biphenol solution, no matter how the laser power density was increased. A distorted beam was observed when the 2-(4-hydroxypheny)-5-pyrimidinol, 4'-hydroxy-4-biphenyl carbonitrile, and 3-amino-4-phenylphenol single crystals were irradiated by high optical power density, while the laser beam spot experienced no change in the 4, 4'-Biphenol single crystal. The different values of the Open/Dark current were about 10 nA in biphenyl derivatives with an asymmetric chromophore. The distorted optical spot stretched along the laser polarization. The threshold value of laser power density for distorted spot was about 100 W/cm2 and 10 W/cm2 in the solutions and single crystals of biphenyl derivatives with an asymmetric chromophore. An explanation was proposed for the symmetric cyclic bright-dark spatial stripes, being that they were induced by the photorefractive effect. The photorefractive effect relies on the formation of a space-charge field through the illumination of inhomogeneous light intensity patterns. The biphenyl derivatives were found to be photorefractive materials.