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首页> 外文期刊>Applied Physics Letters >Sign reversal in the dielectric anisotropy as functions of temperature and frequency in the nematic phase of a bent-core mesogen
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Sign reversal in the dielectric anisotropy as functions of temperature and frequency in the nematic phase of a bent-core mesogen

机译：弯曲核介晶向列相中介电各向异性的符号反转随温度和频率的变化

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摘要

The sign reversal in the dielectric anisotropy (∈_‖~'-∈_⊥~') from positive to negative is observed for 4-cyanoresorcinol bisbenzoate system with temperature and frequency in the nematic phase of a bent-core system as the temperature is reduced. This cross-over in dielectric anisotropy is such that at temperatures much below the cross-over temperature, the negative anisotropy is found to be independent of frequency. The experimental observation is supported by results from optical transmittance spectroscbpy. This observation is suggested to arise from the following two sources: the presence of cybotactic clusters found by x-ray scattering in the same compound in its nematic phase and conformers that may change the bent core angle at a certain temperature as observed by nuclear magnetic resonance in a similar compound.
机译：对于4-氰基间苯二酚双苯甲酸酯系统，在温度为20℃时，在弯曲核系统的向列相中，温度和频率均发生变化，从而观察到介电各向异性（ε_‖〜'-ε_'〜'）的正负号从正向反转。减少。介电各向异性的这种交叉使得在远低于交叉温度的温度下，发现负各向异性与频率无关。光学透射光谱的结果支持了实验观察。建议从以下两个来源得出此观察结果：在同一个化合物的向列相中通过x射线散射发现的同系团簇和通过核磁共振观察到的在一定温度下可能改变弯曲核角的构象异构体在类似的化合物中。

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  • 来源
    《Applied Physics Letters》 |2010年第15期|p.152903.1-152903.3|共3页
  • 作者

    Yun Jang; Vitaly P. Panov; C. Keith; C. Tschierske; J. K. Vij;

  • 作者单位

    Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2,Ireland;

    rnDepartment of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2,Ireland;

    rnInstitute of Organic Chemistry, Martin-Luther-University Halle-Wittenberg, D-06120 Halle,Germany;

    rnInstitute of Organic Chemistry, Martin-Luther-University Halle-Wittenberg, D-06120 Halle,Germany;

    rnDepartment of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2,Ireland;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);
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  • 正文语种 eng
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