脆性氢键液体结构不均匀性的实验研究
Experimental Indication of Structural Heterogeneities in Fragile Hydrogen-bonded Liquids
摘要：
我们提出了第一个实验表征分子易碎的玻璃形成的一个“prepeak，出现显着低于主峰的静态结构因子。这个预峰的温度和密度的依赖关系进行了研究，通过弹性中子散射实验在高压下（高达300 MPa），在间甲苯胺和间氟苯胺。预峰强度随温度的降低而增加，但随压力的增加而保持不变，而其位置和宽度大致保持不变。这些特征与观察到的网络玻璃的“第一尖锐衍射峰”相反。借助蒙特卡罗模拟分析了这一现象的根源。我们关联的prepeak氢键诱导的异质性（或集群），其有限的大小的结果从苯环之间的排斥效应，防止氢键网络的扩展。最后被认为是接近玻璃化转变的液体的动力学的影响。
英文摘要：
We present the first experimental characterization in molecular fragile glassformers of a 'prepeak that appears significantly below the main peak of the static structure factor. The temperature and density dependences of this prepeak are studied via elastic neutron scattering experiments under high pressure (up to 300 MPa) in m-toluidine and m-fluoroaniline. The prepeak intensity increases with decreasing temperature, but it remains constant with increasing pressure while its position and width stay roughly the same. These features are opposite to those observed for the 'first sharp diffraction peak' of network glasses. The origin of the phenomenon is analyzed with the help of Monte Carlo simulations. We associate the prepeak to hydrogen-bond-induced heterogeneities (or clusters) whose limited size results from exclusion effect between benzene rings that prevents the extension of a hydrogen-bond network. Implications for the dynamics of the liquid close to the glass transition are finally considered.
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