Dipartimento di Fisica E. Amaldi, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy.
J Phys Chem B. 2009 Dec 17;113(50):16169-77. doi: 10.1021/jp9062109.
We present a protocol for simultaneous structural characterization of a confined fluid and the confining substrate, along with the extraction of site-site pair correlation functions of the liquid of interest. This is based on neutron diffraction experiments, exploiting where feasible the isotopic substitution technique, analyzed through numerical coarse graining calculations and atomistic simulations. All of the subtleties of the experimental procedure, the needed ancillary measurements, and the recipe for tailoring the numerical codes to the real experiment and sample are described in the case of water confined in MCM41-S-15. In particular the excluded volume effects and the relevance of liquid-substrate cross-correlation terms in the neutron cross section are quantitatively discussed. The results obtained for the microscopic structure of water evidence a non-homogeneous distribution of molecules within the pore, with the presence of water-substrate hydrogen bonds, and a strong distortion of the water-water radial distribution functions with respect to those of bulk water extending at least up to three hydration layers.
我们提出了一种同时对受限流体和约束基底进行结构表征的方案，并提取了感兴趣液体的位点位相互关联函数。这是基于中子衍射实验，在可行的情况下利用同位素取代技术，通过数值粗粒化计算和原子模拟进行分析。在 MCM41-S-15 中受限水的情况下，详细描述了实验过程中的所有细微差别、所需的辅助测量以及为适应实际实验和样品定制数值代码的方法。特别是定量讨论了中子截面中排除体积效应和液体-基底交叉相关项的相关性。对水的微观结构的研究结果表明，分子在孔内的分布不均匀，存在水分子-基底氢键，并且水-水径向分布函数相对于至少三个水合层的体相水发生强烈扭曲。
