Generation of Supra-molecular Cluster Structure and its Binding Condition

通过对液滴中团簇的质谱分析和完整溶液的X射线衍射测量，研究了x_E(乙醇摩尔分数)&lt；大于或等于-gt；0.2的乙醇-水二元溶液中团簇的结构。在小于或等于-gt；x_E&lt；0.8的混合物中，乙醇分子水合物(5&lt；m&lt；15)的平均水分子数(N^a)用水的摩尔分数(X_W)的函数表示：Na^a={(m/4.2)-1}^2(x_w 0.85)，这表明乙醇聚合物水合物的基本结构在该区域是不变的。N^a的拐点出现在x_3&lt；近似等于&gt；0.2处。由X射线测量得到的径向分布函数(RDF)表明，随着x_E的增加，线性氢键在2.8*处减小，而在-gt；x_E&lt；小于或等于&gt；1.0时，最强的氢键保持在4.8*处。在质谱图成分分析和RDF浓度依赖关系的基础上，我们提出了最有可能的乙醇-水二元团簇形成模型，该模型形成于小于或等于-gt；x_E&lt；小于或等于&gt；0.8的区域。

The structure of clusters in ethanol-water binary solutions at x_E (ethanol mole fraction) <greater than or equal>0.2 is investigated by the mass spectrometric analysis of the clusters isolated from liquid droplets and X-ray diffraction measurements of intact solution. Average numbers of water molecules (N^a) of the ethanol m-mer hydrates (5<m<15) in the mixtures at 0.2<less than or equal>x_E<less than or equal>0.8 are found to be expressed by a function of water mole fraction (x_w) : Na^a={(m/4.2) -1} ^2 (x_w+0.85), suggesting that the fundamental structure of the ethanol polymer-hydrates is invariable in thie region. An inflection point of N^a was found at x_3<approximately equal>0.2. The radial distribution functions (RDFs) fromthe X-ray measurements demonstrated a decrease of linear hydrogen bonds at 2.8 * with increasing x_E, while keeping the strongest peak at 4.8 * in 0.4<less than or equal>x_E<less than or equal>1.0. On the basis of the composition analysis of the mass spectra and the concentration dependence of RDFs, we propose the most likely model of ethanol-water binary clusters formed in the region 0.2<less than or equal>x_E<less than or equal>0.8.