On the mechanism of the Hofmeister effect
On the mechanism of the Hofmeister effect
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DOI：
10.1021/ja047715c
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发表时间：
2004-09-01
影响因子：
15
通讯作者：
Cremer, PS
中科院分区：
文献类型：
--
作者：
Gurau, MC;Lim, SM;Cremer, PS
振动和频光谱被用来探测脂肪胺单分子膜上的各种电解质溶液。光谱揭示了单层有序和水结构的离子特定变化，前者遵循霍夫迈斯特系列。单独测量的表面电位作为离子的函数跟踪密切的烷基链结构的变化，但不太密切的水结构的变化。单层有序的破坏可以归因于离子的相对能力，以渗透过去的单层的头基的亲水性表面，并进入更疏水的部分的薄膜。在地表水结构中观察到的相应趋势显示出与霍夫迈斯特系列的显著偏差，从而得出这样的结论：通常被认为是霍夫迈斯特效应起源的地表水结构的变化可能并不是最重要的。另一方面，色散力几乎肯定在霍夫迈斯特级数的阶数中起着重要作用。
Vibrational sum frequency spectroscopy was used to probe fatty amine monolayers spread on various electrolyte solutions. The spectra revealed ion specific changes in both monolayer ordering and water structure with the former following the Hofmeister series. Separate measurements of the surface potential as a function of ion tracked closely to changes in alkyl chain structure, but less closely to changes in water structure. The disruption of the monolayer ordering could be ascribed to the relative ability of the ions to penetrate past the hydrophilic surface of the monolayer's headgroups and into the more hydrophobic portion of the thin film. The corresponding trends observed in the surface water structure showed significant deviations from the Hofmeister series, leading to the conclusion that the changes in surface water structure, often credited with being the origin of Hofmeister effects, are probably not of primary importance. On the other hand, dispersion forces almost certainly play a large role in the order of the Hofmeister series.