Department of Chemistry, University of Bergen, Realfagbygget, Allégaten 41, N-5007 Bergen, Norway.
Langmuir. 2013 Sep 3;29(35):11055-61. doi: 10.1021/la401972g. Epub 2013 Aug 22.
Thin films of water between glass plates were investigated in this study with regard to water structure and dynamics in the temperature range of 278-313 K. We further investigated how addition of 1-butanol (0.05 and 0.5 M) affects the range and properties of the surface-induced water structures. From the observation of two (1)H nuclear magnetic resonance (NMR) water resonances and two relaxation components, it was found that the interfacial water exists in a two-state mixture in dynamic equilibrium, with the respective structures interpreted as being high-density water (HDW) and low-density water (LDW). In the absence of 1-butanol, the LDW state is more pronounced, with a further shift in equilibrium toward the LDW state with an increase in temperature. However, in water film samples containing 1-butanol, the HDW state dominates at low temperatures while the LDW state becomes more visible at higher temperatures. Furthermore, the addition of 1-butanol significantly increased the extent of the surface-induced water structures. NMR relaxation shows that the dynamics of water in the HDW state is significantly affected by the presence of 1-butanol and further indicates that the distribution of values for the enthalpy of activation associated with translational motion of water molecules in the HDW state is narrower in the 0.05 M 1-butanol sample than in the 0.5 M 1-butanol sample.
本研究考察了玻璃板间的水薄膜，涉及 278-313 K 温度范围内的水结构和动力学。我们进一步研究了添加 1-丁醇（0.05 和 0.5 M）如何影响表面诱导水结构的范围和性质。通过观察两个（1）H 核磁共振（NMR）水共振和两个弛豫分量，发现界面水以两种状态的混合物存在于动态平衡中，相应的结构解释为高密度水（HDW）和低密度水（LDW）。在没有 1-丁醇的情况下，LDW 状态更为明显，随着温度的升高，平衡进一步向 LDW 状态移动。然而，在含有 1-丁醇的水膜样品中，HDW 状态在低温下占主导地位，而 LDW 状态在较高温度下变得更加明显。此外，添加 1-丁醇显著增加了表面诱导水结构的范围。NMR 弛豫表明，HDW 状态下水的动力学受到 1-丁醇的存在显著影响，并进一步表明与 HDW 状态下水分子平移运动相关的活化焓值分布的数值在 0.05 M 1-丁醇样品中比在 0.5 M 1-丁醇样品中更窄。
