Dokter Adriaan M, Woutersen Sander, Bakker Huib J
FOM-Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ, Amsterdam, The Netherlands.
Proc Natl Acad Sci U S A. 2006 Oct 17;103(42):15355-8. doi: 10.1073/pnas.0603239103. Epub 2006 Oct 6.
The effect of confinement on the dynamical properties of liquid water was studied by mid-infrared ultrafast pump-probe spectroscopy on HDO:D2O in reverse micelles. By preparing water-containing reverse micelles of different well defined sizes, we varied the degree of geometric confinement in water nanodroplets with radii ranging from 0.2 to 4.5 nm. We find that water molecules located near the interface confining the droplet exhibit slower vibrational energy relaxation and have a different spectral absorption than those located in the droplet core. As a result, we can measure the orientational dynamics of these different types of water with high selectivity. We observe that the water molecules in the core show similar orientational dynamics as bulk water and that the water layer solvating the interface is highly immobile.
通过对反胶束中HDO:D2O进行中红外超快泵浦-探测光谱研究，探讨了受限环境对液态水动力学性质的影响。通过制备不同明确尺寸的含水反胶束，我们改变了半径在0.2至4.5纳米范围内的水纳米滴中的几何受限程度。我们发现，位于限制液滴的界面附近的水分子表现出较慢的振动能量弛豫，并且与位于液滴核心的水分子具有不同的光谱吸收。因此，我们能够以高选择性测量这些不同类型水的取向动力学。我们观察到，核心中的水分子表现出与 bulk 水相似的取向动力学，并且溶剂化界面的水层高度不流动。
