Petersen C, Tielrooij K-J, Bakker H J
FOM Institute for Atomic and Molecular Physics, Science Park 113, 1098 XG Amsterdam, The Netherlands.
J Chem Phys. 2009 Jun 7;130(21):214511. doi: 10.1063/1.3142861.
We study the temperature dependence of the orientational mobility of water molecules solvating hydrophobic molecular groups with femtosecond midinfrared spectroscopy. We observe that these dynamics show a strong temperature dependence. At temperatures <30 degrees C the solvating water molecules show a reorientation time >10 ps, which is more than four times slower than in bulk water. With increasing temperature, the reorientation of the solvating molecules strongly accelerates and becomes much more equal to the reorientation rate of the molecules in the bulk liquid. These observations indicate that water molecules form relatively rigid solvation structures around hydrophobic molecular groups that melt at elevated temperatures.
我们利用飞秒中红外光谱研究了溶剂化疏水分子基团的水分子取向迁移率与温度的关系。我们观察到这些动力学表现出强烈的温度依赖性。在温度低于30摄氏度时，溶剂化水分子的重新取向时间大于10皮秒，这比本体水中的速度慢四倍多。随着温度升高，溶剂化分子的重新取向强烈加速，并且变得与本体液体中分子的重新取向速率更加接近。这些观察结果表明，水分子在疏水分子基团周围形成相对刚性的溶剂化结构，这些结构在升高的温度下会熔化。
