Department of Chemistry, Columbia University, New York, NY 10027, USA.
Chem Soc Rev. 2014 Feb 21;43(4):977-89. doi: 10.1039/c3cs60186b.
Much of the interesting behavior that has been observed in supercooled liquids appears to be related to dynamic heterogeneity, the presence of distinct dynamic environments - with no apparent underlying structural basis - in these systems. To most directly interrogate these environments, proposed to span regions just a few nanometers across, molecular length scale probes are required. Single molecule fluorescent microscopy was introduced to the field a decade ago and has provided strong evidence of dynamic heterogeneity in supercooled systems. However, only more recently has the full set of challenges associated with interpreting results of these experiments been described. With a fuller understanding of these challenges in hand, single molecule measurements can be employed to provide a more precise picture of dynamic heterogeneity in supercooled liquids and other complex systems. In this tutorial review, experimental and data analysis details are presented for the most commonly employed single molecule approach to studying supercooled liquids, the measurement of rotational dynamics of single molecule probes. Guidance is provided in experimental set-up and probe selection, with a focus on choices that affect data interpretation and probe sensitivity to dynamic heterogeneity.
在过冷液体中观察到的许多有趣行为似乎都与动态异质性有关，即在这些体系中存在明显不同的动态环境——没有明显的潜在结构基础。为了最直接地探究这些环境，需要使用分子长度尺度的探针。单分子荧光显微镜在十年前被引入该领域，为过冷系统中的动态异质性提供了有力证据。然而，直到最近才描述了与解释这些实验结果相关的所有挑战。随着对手头这些挑战的更全面理解，可以采用单分子测量来更精确地描绘过冷液体和其他复杂系统中的动态异质性。在本教程综述中，介绍了最常用的单分子方法研究过冷液体的实验和数据分析细节，即单分子探针的旋转动力学测量。提供了实验设置和探针选择方面的指导，重点是影响数据解释和探针对动态异质性的敏感性的选择。
