Caporaletti Federico, Bittermann Marius R, Bonn Daniel, Woutersen Sander
Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, 1098XH Amsterdam, The Netherlands.
Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, 1098XH Amsterdam, The Netherlands.
J Chem Phys. 2022 May 28;156(20):201101. doi: 10.1063/5.0092248.
Viscosity is a key property of liquids, but it is difficult to measure in short-lived, metastable samples due to the long measuring times required by conventional rheology. Here, we show how this problem can be solved by using fluorescent molecular rotors. The excited-state fluorescence decay rate of these molecules is sensitive to the viscosity of their local environment, and by combining pulsed laser excitation with time-resolved fluorescence detection, we can measure viscosities with a time resolution of a few ns. We demonstrate this by measuring in real time the viscosity change in glycerol induced by a nanosecond temperature jump. This new approach makes it possible to measure the viscosity of extremely short-lived states of matter.
粘度是液体的一个关键特性，但由于传统流变学所需的测量时间较长，因此很难对短寿命、亚稳态样品进行测量。在此，我们展示了如何通过使用荧光分子转子来解决这个问题。这些分子的激发态荧光衰减率对其局部环境的粘度敏感，通过将脉冲激光激发与时间分辨荧光检测相结合，我们可以以几纳秒的时间分辨率测量粘度。我们通过实时测量由纳秒级温度跃升引起的甘油粘度变化来证明这一点。这种新方法使得测量物质极短寿命状态的粘度成为可能。
