The manipulation of liquids at nanoscale dimensions is a central goal of the emergent nanofluidics field. Such endeavors extend to nanodroplets, which are ubiquitous objects involved in many technological applications. Here, we employ time-resolved electron microscopy to elucidate the formation of so-called jumping nanodroplets on a graphene surface. We flash-melt a thin gold nanostructure with a laser pulse and directly observe how the resulting nanodroplet contracts into a sphere and jumps off its substrate, a process that occurs in just a few nanoseconds. Our study provides the first experimental characterization of these morphological dynamics through real-time observation and reveals new aspects of the phenomenon. We observe that friction alters the trajectories of individual droplets. Surprisingly, this leads some droplets to adopt dumbbell-shaped geometries after they jump, suggesting that they spin with considerable angular momentum. Our experiments open up new avenues for studying and controlling the fast morphological dynamics of nanodroplets through their interaction with structured surfaces.

中文翻译：

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实时观察跳跃和旋转的纳米液滴。


纳米级液体的操纵是新兴纳米流体领域的中心目标。这些努力延伸到纳米液滴，纳米液滴是许多技术应用中普遍存在的物体。在这里，我们采用时间分辨电子显微镜来阐明石墨烯表面上所谓的跳跃纳米液滴的形成。我们用激光脉冲闪熔薄金纳米结构，并直接观察所得纳米液滴如何收缩成球体并从其基底上跳出，这一过程仅在几纳秒内发生。我们的研究通过实时观察首次对这些形态动力学进行了实验表征，并揭示了该现象的新方面。我们观察到摩擦改变了单个液滴的轨迹。令人惊讶的是，这导致一些液滴在跳跃后呈现出哑铃形的几何形状，这表明它们以相当大的角动量旋转。我们的实验开辟了通过纳米液滴与结构化表面相互作用来研究和控制纳米液滴的快速形态动力学的新途径。