Li Xiaolai, Wang Yuliang, Zeng Binglin, Detert Marvin, Prosperetti Andrea, Zandvliet Harold J W, Lohse Detlef
Physics of Fluids, Max Planck Center Twente for Complex Fluid Dynamics and J. M. Burgers Centre for Fluid Mechanics, MESA+ Institute, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Robotics Institute, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, P. R. China.
J Phys Chem Lett. 2020 Oct 15;11(20):8631-8637. doi: 10.1021/acs.jpclett.0c02492. Epub 2020 Sep 29.
The growth of surface plasmonic microbubbles in binary water/ethanol solutions is experimentally studied. The microbubbles are generated by illuminating a gold nanoparticle array with a continuous wave laser. Plasmonic bubbles exhibit ethanol concentration-dependent behaviors. For low ethanol concentrations () of ≲67.5%, bubbles do not exist at the solid-liquid interface. For high values of ≳80%, the bubbles behave as in pure ethanol. Only in an intermediate window of 67.5% ≲ ≲ 80% do we find sessile plasmonic bubbles with a highly nontrivial temporal evolution, in which as a function of time three phases can be discerned. (1) In the first phase, the microbubbles grow, while wiggling. (2) As soon as the wiggling stops, the microbubbles enter the second phase in which they suddenly shrink, followed by (3) a steady reentrant growth phase. Our experiments reveal that the sudden shrinkage of the microbubbles in the second regime is caused by a depinning event of the three-phase contact line. We systematically vary the ethanol concentration, laser power, and laser spot size to unravel water recondensation as the underlying mechanism of the sudden bubble shrinkage in phase 2.
对二元水/乙醇溶液中表面等离子体微泡的生长进行了实验研究。通过用连续波激光照射金纳米颗粒阵列来产生微泡。等离子体气泡表现出与乙醇浓度相关的行为。对于乙醇浓度（）≲67.5%的低浓度情况，在固液界面不存在气泡。对于≳80%的高值，气泡的行为与在纯乙醇中一样。只有在67.5%≲≲80%的中间窗口中，我们才发现具有高度复杂时间演化的固定等离子体气泡，其中随着时间的推移可以辨别出三个阶段。（1）在第一阶段，微泡生长，同时摆动。（2）一旦摆动停止，微泡进入第二阶段，在该阶段它们突然收缩，随后是（3）稳定的再进入生长阶段。我们的实验表明，第二阶段微泡的突然收缩是由三相接触线的脱钉事件引起的。我们系统地改变乙醇浓度、激光功率和激光光斑尺寸，以揭示水再凝结是第二阶段气泡突然收缩的潜在机制。
