Strong Electric Field Observed at the Interface of Aqueous Microdroplets
Strong Electric Field Observed at the Interface of Aqueous Microdroplets
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DOI：
10.1021/acs.jpclett.0c02061
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发表时间：
2020-09-03
影响因子：
5.7
通讯作者：
Min, Wei
中科院分区：
文献类型：
--
作者：
Xiong, Hanqing;Lee, Jae Kyoo;Min, Wei
在水微液滴中的化学反应通常表现出在整体溶液中没有观察到的异常的动力学和热力学性质。虽然在水界面上存在电场，但由于缺乏适当的测量工具，没有直接测量水微滴中的电场。在这里，我们使用新发展的受激拉曼激发荧光显微镜来测量微滴水-油界面的电场。由含腈荧光探针的振动斯塔克效应确定，电场强度约为10(7)V/cm。这个强大的电场使探头偶极子相对于界面对准。电场的形成可能是由于负离子在微滴的水-油界面上的吸附而导致的电荷分离。我们认为，这种强大的电场可能在一定程度上解释了微滴中报道的化学反应的独特性质。
Chemical reactions in aqueous microdroplets often exhibit unusual kinetic and thermodynamic properties not observed in bulk solution. While an electric field has been implicated at the water interface, there has been no direct measurement in aqueous microdroplets, largely due to the lack of proper measurement tools. Herein, we employ newly developed stimulated Raman excited fluorescence microscopy to measure the electric field at the water-oil interface of microdroplets. As determined by the vibrational Stark effect of a nitrile-bearing fluorescent probe, the strength of the electric field is found to be on the order of 10(7) V/cm. This strong electric field aligns probe dipoles with respect to the interface. The formation of the electric field likely arises from charge separation caused by the adsorption of negative ions at the water-oil interface of microdroplets. We suggest that this strong electric field might account in part for the unique properties of chemical reactions reported in microdroplets.