Electric Field-Induced Water Condensation Visualized by Vapor-Phase Transmission Electron Microscopy
Electric Field-Induced Water Condensation Visualized by Vapor-Phase Transmission Electron Microscopy
复制标题
通过气相透射电子显微镜观察电场诱导的水凝结
DOI：
10.1021/acs.jpca.2c08187
复制
发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Woehl, Taylor J.
中科院分区：
文献类型：
--
作者：
Wang, Yuhang;Rastogi, Dewansh;Malek, Kotiba;Sun, Jiayue;Asa-Awuku, Akua;Woehl, Taylor J.
了解强电场中的纳米尺度水凝结动力学对于改进云动力学的大气建模和利用电场直接捕获空气水分的新兴技术非常重要。本研究利用气相透射电子显微镜（VPTEM）直接成像了在电场作用下固结水滴的纳米尺度凝结动力学。饱和水蒸气的VPTEM成像刺激了在一分钟的时间尺度上蒸发之前生长到约500纳米大小的无根纳米水滴的冷凝。模拟结果表明，电子束对氮化硅微流控通道窗口进行充电，产生了~ 108V/m的电场，降低了水蒸气压，影响了纳米液态水滴的快速成核。质量平衡模型表明，液滴生长符合电场诱导的冷凝，而液滴蒸发符合放射性溶解诱导的蒸发，即水转化为氢气。该模型量化了几种电子束-样品相互作用和蒸汽输运性质，表明电子束加热不显著，并表明文献值明显低估了辐射解氢产量和高估了水蒸气扩散率。本工作展示了一种研究强电场和过饱和条件下冷凝水的方法，这与对流层的汽液平衡有关。虽然这项工作确定了几种影响冷凝动力学的电子束-样品相互作用，但这些现象的量化有望在使用VPTEM成像更复杂的气液平衡现象时，从感兴趣的物理学中描述这些伪影并对其进行解释。
Understanding the nanoscale water condensation dynamics in strong electric fields is important for improving the atmospheric modeling of cloud dynamics and emerging technologies utilizing electric fields for direct air moisture capture. Here, we use vapor-phase transmission electron microscopy (VPTEM) to directly image nanoscale condensation dynamics of sessile water droplets in electric fields. VPTEM imaging of saturated water vapor stimulated condensation of sessile water nanodroplets that grew to a size of ∼500 nm before evaporating over a time scale of a minute. Simulations showed that electron beam charging of the silicon nitride microfluidic channel windows generated electric fields of ∼108V/m, which depressed the water vapor pressure and effected rapid nucleation of nanosized liquid water droplets. A mass balance model showed that droplet growth was consistent with electric field-induced condensation, while droplet evaporation was consistent with radiolysis-induced evaporationviaconversion of water to hydrogen gas. The model quantified several electron beam–sample interactions and vapor transport properties, showed that electron beam heating was insignificant, and demonstrated that literature values significantly underestimated radiolytic hydrogen production and overestimated water vapor diffusivity. This work demonstrates a method for investigating water condensation in strong electric fields and under supersaturated conditions, which is relevant to vapor–liquid equilibrium in the troposphere. While this work identifies several electron beam–sample interactions that impact condensation dynamics, quantification of these phenomena here is expected to enable delineating these artifacts from the physics of interest and accounting for them when imaging more complex vapor–liquid equilibrium phenomena with VPTEM.