ERI: Nanoscale and in-situ measurement of evaporating liquid thin film thickness

超快蒸发现象最近被报道，它可以应用于设计高效的传热装置，如蒸发器、冷却器和冷凝器。高效热能系统可以通过减少能源消耗在气候危机中发挥关键作用。然而，由于纳米尺度液膜蒸发动力学测量技术的限制，超快蒸发超越理论极限的基本机理仍未确定。采用基于纳米光子学和光干涉的高灵敏度成像技术来研究蒸发过程中液膜的浓度、温度和厚度，但不能研究蒸发过程中液膜的厚度。因此，该项目的原理是通过测量和分析来深入了解超快蒸发的潜在机制。该项目还将包括重要的教育活动，如本科/研究生研究项目、课程开发和面向当地高中生的推广项目。本项目的目标是在纳米尺度上实时研究蒸发液体薄膜，为过渡区在最近报道的超快蒸发中的作用提供实验证据，并了解其潜在的物理特性。在亲水性表面上有超快蒸发的报道，但由于现有技术难以测量，其作用机理尚不清楚。本项目将通过实验和分析实现这一目标：(i)在石墨烯/金薄膜超表面上使用亚纳米驱动器进行纳米级薄膜校准，（ii）在平面和二维纳米通道上不同表面润湿性和热流密度下的纳米级薄膜动力学，以及（iii）开发表面等离子体共振成像和反射干涉条纹同步技术，用于从太阳纳米级到数百微米级的广泛薄膜动力学。利用超表面技术，利用表面等离子体共振成像技术检测亚纳米分辨率的液膜厚度变化。还将验证反射干涉条纹技术，以补充表面等离子体共振的结果。绝热和扩散膜理论将与实验和数值模拟（如射线追踪和建模）进行比较。该项目有望通过创新的光学表征及其物理理解，在蒸发、沸腾、冷凝和表面润湿等近地表现象方面取得突破。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Ultrafast evaporation phenomena have been recently reported, which can be applied to design high-efficient heat transfer devices such as evaporators, coolers, and condensers. High-efficient thermal energy systems can play a critical role in the climate crisis by reducing energy consumption. However, the fundamental mechanism for ultrafast evaporation beyond the theoretical limit is still being determined because of the limitation of measurement technology for the nanoscale liquid film dynamics during evaporation. The highly sensitive imaging technique based on nanophotonics and optical interference has been introduced to explore the concentration, temperature, and thickness, but not nanoscale liquid film thickness in evaporation. Therefore, the principle of this project is to provide a deep understanding of the underlying mechanism of ultrafast evaporation by measurement and analysis. The project will also include significant educational activities such as undergraduate/graduate research programs, course development, and outreach program for local high school students.The goal of this project is to study the evaporating liquid thin film in nanoscale and real-time to provide experimental evidence for the role of transition region in the recently reported ultrafast evaporation and understand its underlying physics. Ultrafast evaporation is reported on hydrophilic surfaces, but its working mechanism is not clear because of measurement difficulty with existing techniques. This project will achieve this goal by experiment and analysis: (i) Nanoscale thin film calibration with a sub-nanometer actuator on graphene/Au film metasurface, (ii) Nanoscale thin film dynamics under varying surface wettability and heat flux on flat and two-dimensional nanochannel, and (iii) Development of simultaneous technique of surface plasmon resonance imaging and reflection interference fringe for a broad range of film dynamics from sun-nanometers to hundreds of micron scales. Surface plasmon resonance imaging will be used to detect liquid film thickness variation in sub-nanometer resolution with the metasurface technique. The reflection interference fringe technique will also be verified to complement the result by surface plasmon resonance. Adiabatic and diffusive film theory will be compared with experiments and numerical simulation such as ray tracing and modeling. This project is expected to provide a breakthrough in near-surface phenomena, including evaporation, boiling, condensation, and surface wetting, through innovative optical characterization and its physical understanding.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.