Vapor-Liquid-Ice: Exploring Water's Phase Transitions Far from Equilibrium

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With this award, the Chemical Structure, Dynamics and Mechanisms-A (CSDM-A) and Environmental Chemical Sciences (ECS) Programs of the Division of Chemistry are funding Professor Barbara Wyslouzil at Ohio State University (OSU) to exploring how water moves between the vapor, liquid and solid states. Two phenomena that are being studied are supercooled water and supersaturated water vapor. Liquid water generally changes into ice solid water) below 32 degrees Fahrenheit (0 degrees Celsius), but sometimes it remains in liquid form well below the freezing temperature (hence the name "supercooled"). Similarly, sometimes, water can remain in vapor form well above the concentration at which it should form a liquid (condense); this point is called "supersaturated." Professor Wyslouzil and her research team are using a supersonic nozzle, infrared spectroscopy, and x-ray scattering tools to determine the limits to which water vapor can be supersaturated and liquid water supercooled, and how fast the eventual freezing and condensation occur. These questions are important in the atmosphere where the state of water affects both the ability of clouds to bounce sunlight back into space and the chemical reactions taking place within the clouds. In industry, understanding when water condenses is important to developing efficient energy extraction schemes. Professor Wyslouzil participates in OSU's Breakfast of Science Champions program and collaborates with the Steam Factory, an OSU initiative to promote interdisciplinary collaboration across Science, Technology, Engineering, Arts, and Math.To investigate phase transitions involving supercooled and supersaturated water, the Wyslouzil group has developed a transportable supersonic nozzle apparatus that is easily integrated with a broad range of analytical tools. In her lab, standard methods include static pressure measurements to characterize the flow and infrared spectroscopy to quantify the distribution of the condensable fraction among the vapor, liquid and solid states. To fully characterize the size of the aerosol droplets and their crystal structure requires spatially resolved small- and wide- angle X-ray scattering (SAXS/WAXS) experiments and these are made at national user facilities. The high transformation rates that are measured also approach those that can be directly investigated using molecular simulations. Experiments, exploring how water far from equilibrium behaves and/or transforms, are critical to advancing our understanding of the phase diagram of water, the validity of advanced water models, the anomalous behavior of this fascinating compound, and for developingaccurate models of natural and industrial processes.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.