Observing Ice Nucleation From Water Microdroplet Freezing Below “Homogenous Nucleation Temperature Limit”

Water is one of the most fascinating and arguably the most important substance in our life, environment, and industry, due to many anomalous physical properties, and many phases of solid it forms. Although there have been many experiments performed to understand water and its phase transition, there is still a region below “homogenous nucleation temperature limit”, ~232K, where water is not well understood due to rapid crystallization complicating experimental studies. Understanding phase transition within this region is also important to predict cloud properties and phases of water in the interstellar space. To date, the limited number of experiments performed limits our knowledge of water freezing within this region. A recent development in an ultrafast and ultrabright X-ray Free Electron Laser at the Linac Coherent Light Source (LCLS) enable researchers to probe matter in high resolution by taking snapshots using femtoseconds long X-ray pulses. Here we will present our ongoing effort to understand phase transition below the “homogenous nucleation temperature limit” from our recent wide angle X-ray scattering experiment using a specialized setup to take advantage of the X-ray laser at LCLS.