Dependence of Homoimmiscible Water Dynamics on Overpressure at the Interface between Water and the Basal Plane of Single-Crystal Ice I_h

Interfacial phenomena between ice and water play a key role in ice formation. Previous studies have strongly focused on the microscopic details of the interfacial phenomena at the molecular level because insights from molecular dynamics (MD) simulations have advanced more than experimental insights. We recently discovered “homoimmiscible water”, which is macroscopically separated from bulk water, at the interface between water and ice grown by decompression or melted by compression. This discovery has the potential to open a new avenue of knowledge based on macroscopic viewpoints. However, systematic observations are still underway. Here, we investigated the dependence of the dynamics of the homoimmiscible water on overpressure by in situ interferometric observations on the basal plane of a single crystal of ice. Our observations suggested two types of extinction dynamics: (i) one-step shrinkage of a thin layer of homoimmiscible water; and (ii) two-step successive shrinkage of bulky droplet-like and layered homoimmiscible water. An interferometric study suggested that the thickness of the bulky layer is proportional to the overpressure. These results provide insights not only into ice formation but also into the unknown properties of water.