“Supercooled” Water Transforms from Liquid to Liquid
When water is cooled to a very low temperature, well below its normal freezing temperature, it transforms into a new form of liquid, what Feng “Seymour” Wang in the department of chemistry and biochemistry calls “supercooled” water. Wang and his research team, which included research assistants Yaping Li and Jicun Li, found that when water is cooled to a very low temperature, a “liquid-liquid” phase transition occurs at 207 Kelvins, or 87 degrees below zero on the Fahrenheit scale. “On a microsecond time scale, the water did not actually form ice but it transformed into a new form of liquid,” Wang said. “The study provides strong supporting evidence of the liquid-liquid phase transition and predicted a temperature of minimum density if water can be cooled well below its normal freezing temperature. Our study shows water will expand at a very low temperature even without forming ice.” The liquid-liquid transition in supercooled water can be used to explain many anomalous behaviors of water. For example, the properties of supercooled water are important for understanding the processes of cryoprotection, which is the preservation of tissue or cells by liquid nitrogen so they can be thawed without damage.