Scientists at the Swiss Federal Institute of Technology Lausanne (EPFL) have made a groundbreaking discovery in the study of water. They have found a way to explore the properties of water in a temperature range known as “no man’s land,” where water crystallizes rapidly, making it difficult to analyze its anomalous nature. Water is a fundamental compound on Earth, playing crucial roles in various aspects of our planet. However, it also exhibits peculiar behaviors that have intrigued scientists for years.
Understanding the anomalies of water has been challenging due to the inability to study it between temperatures of 160 K and 232 K (-113 °C to -41 °C), where it freezes quickly. The temperature range, known as “no man’s land,” has hindered scientists from experimental verification of various theories explaining water’s unusual properties.
To comprehend why water behaves strangely, researchers often cool it significantly below its freezing point, resulting in a supercooled state with distinct characteristics. For instance, under specific conditions, supercooled water can remain in a liquid state but freeze instantly when disturbed or exposed to certain substances. However, even with cooling tricks to delay crystallization, the process remains too rapid within “no man’s land.”
Professor Ulrich Lorenz from EPFL’s School of Basic Sciences expressed the challenge, stating that studying water across “no man’s land” has eluded scientists for decades. However, Lorenz and his team have now achieved a breakthrough. They have devised a method to rapidly prepare deeply supercooled water at a precisely defined temperature and examine it using electron diffraction before crystallization occurs.
The scientists designed a specialized time-resolved electron microscope for their experiments. They cooled a layer of graphene to 101 K and applied a thin film of amorphous ice, a disordered state of ice molecules unlike the typical crystalline ice. By locally melting the film with a microsecond laser pulse, they obtained water in “no man’s land” and captured a diffraction pattern using an intense, high-brightness electron pulse.
The research team observed that as water is cooled from room temperature to cryogenic temperatures, its structure undergoes a smooth transition. Just below 200 K (around -73 °C), the water’s structure resembles that of amorphous ice, providing new insights into its behavior.
Lorenz explains that the smooth evolution of water’s structure allows them to narrow down the possible explanations for its anomalous properties. The team’s findings and the developed methodology bring them closer to unraveling the mysteries of water. Lorenz emphasizes the fascination surrounding this seemingly simple yet ubiquitous liquid that still holds secrets yet to be fully understood.
The research, published in the journal Nature Communications, marks a significant step forward in studying water in “no man’s land” and offers new avenues for exploring its unique characteristics.