Scientists have verified that water has a critical point for liquid-liquid phase change and can be transformed between the two liquid phases.

Using the laser SACLA of the Japanese X-ray free electron laser facility, the team at the Institute of Science and Chemistry in Japan successfully captured the structure of the over-cold water (H2O), verified the critical point of liquid-liquid phase change in water, and was able to transition between the two liquid phases.
life can not be separated from water, but people's understanding of water is not perfect.
the thermal characteristics of water in the temperature reduction, thermal capacity, isometric compression rate and other thermodynamic characteristics of the opposite state with other liquids, which led to a long-term debate on the thermodynamic characteristics of water, there are various hypotheses.
one hypothesis is that liquid water has two phases with different densities and swings between them.
but the water is unstable and freezes quickly when the temperature drops to near 0C (over-cold), so it has been extremely difficult to verify this hypothesis so far.
the joint team used SACLA to irradiate water droplets in a cold state and analyzed the structure of water.
SACLA pulse width is very short in femtoseconds and can measure changes over time before the cooling water freezes.
the team obtained data on water at various temperatures, obtained the structure of water by analyzing X-rays scattered by water droplets, and investigated the increase in the isometric compression rate of water when cooled.
found that the isometric compression rate is the maximum at -44 degrees C, below this temperature when the reversal occurs, the hydrogen atom (H) in the water is replaced with heavy water (D2O) of heavy hydrogen atom (D), and the isometric compression temperature is -40 degrees C.
these findings suggest that there is a critical point for liquid-liquid phase change in water, which affects the quantum effect of the nucleus.
the results of the study explain the origin of the inherent thermodynamic morphology of water, and the relevant papers have been published in the online edition of the journal Science.
Source: Science Daily.