Periodic Reporting for period 4 - WATER (Probing the Structure and Dynamics of Water in its Various States)
Reporting period: 2020-03-01 to 2020-08-31
We need to create an overall understanding of water at different temperatures and pressures, but also how water is affected by salts and biomolecules important for life. In addition, the increased understanding of water can lead to new insights on how to purify and desalinate water in the future. This will be one of the main challenges to humanity in view of the global climate change.
Another recent discovery has to do with when water is being cold. If you chill water below 4 degrees, it starts to expand again. If you continue to cool pure water (where the rate of crystallization is low) to below 0, it continues to expand – the expansion even speeds up when it gets colder. Many more properties such as compressibility and heat capacity become increasingly strange as water is cooled. With the help of ultra-short x-ray pulses at x-ray lasers in Japan and South Korea, we have succeeded in determining that water reaches the peak of its strange behaviour at -44°C. This is the temperature when the fluctuations of the two local form of water reaches its maximum. This gives an indication that there may even exist a critical point somewhere close. The next stage is to find the location of the critical point in terms of pressure and temperature. A big challenge in the next few years.