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"The Origin of the Anomalous Properties of Water"
Thursday, 07. March 2019
Video-Recording for any system with MP4-support
- Video.mp4 (ca.418 Mb)
15:15 – 16:15
Water has remarkable physical properties that differ from almost all other liquids.
Deviation of these properties from a simple liquid exists already in the ambient
temperature regime and then becomes strongly enhanced upon supercooling.
In particular the finding that the thermodynamic response and correlation functions
appear to diverge towards a singular temperature estimated by power-law fits of
about 228 K has led to several hypotheses about the origin of waters anomalous
properties. One hypothesis to explain the apparent divergence is that there exists
a liquid-liquid transition with a liquid-liquid critical point at rather high positive
pressures. In this scenario the Widom line, defined as the locus of correlation length
maxima in the P-T plane, emanates from the critical point as a continuation of the
liquid-liquid transition line into the one-phase region and the divergence in the
response functions is towards this line. The challenge is that the temperature Ts lies
below the homogeneous ice nucleation temperature 232 K, a region of the phase
diagram that has been denoted as “no man’s land”, since ice crystallization occurs
on much faster time scale compared to the experimentally accessible time scale in a
typical laboratory setting.
Here I will present how x-rays from x-ray lasers and synchrotron radiation sources
can be used to probe the liquid in the deep supercooled water regime inside no-man’s
land. In particular I will discuss if a liquid-liquid transition, Widom line and a critical
point exists in deep supercooled water causing fluctuations all the way up to ambient
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