Abstract
In this paper we discuss apparent contradictions in the literature between dynamical results on supercooled confined water obtained by different experimental methods. The reason for the lack of a clear glass transition of confined water is also discussed. Dielectric relaxation data and results from differential scanning calorimetry measurements provide a consistent picture, but it is still unclear why the glass transition related structural (α) relaxation disappears before the normal time-scale of a calorimetric glass transition (i.e. about 100 s) is reached. From recent results on amorphous bulk ice we propose that this anomalous phenomenon may not be an effect of confinement, but an intrinsic property of water when it transforms to a crystal-like glassy state, probably around 225 K. Thus, the results from the studies of confined water in the so-called no man's land (the temperature range 150-235 K) where bulk water rapidly crystallizes may be of more relevance for supercooled and glassy bulk water than previously thought. Furthermore, the structural difference between glassy water (or amorphous ice) and crystalline ice is likely to be rather small, due to the large degree of disorder in crystalline ice.
Highlights
IntroductionJan Swenson earned his PhD in Physics at Chalmers University of Technology, Sweden, in 1996
We all know that we need water for our survival.[1]
The dynamics of confined water in the deeply supercooled regime and its possible implications for bulk water have been discussed in this work
Summary
Jan Swenson earned his PhD in Physics at Chalmers University of Technology, Sweden, in 1996. The advantage with QENS from this perspective is that it is possible to distinguish between localized, rotational and long-range translational motions by measuring how the relaxation time depends on the momentum transfer (Q) of the scattering event.[21,22] In the case of hydrogen-rich materials, such as H2O, the total scattering is strongly dominated by the large incoherent scattering of hydrogen, and it measures the self-motions of these atoms.[21,22] there are different types of NMR measurements, where 2H stimulated echo (STE) experiments are useful to provide information about the overall amplitude and jump angles of a reorientational motion, which can be used to distinguish between a- and b-relaxations.[23] it is clear from the literature that it is far from trivial to distinguish between different types of motions and to understand their physical nature. Perspective temperature of 136 K (for hyperquenched water and low-density amorphous ice),[41] which suggest that bulk water in the main temperature range of no man’s land behaves very to confined water below a temperature of about 180 K.36,38,39,42–44 an interesting question arises of whether the properties of deeply supercooled and glassy confined water are of more relevance for bulk water than previously thought
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