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Diffusive dynamics during the high-to-low density transition in amorphous ice
  Molecular Physics seminar

Monday 03 April 2017
from 10:00 to 11:00
at FD41
Speaker : Katrin Amann-Winkel (SU, Chemical Physics)
Abstract : The amorphous forms of water play an important role in the understanding of water´s anomalous properties. Since the discovery of distinct amorphous states with different density (high- and low density amorphous ice, HDA and LDA) it has been controversially discussed whether this phenomenon of polyamorphism at high pressures is connected to the occurrence of two distinct liquid phases (HDL and LDL). Calorimetric and Dielectric measurements show evidence for a glass transition at ambient pressure in both amorphous states at two different temperatures. However, the nature of both, the experimentally observed glass transition as well as the high-to-low-density transition is still under debate. Alternatively, HDA has been discussed as mechanically collapsed crystal, unrelated to liquids. Our recent results using X-ray diffraction as well as X-ray correlation spectroscopy (XPCS) support the previous findings of HDA undergoing a glass-liquid transition at ambient pressure around 110 K and are consistent with the hypothesis of a liquid-liquid transition between HDL and LDL.

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