2023 APS March Meeting
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session A03: Disorder and Fluctuations in Chemical Physics I
8:00 AM–11:00 AM,
Monday, March 6, 2023
Room: Room 126
Sponsoring
Unit:
DCP
Chair: Sapna Sarupria, University of Minnesota
Abstract: A03.00005 : Disorder and order in condensed water
9:12 AM–9:48 AM
Abstract
Presenter:
Thomas Loerting
(University of Innsbruck)
Author:
Thomas Loerting
(University of Innsbruck)
H2O as the most anomalous substance and as the key ingredient in all forms of life keeps fascinating the science community. Yet, many open questions remain in our understanding of water. The last 25 years maybe called the era of ice polymorphs, in which the crystal structures of 8 polymorphs, ice XII-ice XIX, were unraveled. All of these polymorphs feature an ordered network of oxygen atoms, but only some of them feature an ordered network of hydrogen atoms. The last 40 years may even be called the era of polyamorphism, in which three distinct amorphous ices were discovered. These can be interconverted in sharp, first-order like transitions and can be cycled back and forth just like thermodynamically stable phases in the phase diagram. Even more thrilling, amorphous ices experience reversible glass-to-liquid transitions in the range between 110 and 160 K. This makes two distinct, deeply supercooled liquids of composition H2O accessible. This recognition represents new physics per se, and it has paved the way to the discovery of novel concepts, for instance the nucleation of low-density liquid H2O in a matrix of high-density liquid H2O, with sharp phase boundaries between the two liquids. This fuels two-liquid theories of water and suggest that our understanding of the anomalies in water requires an understanding of mixing thermodynamics and dynamics. With the knowledge accumulated over the last few decades it is actually now possibe to govern the subnetworks of H and O atoms in H2O independently from each other: it is possible to control oxygen disorder, but also to govern hydrogen order and disorder in an ordered network of oxygen atoms. In my talk I will review some of this new physics and outline where I think the field may head - with the discovery of many more ice phases and with a thorough characterization of the metastable liquid-liquid phase equilibrium in a one-component system ahead of us.