CC BY
23LD-O-5
LASER DIAGNOSTICS AND SPECTROSCOPY
Quantum physics of nano-confined water
VUskov1, M. A. Belyanchikov1, M. Savinov2, V. A. Abalmasov3, E. S. Zhukova1,
V. G. Thomas4 , B.Gorshunov1
1- Moscow Institute of Physics and Technology (National Research University), Moscow, Russia 2- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic 3- Institute of Automation and Electrometry SB RAS, Novosibirsk, Russia 4-Institute of Geology and Mineralogy, Russian Academy of Sciences, Novosibirsk, Russia; Novosibirsk State
University, Novosibirsk, Russia vladimir-ouskov@yandex.ru
ALT'22
Since separate water molecules possess large electric dipole moment (1.85 Debye) their mutual ferroelectric/anti-ferroelectric ordering mediated by dipole-dipole coupling can be expected. In liquid water or water ice such ordering does not happen due to intermolecular hydrogen bonds that overwhelm dipolar interaction. The existence of a so-called "water ferroelectricity" has been the subject of debate for decades. It is believed that water ferroelectricity can play crucial role in a variety of phenomena and areas of natural sciences, e.g., geology, mineralogy, meteorology, soil chemistry, biology, pharmaceutics, food industry and materials science, as well as in the living organisms (water in cells and membrane channels, and proteins hydration shells) and even in the universe (formation of planets or of prebiotic compounds). It turned out, however, that a detailed study of the phenomenon is hampered by the difficulties of its implementation in laboratory conditions. Since years, corresponding experimental results remained controversial, so that the community had to be "satisfied" with theoretical considerations and computer simulations of possible ordering of H2O molecular dipoles.
We found an ideal workbench for studying single-particle and collective effects, including ferroelectricity, in ensembles of dipole-dipole coupled water molecules. It is provided by hydrated dielectric crystals of the beryl family. The crystals contain just separate H2O molecules isolated within nanosized voids formed by the lattice ions. Being only weakly linked to the ions and separated by 5-10 A, the water molecules do not experience H-bonding (interaction length 1-2 A); nevertheless, they interact via longer-range dipole-dipole coupling (interaction length 10-100 A). This kind of network is of broad interest and fundamental importance providing the opportunity to study not only the famous "water ferroelectricity", but also diverse quantum physics of electric-dipolar systems whose properties should be qualitatively different from those occurring in well studied systems with magnetic moments.
We have discovered quantum paraelectricity [1,2] and fingerprints of quantum critical behavior [3], below 20-30 K, of a network of H2O molecules hosted by the hexagonal matrix of beryl crystal lattice. Below T=0.5 K, we discover an ordered state of water molecules, with the phase transition of yet unknown nature. In orthorhombic matrix of a relative crystal, cordierite, we have observed an order-disorder type ferroelectric phase transition [4], at around 3 K, into a complex ferroelectrically/antiferroelectrically ordered state of polar H2O molecules. In addition to collective phenomena, we studied single-particle excitation of translational and librational types of separate nano-confined H2O/D2O molecules [5,6].
The research was supported by the Russian Science Foundation, Grant 22-22-00091.
[1] Gorshunov et al. Quantum Behavior of Water Molecules Confined to Nanocavities in Gemstones. J. Physical Chemistry Letters, 4 2015 (2013)
[2] Gorshunov, et al. Incipient ferroelectricity of water molecules confined to nano-channels of beryl. Nature Communications 7, 12842 (2016).
[3] Belyanchikov et al. Fingerprints of critical phenomena in a quantum paraelectric ensemble of nanoconfined water molecules. Nano Letters (2022) https://doi.org/10.1021/acs.nanolett.2c00638
[4] Belyanchikov et al. Dielectric ordering in dipolar lattice of water in cordierite. Nature Communications. 11, 3927 (2020)
[5] Belyanchikov et al. Vibrational states of nano-confined water molecules in beryl investigated by first principles calculations and optical experiments. Physical Chemistry Chemical Physics, 19, 30740 (2017)
[6] Belyanchikov et al. Single-particle and collective excitations of polar water molecules confined in nano-pores within cordierite crystal lattice. Physical Chemistry Chemical Physics. 24, 6890-6904 (2022)
