Broad-Band Spectroscopy of Nanoconfined Water Molecules
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We have performed broad-band spectroscopic investigations of vibrational and relaxational excitations of water molecules confined to nanocages within artificial beryl and mineral cordierite crystals. Signatures of quantum critical phenomena within the H2O molecular network are registered in beryl. In cordierite, a density functional analysis is applied to reconstruct the potential energy landscape experienced by H2O molecules, revealing a pronounced anisotropy with a potential well of about 10 meV for the molecular dipole moment aligned along the b-axis. This anisotropy leads to a strongly temperature dependent and anisotropic relaxational response of the dipoles at radiofrequencies with the activation energies corresponding to the barriers of the rotational potential. At T ≈ 3 K, we identify signatures of a transition into a glassy state composed by clusters of H2O dipoles. Rich set of anisotropic and temperature-dependent excitations are observed in the terahertz frequency range which we associate with rotational/translational vibrations.
KeywordsNanoconfined water Spectroscopy Quantum criticality Ferroelectricity
We thank G. Untereiner for careful crystal preparation. The study was funded by RFBR (projects 18-32-20186 and 18-32-00286), by RF Ministry of Science and Higher Education (State assignment FSRC «Crystallography and Photonics» and Program 5-100), Deutsche Forschungsgemeinschaft (DR228/61-1) and by the Stuttgart/Ulm Research Center for Integrated Quantum Science and Technology (IQST). E.U. acknowledges the support of the European Social Fund and of the Ministry of Science Research and the Arts of Baden-Württemberg. M.S. and SK acknowledge Czech Science Foundation (Project No. 15-08389S) and MŠMT (Project No. SOLID21—CZ.02.1.01/0.0/0.0/16_019/0000760).
Conflict of Interest
The authors declare that they have no conflict of interest.
- 2.Gibbs, G.V.: The polymorphism of cordierite I: the crystal structure of low cordierite. Am. Miner. 51, 1068–1087 (1966)Google Scholar
- 3.Thomas, V.G., Klyakhin, V.A.: The specific features of beryl doping by chromium under hydrothermal conditions. In: Sobolev, N.V. (ed.) Mineral Forming in Endogenic Processes, pp. 60–67. Nauka, Novosibirsk (1987) (in Russian)Google Scholar
- 7.Khmelnitskii, D.E., Shneerson, V.L.: Low-temperature displacement-type phase transition in crystals. Sov. Phys.: Solid State 13, 687 (1971)Google Scholar
- 8.Khmelnitskii, D.E., Shneerson, V.L.: Phase transitions of the displacement type in crystals at very low temperatures. Sov. Phys. JETP 37, 164 (1973)Google Scholar