Dynamical Crossover in Hot Dense Water: The Hydrogen Bond Role

Year: 2016

Authors: Ranieri U., Giura P., Gorelli F., Santoro M., Klotz S., Gillet P., Paolasini L., Koza MM., Bove LE.

Autors Affiliation: Ecole Polytech Fed Lausanne, ICMP, EPSL, Stn 3, CH-1015 Lausanne, Switzerland; Inst Laue Langevin, 71,Ave Martyrs,BP 156, F-38042 Grenoble 9, France; Univ Paris 06, CNRS, UMR 7590, Inst Mineral Phys Mat & Cosmochim, 4 Pl Jussieu, F-75252 Paris, France;‎ CNR, INO, Via N Carrara 1, I-50019 Sesto Fiorentino, Italy; LENS, European Lab Non Linear Opt, Via N Carrara 1, I-50019 Sesto Fiorentino, Italy; ESRF, 71,Ave Martyrs,CS 40220, F-38043 Grenoble 9, France

Abstract: We investigate the terahertz dynamics of liquid H2O as a function of pressure along the 450 K isotherm, by coupled quasielastic neutron scattering and inelastic X-ray scattering experiments. The pressure dependence of the single molecule dynamics is anomalous in terms of both microscopic translation and rotation. In particular, the Stokes-Einstein-Debye equations are shown to be violated in hot water compressed to the GPa regime. The dynamics of the hydrogen bond network is only weakly affected by the pressure variation. The time scale of the structural relaxation driving the collective dynamics increases by a mere factor of 2 along the investigated isotherm, and the structural relaxation strength turns out to be almost pressure independent. Our results point at the persistence of the hydrogen bond network in hot dense water up to ice VII crystallization, thus questioning the long-standing perception that hydrogen bonds are broken in liquid water under the effect of compression.

Journal/Review: JOURNAL OF PHYSICAL CHEMISTRY B

Volume: 120 (34)      Pages from: 9051  to: 9059

More Information: This work was supported by the Swiss National Science Foundation through FNS Grant 200021-149847, and by the French state funds managed by ANR within the Blanc International programme PACS (reference ANR-13-IS04-0006-01) and the Investissements d´Avenir programme (reference ANR-11-IDEX-0004-02) and more specifically within the framework of the Cluster of Excellence MATeriaux Interfaces Surfaces Environnement (MATISSE) led by Sorbonne Universites. We acknowledge the European Synchrotron Radiation Facility for provision of beam time at ID28, and B. Wehinger, T. Forrest, D. Gambetti, A. Bossak, and M. Krisch for their valuable advice and technical assistance during the IXS experiment. Our thanks also go to the Institut Laue-Langevin for provision of beam time at IN6, and to Claude Payre, Richard Ammer and Jean-Luc Laborier for technical assistance during the QENS experiment. Finally, we are indebted to R. Pick for his many stimulating comments and valuable help and advice in the interpretation of results, and to J. Teixeira, F. Datchi, R. Gaal, and E. H. Abramson for the useful discussions they initiated.
KeyWords: NEUTRON-SCATTERING SPECTRA; STOKES-EINSTEIN RELATION; LIQUID WATER; PRESSURE-DEPENDENCE; MOLECULAR-DYNAMICS; TRANSITION; RELAXATION; VISCOSITY; BEHAVIOR; MOTIONS
DOI: 10.1021/acs.jpcb.6b04142

Citations: 15
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