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Title: The quantum nature of the OH stretching mode in ice and water probed by neutron scattering experiments

Abstract

The OH stretching vibrational spectrum of water was measured in a wide range of temperatures across the triple point, 269 K < T < 296 K, using Inelastic Neutron Scattering (INS). The hydrogen projected density of states and the proton mean kinetic energy, _OH, were determined for the first time within the framework of a harmonic description of the proton dynamics. We found that in the liquid the value of _OH is nearly constant as a function of T, indicating that quantum effects on the OH stretching frequency are weakly dependent on temperature. In the case of ice, ab initio electronic structure calculations, using non-local van der Waals functionals, provided _OH values in agreement with INS experiments. We also found that the ratio of the stretching (_OH) to the total (_exp) kinetic energy, obtained from the present measurements, increases in going from ice, where hydrogen bonding is the strongest, to the liquid at ambient conditions and then to the vapour phase, where hydrogen bonding is the weakest. The same ratio was also derived from the combination of previous deep inelastic neutron scattering data, which does not rely upon the harmonic approximation, and the present measurements. We found that the ratiomore » of stretching to the total kinetic energy shows a minimum in the metastable liquid phase. This finding suggests that the strength of intermolecular interactions increases in the supercooled phase, with respect to that in ice, contrary to the accepted view that supercooled water exhibits weaker hydrogen bonding than ice.« less

Authors:
 [1];  [1];  [1];  [2];  [2];  [1]
  1. ORNL
  2. University of California, Davis
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1095761
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 139; Journal Issue: 7
Country of Publication:
United States
Language:
English

Citation Formats

Senesi, Roberto, Flammini, Davide, Kolesnikov, Alexander I, Murray, Eamonn D., Galli, Giulia, and Andreani, Carla. The quantum nature of the OH stretching mode in ice and water probed by neutron scattering experiments. United States: N. p., 2013. Web. doi:10.1063/1.4818494.
Senesi, Roberto, Flammini, Davide, Kolesnikov, Alexander I, Murray, Eamonn D., Galli, Giulia, & Andreani, Carla. The quantum nature of the OH stretching mode in ice and water probed by neutron scattering experiments. United States. doi:10.1063/1.4818494.
Senesi, Roberto, Flammini, Davide, Kolesnikov, Alexander I, Murray, Eamonn D., Galli, Giulia, and Andreani, Carla. 2013. "The quantum nature of the OH stretching mode in ice and water probed by neutron scattering experiments". United States. doi:10.1063/1.4818494.
@article{osti_1095761,
title = {The quantum nature of the OH stretching mode in ice and water probed by neutron scattering experiments},
author = {Senesi, Roberto and Flammini, Davide and Kolesnikov, Alexander I and Murray, Eamonn D. and Galli, Giulia and Andreani, Carla},
abstractNote = {The OH stretching vibrational spectrum of water was measured in a wide range of temperatures across the triple point, 269 K < T < 296 K, using Inelastic Neutron Scattering (INS). The hydrogen projected density of states and the proton mean kinetic energy, _OH, were determined for the first time within the framework of a harmonic description of the proton dynamics. We found that in the liquid the value of _OH is nearly constant as a function of T, indicating that quantum effects on the OH stretching frequency are weakly dependent on temperature. In the case of ice, ab initio electronic structure calculations, using non-local van der Waals functionals, provided _OH values in agreement with INS experiments. We also found that the ratio of the stretching (_OH) to the total (_exp) kinetic energy, obtained from the present measurements, increases in going from ice, where hydrogen bonding is the strongest, to the liquid at ambient conditions and then to the vapour phase, where hydrogen bonding is the weakest. The same ratio was also derived from the combination of previous deep inelastic neutron scattering data, which does not rely upon the harmonic approximation, and the present measurements. We found that the ratio of stretching to the total kinetic energy shows a minimum in the metastable liquid phase. This finding suggests that the strength of intermolecular interactions increases in the supercooled phase, with respect to that in ice, contrary to the accepted view that supercooled water exhibits weaker hydrogen bonding than ice.},
doi = {10.1063/1.4818494},
journal = {Journal of Chemical Physics},
number = 7,
volume = 139,
place = {United States},
year = 2013,
month = 1
}
  • Inelastic x-ray and neutron scattering were used to measure two matching lattice excitations on the [010] zone boundary in {alpha}-uranium. The excitations have the same polarization and reciprocal-space structure, but one has energy consistent with the thermal activation energy of the other, indicating that it creates the mode. The implied mechanism, where a mode is created by an amplitude fluctuation that mirrors the mode itself, is consistent with an intrinsically localized mode (ILM), and this is supported by thermodynamic data. The reciprocal-space structure, however, indicates a mode that is extended along its polarization direction, [010], and yet fully localized alongmore » a perpendicular direction, [001]. An enhancement of the thermal but not electrical conductivity with mode activation also suggests that these modes are more mobile than conventional ILMs. The behavior is, however, qualitatively similar to that predicted for ILMs on two-dimensional hexagonal lattices, where in-plane localization has been shown to be extended over more than ten discrete units, and the modes can be highly mobile.« less
  • It is established for the first time that the intensities of deformation and valence Raman scattering (RS) bands in water vary oppositely in the processes of degassing and crystallising. Water degassing shifts the centre of a valence OH band to higher frequencies by approximately 2 cm{sup -1}, which points to a reduced contribution of structural complexes to the RS spectrum. (letters)
  • A Comment on the Letter by H.-Q. Ding and M. S. Makivic, Phys. Rev. Lett. 64, 1449 (1990).
  • Correlation functions of the spin-1/2 2D Heisenberg antiferromagnet at low temperatures are computed via a large-scale Monte Carlo simulation on 128{times}128 lattices. The correlation length is found to be accurately described by the exponentially divergent form typical of classical Heisenberg spins in two dimensions. The large correlation lengths measured are directly compared with the neutron-scattering experiments on La{sub 2}CuO{sub 4}. The excellent fit provides a first-principles determination of the exchange coupling: {ital J}=1450 {plus minus}30 K.
  • Polarised neutron diffraction experiments conducted at 4.2 K on Cs{sub 3}CoCl{sub 5} crystals have been analysed by using a four-dimensional model Hilbert space made of ab initio n-electron wave functions of the CoCl{sub 4}{sup 2-} molecular ion. Two spin-orbit mixing coefficients and several configuration interaction coefficients have been optimized by fitting calculated magnetic structure factors to experimental ones, to obtain the best ensemble density operator that is representable in the model space. A goodness of fit, {chi}{sup 2}, less then 1 has been obtained for the first time for the two experimental data sets available. In the present article, themore » optimized density operators are used to calculate the magnetic field densities that are the genuine observables probed in neutron diffraction experiments. Density maps of such observables are presented for the first time and numerical details are provided. The respective contributions of spin density and orbital current to the magnetic field density are analyzed.« less