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Title: Ice I h revisited: No proton tunneling observed in a quasielastic neutron scattering experiment

A large broadening ($${\sim}0.4\mathrm{meV}$$) of quasielastic neutron scattering (QENS) signal in $${\mathrm{H}}_{2}\mathrm{O}$$ ice $${I}_{h}$$ at $$T=5\mathrm{K}$$ was observed by Bove et al. [Phys. Rev. Lett. 103, 165901 (2009)] and explained by a model of concerted proton tunneling. This result was rather unexpected, as prior studies never showed significant mobility in water at low temperatures and ambient pressure. There were a few attempts of theoretical understanding of the effect. Recent path-integral simulations as well as quantum lattice-gauge theory supported the possibility of the collective tunneling of protons in ice $${I}_{h}$$, however other studies stated that concerted tunneling in ice $${I}_{h}$$ should have very low frequency. In this paper, we report on QENS measurements of $${\mathrm{H}}_{2}\mathrm{O}$$ ice $${I}_{h}$$ at 1.8 and 5 K by using neutron scattering spectrometers with the energy resolution similar to and four times better than the energy resolution in the original experiment of Bove and co-workers. We did not observe any QENS broadening, and the measured spectra for the ice $${I}_{h}$$ and the reference vanadium sample were almost identical. Therefore, we conclude that there is no proton tunneling in ice $${I}_{h}$$ at temperatures down to 1.8 K measurable on an energy scale of 3.5 $${\mu}\mathrm{eV}$$ and above. Finally, the literature data on low-temperature heat capacity of ice $${I}_{h}$$ support this conclusion.
Authors:
 [1] ;  [2] ;  [1] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Neutron Scattering Division
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Neutron Technologies Division
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 98; Journal Issue: 6; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
quasi-elastic neutron scattering
OSTI Identifier:
1463998
Alternate Identifier(s):
OSTI ID: 1463212