Ice $I_h$ revisited: No proton tunneling observed in a quasielastic neutron scattering experiment

Journal Article · 07 August 2018 · Physical Review B

DOI: https://doi.org/10.1103/PhysRevB.98.064301 · OSTI ID:1463998

Kolesnikov, Alexander I. ^[1]; Ehlers, Georg ^[2]; Mamontov, Eugene ^[1]; Podlesnyak, Andrey ^[1]

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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

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.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1463998
• Alternate ID(s): OSTI ID: 1463212
• Journal Information: Physical Review B, Vol. 98, Issue 6; ISSN 2469-9950
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English