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

Article

关键词: HEXAGONAL ICE;    WATER;    HYDROGEN;    VISUALIZATION;    DEUTERATION;   

DOI  :  10.1103/PhysRevB.98.064301

来源: SCIE

【 摘 要 】

A large broadening (similar to 0.4meV) of quasielastic neutron scattering (QENS) signal in H2O ice I-h at T = 5K 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. Here, we report on QENS measurements of H2O 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 eV and above. The literature data on low-temperature heat capacity of ice I-h support this conclusion.

【 授权许可】

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