Near-infrared spectra of H2O under high pressure and high temperature: Implications for a transition from proton tunneling to hopping states

Naoki Noguchi, Kazuki Komatsu, Ayako Shinozaki, Keiji Shinoda, Hiroyuki Kagi

Research output: Contribution to journalArticle

2 Citations (Scopus)


The nature of protons in ice VII up to 368 °C and 16 GPa was investigated with synchrotron near-infrared spectroscopy. The absorption band of the first OH stretching overtone mode divided into doublet peaks above 5 GPa at room temperature, suggesting that proton tunneling occurs at the overtone level. As the temperature increased, the doublet peaks gradually reduced to a singlet. This result implies that thermally activated protons hop between the two potential minima along the oxygen-oxygen axis. A pressure-temperature diagram for the proton state was constructed from the changing band shape of the overtone mode.

Original languageEnglish
Pages (from-to)509-513
Number of pages5
JournalSpectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
Publication statusPublished - Dec 10 2014



  • High pressure and high temperature
  • Ice
  • Near-infrared spectroscopy
  • Proton hopping
  • Proton tunneling

ASJC Scopus subject areas

  • Analytical Chemistry
  • Atomic and Molecular Physics, and Optics
  • Instrumentation
  • Spectroscopy

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