Indication of tunneling state of hydrogen atom in hydrogen-bonded material 5-bromo-9-hydroxyphenalenon studied by X-ray and neutron diffractions

Ryoji Kiyanagi, Hiroyuki Kimura, Masashi Watanabe, Yukio Noda, Tomoyuki Mochida, Tadashi Sugawara

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

The dielectric material with an isolated hydrogen-bond, 5-bromo-9-hydroxyphenalenon, was studied by means of neutron and X-ray diffractions in the temperature range between 300 and 10 K. Analyses on nuclear and electron density distributions revealed a discrepancy between the two distributions of the hydrogen atom in the hydrogen-bond region, leading to a local electronic dipole moment. Both a least-square structure analysis and the density distribution analysis by the maximum entropy method confirmed that the hydrogen atom occupies two equivalent sites near the center of the hydrogen-bond through the whole temperature range, even at the lowest temperature measured, 10 K. This feature, together with previous results on calorimetric, incoherent neutron scattering and far-infrared spectrum measurements, concludes that the hydrogen atom in the hydrogen-bond is in a tunneling state over the two sites. Consequently, 5-bromo-9-hydroxyphenalenon was experimentally identified as a quantum paraelectric material.

Original languageEnglish
Article number064602
Journaljournal of the physical society of japan
Volume77
Issue number6
DOIs
Publication statusPublished - 2008 Jun

Keywords

  • Isolated hydrogen-bonded system
  • Neutron diffraction
  • Structural analysis
  • X-ray diffraction

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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