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Studies on the Phonon Dynamics and Structural Phase Transitions in Clathrate Hydrates by Raman and X-ray Scattering

Research Project

Project/Area Number 06640668
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field Physical chemistry
Research InstitutionToyo University

Principal Investigator

WADA Noboru  Toyo Univ., Fac.of Engineering, Professor, 工学部, 教授 (40256772)

Project Period (FY) 1994 – 1995
Project Status Completed (Fiscal Year 1995)
Budget Amount *help
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1994: ¥1,200,000 (Direct Cost: ¥1,200,000)
KeywordsClathrate Hydrate / Raman Scattering / X-ray Diffraction / フラロール
Research Abstract

The purpose of this research is to study the phonon dynamics and structural phase transitions in clathrate hydrates. In particular, we are interested in the changes of the hydrogen bonds of water molecules upon the transitions and the molecular field around the guest molecule.
First, water solusion of fullerol C_<60> (OH) _X is studied. The solution is found, however, to contain some chemical impurities such as NaOH and tetrabutylammoniumhydroxide. Though, at this time, we are not successful in completely characterizing the samples, we hope to purify C_<60> (OH) _X and conduct more quantitative experiments on the fullerol clathrate hydrate system.
Second, tetrahydrofuran (THF) clathrate hydrate and liquid THF・17H_2O are studied by Raman spectroscopy. From the frequencies of O-H vibrations as well as the hydrogen bond vibrations, we suggest that the strength of the H_2O host network in liquid THF・17H_2O is about the same as that in water. Upon the formation of the hydrate, the H_2O host network becomes stronger. The frequencies of the C-O-C and CH_2 vibrations of THF molecules in THF hydrate are found to be higher than in pure THF liquid. The depolarization ratios of the C-O-C symmetric and asymmetric stretching vibrations vary drastically as the THF molecules are in different physical states, such as in pure THF liquid, in liquid water, and in the cages of the hydrate. We suggest that THF molecule in THF hydrate is more like a free THF molecule in the gas phase, in which the five-member ring of THF molecule is buckled. The five-member ring of THF molecule is more planar when THF is liquid THF・17H_2O.An Ag-like mode at 900cm^<-1>, which is not observable in either pure water or pure THF liquid, is observed in the Raman spectra of liquid THF・17H_2O and THF hydrate.

Report

(3 results)
  • 1995 Annual Research Report   Final Research Report Summary
  • 1994 Annual Research Report
  • Research Products

    (3 results)

All Other

All Publications (3 results)

  • [Publications] Chung-Hua Qiu, N.Wada, and E.D.Sloan, Jr.: "Raman Scattering Studies of Tetrahydrofuran (THF) Clathrate Hydrate and its Liquid State" (to be submitted).

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] K.Shida, N.Wada, A.Shoji, and Y.Yosida: "Raman and IR Spectra of Fullerols C_<60> (OH)_x" Bull.Amer.Phys.Soc.40. 174 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] K.Shida,N.Wada,他2名: "Raman and IR spectra of fullerols C_<60>(OH)_X" Bulletin of The American Physical Society. 40. 174-174 (1995)

    • Related Report
      1994 Annual Research Report

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Published: 1994-04-01   Modified: 2016-04-21  

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