2007 Fiscal Year Final Research Report Summary
High-pressure study on symmetric hydrogen bond in gas hydrates
| Project/Area Number |
18540314
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Condensed matter physics I
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| Research Institution | Gifu University |
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Principal Investigator |
SASAKI Shigeo Gifu University, Fac. of Engineering, Associate Professor (30196159)
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| Co-Investigator(Kenkyū-buntansha) |
KUME Tetsuji Gifu University, Fac. of Engineering, Assistant Professor (30293541)
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| Project Period (FY) |
2006 – 2007
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| Keywords | methane hydrate / molecular solid / hydrogen bond / Raman scattering / diamond anvil cell / high-pressure science / optical property / condensed matter |
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| Research Abstract |
In the "filled icg" phase of methane hydrate, it is theoretically estimated that the pressure-induced symmetrization of hydrogen bond occurs at 40 GPa which is 20 GPa lower than that of ice-VII. However, until now there is no experimental evidence for symmetric hydrogen bond of methane hydrate, because no one observed the O-H stretching vibrational peak in "filled ice" phase of methane hydrate. Therefore, the purposes of this research are to grow a single crystalline "filled ice" of methane hydrate and to explore the symmetrization of hydrogen bond in "filled ice" phase of methane hydrate using high-pressure Raman spectroscopy.
We succeeded in growing small single crystals of "filled ice" of methane hydrate using a temperature controlled high-pressure diamond anvil cell. By applying the high-pressure Raman spectroscopy to the above single crystals, we finally observed the O-H stretching vibration in "filled ice" phase above 10 GPa. Although we did not still observed the symmetric hydrogen bond directly, we found the possibility that the symmetrization of hydrogen bond in methane hydrate should occur at about 50 GPa from the pressure dependence of Raman frequency shifts for O-H stretching mode at pressures from 10 to 15 GPa.
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