ID | 118577 |
著者 |
Shiraishi, Yui
Tokushima University
Kageyama, Maho
Tokushima University
Yokoi, Yuu
Tokushima University
Kurohama, Saki
Tokushima University
Okada, Natsuki
Tokushima University
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資料タイプ |
学術雑誌論文
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抄録 | The pressure-induced amorphization (PIA) of ice and clathrate hydrates occurs at temperatures significantly below their melting and decomposition points. The PIA of type I clathrate hydrates containing methane and ethane as guest molecules was investigated using Raman and infrared (IR) spectroscopy. With isothermal compression at 100 K, methane hydrate (MH) underwent PIA at 2–3.5 GPa, whereas ethane hydrate (EH) underwent PIA at 4.0–5.5 GPa. The type I clathrate structure consists of small (512) and large (51262) cages. The Raman results revealed that the collapsed small and large cages in the amorphous forms of MH and EH were not distinguishable. The collapsed cages, including the methane and ethane molecules, were similar to the small and large cages, respectively. Their water networks were folded or expanded during the PIA process so that the cavity sizes of the collapsed cages were compatible with those of the guest molecules. Peaks in the IR spectra of crystalline MH assignable to the ro-vibrational transition of methane in large cages were observed in the C–H stretching wavenumber region below 40 K. The ro-vibrational IR band disappeared after amorphization, suggesting that the rotational motion of the methane molecule in the large cage was frozen by the collapse, as reported in previous dielectric spectroscopic and simulation studies. This study contributes to a better understanding of the changes in the local structure around guest molecules during PIA and the dynamics of the guest molecules.
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掲載誌名 |
Physical Chemistry Chemical Physics
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ISSN | 14639076
14639084
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cat書誌ID | AA11301773
AA11723355
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出版者 | The Royal Society of Chemistry
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巻 | 25
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号 | 33
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開始ページ | 22161
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終了ページ | 22170
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発行日 | 2023-08-07
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EDB ID | |
出版社版DOI | |
出版社版URL | |
フルテキストファイル | |
言語 |
eng
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著者版フラグ |
著者版
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部局 |
理工学系
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