Low-Frequency Raman Scattering in a Xe Hydrate

The physics of gas hydrates are rich in interesting phenomena such as anomalies for thermal conductivity, self-preservation effects for decomposition, and others. Some of these phenomena are presumably attributed to the resonance interaction of the rattling motions of guest molecules or atoms with t...

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Bibliographic Details
Published in:The journal of physical chemistry. B 2013-09, Vol.117 (36), p.10686-10690
Main Authors: Adichtchev, S. V, Belosludov, V. R, Ildyakov, A. V, Malinovsky, V. K, Manakov, A. Yu, Subbotin, O. S, Surovtsev, N. V
Format: Article
Language:English
Subjects:
Bands
Decomposition
Gas hydrates
Hydrates
Mathematical analysis
Mathematical models
Raman scattering
Resonance interactions
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Summary:The physics of gas hydrates are rich in interesting phenomena such as anomalies for thermal conductivity, self-preservation effects for decomposition, and others. Some of these phenomena are presumably attributed to the resonance interaction of the rattling motions of guest molecules or atoms with the lattice modes. This can be expected to induce some specific features in the low-frequency (THz) vibrational response. Here we present results for low-frequency Raman scattering in a Xe hydrate, supported by numerical calculations of vibrational density of states. A number of narrow lines, located in the range from 18 to 90 cm–1, were found in the Raman spectrum. Numerical calculations confirm that these lines correspond to resonance modes of the Xe hydrate. Also, low-frequency Raman scattering was studied during gas hydrate decomposition, and two scenarios were observed. The first one is the direct decomposition of the Xe hydrate to water and gas. The second one is the hydrate decomposition to ice and gas with subsequent melting of ice. In the latter case, a transient low-frequency Raman band is observed, which is associated with low-frequency bands (e.g., boson peak) of disordered solids.
ISSN:1520-6106
1520-5207
DOI:10.1021/jp406086j