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International Conference on Gas Hydrates (ICGH) (6th : 2008)

NEUTRON SCATTERING MEASUREMENTS OF THE HYDROGEN DYNAMICS IN CLATHRATES HYDRATES. Ulivi, Lorenzo; Celli, Milva; Giannasi, Alessandra; Zoppi, Marco; Ramirez-Cuesta, A.J.

Abstract

The hydrogen molecule dynamics in tetrahydrofuran-H2-H2O clathrate hydrate has been studied by high-resolution inelastic neutron scattering and Raman light scattering. Several intense bands in the neutron spectrum are observed that are due to H2 molecule excitations. These are rotational transitions, center-of-mass translational transitions (rattling) of either para- or ortho-H2, and combinations of rotations and center-of-mass transitions. The rattling of the H2 molecule is a paradigmatic example of the motion of a quantum particle in a non-harmonic three-dimensional potential well. Both the H2 rotational transition and the fundamental of the rattling transition split into triplets. Raman spectra show a similar splitting of the S0(0) rotational transition, due to a significant anisotropy of the potential with respect to the orientation of the molecule in the cage. The comparison of our experimental values for the transition frequencies to a recent quantum mechanical calculation gives qualitative agreement, but shows some significant difference.

Item Metadata

Title
NEUTRON SCATTERING MEASUREMENTS OF THE HYDROGEN DYNAMICS IN CLATHRATES HYDRATES.
Creator
Ulivi, Lorenzo; Celli, Milva; Giannasi, Alessandra; Zoppi, Marco; Ramirez-Cuesta, A.J.
Contributor
University of British Columbia. Department of Chemical and Biological Engineering; International Conference on Gas Hydrates (6th : 2008 : Vancouver, B.C.)
Date Issued
2008-07
Description
The hydrogen molecule dynamics in tetrahydrofuran-H2-H2O clathrate hydrate has been studied by high-resolution inelastic neutron scattering and Raman light scattering. Several intense bands in the neutron spectrum are observed that are due to H2 molecule excitations. These are rotational transitions, center-of-mass translational transitions (rattling) of either para- or ortho-H2, and combinations of rotations and center-of-mass transitions. The rattling of the H2 molecule is a paradigmatic example of the motion of a quantum particle in a non-harmonic three-dimensional potential well. Both the H2 rotational transition and the fundamental of the rattling transition split into triplets. Raman spectra show a similar splitting of the S0(0) rotational transition, due to a significant anisotropy of the potential with respect to the orientation of the molecule in the cage. The comparison of our experimental values for the transition frequencies to a recent quantum mechanical calculation gives qualitative agreement, but shows some significant difference.
Extent
172571 bytes
Subject
Gas hydrates; Hydrogen clathrates; Neutron scattering; Raman spectroscopy.; Tetrahydrofuran; Hydrogen
Genre
Conference Paper
Type
Text
File Format
application/pdf
Language
eng
Date Available
2008-07-21
Provider
Vancouver : University of British Columbia Library
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International
DOI
10.14288/1.0041004
URI
http://hdl.handle.net/2429/1054
Affiliation
Non UBC
Citation
Ulivi, Lorenzo; Celli, Milva; Giannasi, Alessandra; Zoppi, Marco; Ramirez-Cuesta, A.J. 2008. NEUTRON SCATTERING MEASUREMENTS OF THE HYDROGEN DYNAMICS IN CLATHRATES HYDRATES. Proceedings of the 6th International Conference on Gas Hydrates (ICGH 2008), Vancouver, British Columbia, CANADA, July 6-10, 2008.
Peer Review Status
Unreviewed
Copyright Holder
Ulivi, Lorenzo
Rights URI
http://creativecommons.org/licenses/by-nc-nd/4.0/
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DSpace

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Attribution-NonCommercial-NoDerivatives 4.0 International