The isotope effect and orientational potentials of methane molecules in gas hydrates
We report an inelastic neutron scattering experiment at T=2 K of a fully deuterated methane hydrate CD4⋅5.75 D2O. In the experiment the J=0→J=1 rotational transition of an almost free quantum CD4 rotor at an energy transfer of 0.4 meV has been found. No line splitting due to the two different kinds...
Published in: | The Journal of Chemical Physics |
---|---|
Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
AIP Publishing
2001
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1063/1.1344922 https://pubs.aip.org/aip/jcp/article-pdf/114/9/4160/10834434/4160_1_online.pdf |
id |
craippubl:10.1063/1.1344922 |
---|---|
record_format |
openpolar |
spelling |
craippubl:10.1063/1.1344922 2024-02-11T10:05:49+01:00 The isotope effect and orientational potentials of methane molecules in gas hydrates Gutt, Christian Press, Werner Hüller, Alfred Tse, John S. Casalta, Helene 2001 http://dx.doi.org/10.1063/1.1344922 https://pubs.aip.org/aip/jcp/article-pdf/114/9/4160/10834434/4160_1_online.pdf en eng AIP Publishing The Journal of Chemical Physics volume 114, issue 9, page 4160-4170 ISSN 0021-9606 1089-7690 Physical and Theoretical Chemistry General Physics and Astronomy journal-article 2001 craippubl https://doi.org/10.1063/1.1344922 2024-01-26T09:49:38Z We report an inelastic neutron scattering experiment at T=2 K of a fully deuterated methane hydrate CD4⋅5.75 D2O. In the experiment the J=0→J=1 rotational transition of an almost free quantum CD4 rotor at an energy transfer of 0.4 meV has been found. No line splitting due to the two different kinds of cages, which are occupied by the methane molecules in the host lattice, has been found. Using a simple electrostatic model of the orientational interaction between the methane molecules and the water molecules in the host lattice we are able to explain the measured spectra of both the deuterated and protonated samples. The intrinsic linewidth found for the rotational transition in deuterated and protonated samples can be attributed to the frozen in disorder of the water dipole moments in the cages. The contribution of the van der Waals interaction has also been calculated on the basis of empirical atom–atom interaction parameters and has been found to be one order of magnitude smaller than the electrostatic interaction. In addition the calculated orientational scattering length density of the CD4 molecules is found to be in good agreement with experimental values. It is shown, that previous diffraction experiments lead to only limited information about the orientational distribution function due to the proton disorder. Article in Journal/Newspaper Methane hydrate AIP Publishing The Journal of Chemical Physics 114 9 4160 4170 |
institution |
Open Polar |
collection |
AIP Publishing |
op_collection_id |
craippubl |
language |
English |
topic |
Physical and Theoretical Chemistry General Physics and Astronomy |
spellingShingle |
Physical and Theoretical Chemistry General Physics and Astronomy Gutt, Christian Press, Werner Hüller, Alfred Tse, John S. Casalta, Helene The isotope effect and orientational potentials of methane molecules in gas hydrates |
topic_facet |
Physical and Theoretical Chemistry General Physics and Astronomy |
description |
We report an inelastic neutron scattering experiment at T=2 K of a fully deuterated methane hydrate CD4⋅5.75 D2O. In the experiment the J=0→J=1 rotational transition of an almost free quantum CD4 rotor at an energy transfer of 0.4 meV has been found. No line splitting due to the two different kinds of cages, which are occupied by the methane molecules in the host lattice, has been found. Using a simple electrostatic model of the orientational interaction between the methane molecules and the water molecules in the host lattice we are able to explain the measured spectra of both the deuterated and protonated samples. The intrinsic linewidth found for the rotational transition in deuterated and protonated samples can be attributed to the frozen in disorder of the water dipole moments in the cages. The contribution of the van der Waals interaction has also been calculated on the basis of empirical atom–atom interaction parameters and has been found to be one order of magnitude smaller than the electrostatic interaction. In addition the calculated orientational scattering length density of the CD4 molecules is found to be in good agreement with experimental values. It is shown, that previous diffraction experiments lead to only limited information about the orientational distribution function due to the proton disorder. |
format |
Article in Journal/Newspaper |
author |
Gutt, Christian Press, Werner Hüller, Alfred Tse, John S. Casalta, Helene |
author_facet |
Gutt, Christian Press, Werner Hüller, Alfred Tse, John S. Casalta, Helene |
author_sort |
Gutt, Christian |
title |
The isotope effect and orientational potentials of methane molecules in gas hydrates |
title_short |
The isotope effect and orientational potentials of methane molecules in gas hydrates |
title_full |
The isotope effect and orientational potentials of methane molecules in gas hydrates |
title_fullStr |
The isotope effect and orientational potentials of methane molecules in gas hydrates |
title_full_unstemmed |
The isotope effect and orientational potentials of methane molecules in gas hydrates |
title_sort |
isotope effect and orientational potentials of methane molecules in gas hydrates |
publisher |
AIP Publishing |
publishDate |
2001 |
url |
http://dx.doi.org/10.1063/1.1344922 https://pubs.aip.org/aip/jcp/article-pdf/114/9/4160/10834434/4160_1_online.pdf |
genre |
Methane hydrate |
genre_facet |
Methane hydrate |
op_source |
The Journal of Chemical Physics volume 114, issue 9, page 4160-4170 ISSN 0021-9606 1089-7690 |
op_doi |
https://doi.org/10.1063/1.1344922 |
container_title |
The Journal of Chemical Physics |
container_volume |
114 |
container_issue |
9 |
container_start_page |
4160 |
op_container_end_page |
4170 |
_version_ |
1790603013896798208 |