Ortho–para conversion in the solid hydrogens at high pressures
At low pressures the ortho–para conversion in H₂ and D₂ is a slow process governed by the magnetic dipole interaction of nuclear magnetic moments, phonons being the main energy sink. As the pressure is raised to a few GPa and the Debye temperature increases substantially, the conversion energy finds...
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| Veröffentlicht in: | Физика низких температур |
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| Datum: | 2003 |
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| Sprache: | Englisch |
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Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України
2003
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| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Zitieren: | Ortho–para conversion in the solid hydrogens at high pressures / M.A. Strzhemechny, R.J. Hemley // Физика низких температур. — 2003. — Т. 29, № 9-10. — С. 941-946. — Бібліогр.: 30 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1862715739161493504 |
|---|---|
| author | Strzhemechny, M.A. Hemley, R.J. |
| author_facet | Strzhemechny, M.A. Hemley, R.J. |
| citation_txt | Ortho–para conversion in the solid hydrogens at high pressures / M.A. Strzhemechny, R.J. Hemley // Физика низких температур. — 2003. — Т. 29, № 9-10. — С. 941-946. — Бібліогр.: 30 назв. — англ. |
| collection | DSpace DC |
| container_title | Физика низких температур |
| description | At low pressures the ortho–para conversion in H₂ and D₂ is a slow process governed by the magnetic dipole interaction of nuclear magnetic moments, phonons being the main energy sink. As the pressure is raised to a few GPa and the Debye temperature increases substantially, the conversion energy finds itself in an area where phonon states are depleted and conversion slows down. The recent Raman and NMR experiments showed that the conversion rate in H₂ after an initial slowdown predicted by theory increases immensely. As for solid D₂, conversion rates have apparently not yet been directly measured under pressure. In order to explain the anomaly observed in H₂, we have suggested a new conversion mechanism, in which the basic conversion-producing interaction only initiates conversion whereas the energy is removed by rotational excitations via the stronger electric quadrupole-quadrupole interaction. Estimated conversion rates are in good qualitative agreement with available experimental observations. Here we extend the theory to solid D₂ taking into account the differences between H₂ and D₂ in the molecular and solid-state parameters. The new libron-mediated channel is predicted to result for D₂ in conversion rates under pressure that are by an order of magnitude larger than at P = 0.
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| first_indexed | 2025-12-07T18:00:14Z |
| format | Article |
| fulltext | |
| id | nasplib_isofts_kiev_ua-123456789-128907 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 0132-6414 |
| language | English |
| last_indexed | 2025-12-07T18:00:14Z |
| publishDate | 2003 |
| publisher | Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України |
| record_format | dspace |
| spelling | Strzhemechny, M.A. Hemley, R.J. 2018-01-14T12:38:35Z 2018-01-14T12:38:35Z 2003 Ortho–para conversion in the solid hydrogens at high pressures / M.A. Strzhemechny, R.J. Hemley // Физика низких температур. — 2003. — Т. 29, № 9-10. — С. 941-946. — Бібліогр.: 30 назв. — англ. 0132-6414 PACS: 61.10.-i, 61.66.-f, 65.70.+y https://nasplib.isofts.kiev.ua/handle/123456789/128907 At low pressures the ortho–para conversion in H₂ and D₂ is a slow process governed by the magnetic dipole interaction of nuclear magnetic moments, phonons being the main energy sink. As the pressure is raised to a few GPa and the Debye temperature increases substantially, the conversion energy finds itself in an area where phonon states are depleted and conversion slows down. The recent Raman and NMR experiments showed that the conversion rate in H₂ after an initial slowdown predicted by theory increases immensely. As for solid D₂, conversion rates have apparently not yet been directly measured under pressure. In order to explain the anomaly observed in H₂, we have suggested a new conversion mechanism, in which the basic conversion-producing interaction only initiates conversion whereas the energy is removed by rotational excitations via the stronger electric quadrupole-quadrupole interaction. Estimated conversion rates are in good qualitative agreement with available experimental observations. Here we extend the theory to solid D₂ taking into account the differences between H₂ and D₂ in the molecular and solid-state parameters. The new libron-mediated channel is predicted to result for D₂ in conversion rates under pressure that are by an order of magnitude larger than at P = 0. This work was supported by the CRDF (grant UP2-2445-KH-02) and NSF/DMR. The authors thank A. F. Goncharov for providing his unpublished results. M.A.S. also thanks Irina Legchenkova for technical assistance. en Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України Физика низких температур High-Pressure Studies Ortho–para conversion in the solid hydrogens at high pressures Article published earlier |
| spellingShingle | Ortho–para conversion in the solid hydrogens at high pressures Strzhemechny, M.A. Hemley, R.J. High-Pressure Studies |
| title | Ortho–para conversion in the solid hydrogens at high pressures |
| title_full | Ortho–para conversion in the solid hydrogens at high pressures |
| title_fullStr | Ortho–para conversion in the solid hydrogens at high pressures |
| title_full_unstemmed | Ortho–para conversion in the solid hydrogens at high pressures |
| title_short | Ortho–para conversion in the solid hydrogens at high pressures |
| title_sort | ortho–para conversion in the solid hydrogens at high pressures |
| topic | High-Pressure Studies |
| topic_facet | High-Pressure Studies |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/128907 |
| work_keys_str_mv | AT strzhemechnyma orthoparaconversioninthesolidhydrogensathighpressures AT hemleyrj orthoparaconversioninthesolidhydrogensathighpressures |