Spin-symmetry conversion in methyl rotors induced by tunnel resonance at low temperature
Field-cycling NMR in the solid state at low temperature (4.2 K) has been employed to measure the tunneling spectra of methyl (CH3) rotors in phenylacetone and toluene. The phenomenon of tunnel resonance reveals anomalies in 1H magnetization from which the following tunnel frequencies have been deter...
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| Format: | Article |
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American Institute of Physics
2014
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| Online Access: | https://eprints.nottingham.ac.uk/3274/ |
| _version_ | 1848790991175155712 |
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| author | Zhang, Bo Sun, Cheng Alsanoosi, Ali M. Aibout, Abdellah Horsewill, Anthony J. |
| author_facet | Zhang, Bo Sun, Cheng Alsanoosi, Ali M. Aibout, Abdellah Horsewill, Anthony J. |
| author_sort | Zhang, Bo |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | Field-cycling NMR in the solid state at low temperature (4.2 K) has been employed to measure the tunneling spectra of methyl (CH3) rotors in phenylacetone and toluene. The phenomenon of tunnel resonance reveals anomalies in 1H magnetization from which the following tunnel frequencies have been determined: phenylacetone, vt = 6.58+-0.08 MHz ; toluene, vt = 6.45+-0.06 GHz and vt = 7.07+-0.06 GHz. The tunnel frequencies in the two samples differ by three orders of magnitude, meaning different experimental approaches are required. In phenylacetone the magnetization anomalies are observed when the tunnel frequency matches one or two times the 1H Larmor frequency. In toluene, doping with free radicals enables magnetization anomalies to be observed when the tunnel frequency is equal to the electron spin Larmor frequency. Cross-polarization processes between the tunneling and Zeeman systems are proposed and form the basis of a thermodynamic model to simulate the tunnel resonance spectra. These invoke space-spin interactions to drive the changes in nuclear spin-symmetry. The tunnel resonance lineshapes are explained, showing good quantitative agreement between experiment and simulations. |
| first_indexed | 2025-11-14T18:21:24Z |
| format | Article |
| id | nottingham-3274 |
| institution | University of Nottingham Malaysia Campus |
| institution_category | Local University |
| last_indexed | 2025-11-14T18:21:24Z |
| publishDate | 2014 |
| publisher | American Institute of Physics |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-32742020-05-04T16:42:40Z https://eprints.nottingham.ac.uk/3274/ Spin-symmetry conversion in methyl rotors induced by tunnel resonance at low temperature Zhang, Bo Sun, Cheng Alsanoosi, Ali M. Aibout, Abdellah Horsewill, Anthony J. Field-cycling NMR in the solid state at low temperature (4.2 K) has been employed to measure the tunneling spectra of methyl (CH3) rotors in phenylacetone and toluene. The phenomenon of tunnel resonance reveals anomalies in 1H magnetization from which the following tunnel frequencies have been determined: phenylacetone, vt = 6.58+-0.08 MHz ; toluene, vt = 6.45+-0.06 GHz and vt = 7.07+-0.06 GHz. The tunnel frequencies in the two samples differ by three orders of magnitude, meaning different experimental approaches are required. In phenylacetone the magnetization anomalies are observed when the tunnel frequency matches one or two times the 1H Larmor frequency. In toluene, doping with free radicals enables magnetization anomalies to be observed when the tunnel frequency is equal to the electron spin Larmor frequency. Cross-polarization processes between the tunneling and Zeeman systems are proposed and form the basis of a thermodynamic model to simulate the tunnel resonance spectra. These invoke space-spin interactions to drive the changes in nuclear spin-symmetry. The tunnel resonance lineshapes are explained, showing good quantitative agreement between experiment and simulations. American Institute of Physics 2014-02-28 Article PeerReviewed Zhang, Bo, Sun, Cheng, Alsanoosi, Ali M., Aibout, Abdellah and Horsewill, Anthony J. (2014) Spin-symmetry conversion in methyl rotors induced by tunnel resonance at low temperature. Journal of Chemical Physics, 140 (8). 084302. ISSN 0021-9606 http://scitation.aip.org/content/aip/journal/jcp/140/8/10.1063/1.4865835 doi:10.1063/1.4865835 doi:10.1063/1.4865835 |
| spellingShingle | Zhang, Bo Sun, Cheng Alsanoosi, Ali M. Aibout, Abdellah Horsewill, Anthony J. Spin-symmetry conversion in methyl rotors induced by tunnel resonance at low temperature |
| title | Spin-symmetry conversion in methyl rotors induced by tunnel resonance at low temperature |
| title_full | Spin-symmetry conversion in methyl rotors induced by tunnel resonance at low temperature |
| title_fullStr | Spin-symmetry conversion in methyl rotors induced by tunnel resonance at low temperature |
| title_full_unstemmed | Spin-symmetry conversion in methyl rotors induced by tunnel resonance at low temperature |
| title_short | Spin-symmetry conversion in methyl rotors induced by tunnel resonance at low temperature |
| title_sort | spin-symmetry conversion in methyl rotors induced by tunnel resonance at low temperature |
| url | https://eprints.nottingham.ac.uk/3274/ https://eprints.nottingham.ac.uk/3274/ https://eprints.nottingham.ac.uk/3274/ |