Solid effect in magic angle spinning dynamic nuclear polarization
For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic field DNP experiments because SE enhancements display an ω[−2 over 0] field de...
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| Format: | Article |
| Language: | en_US |
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American Institute of Physics (AIP)
2013
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| Online Access: | http://hdl.handle.net/1721.1/82077 https://orcid.org/0000-0003-1589-832X |
| _version_ | 1826212343121444864 |
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| author | Smith, Albert A. Corzilius, Bjorn Griffin, Robert Guy |
| author2 | Massachusetts Institute of Technology. Department of Chemistry |
| author_facet | Massachusetts Institute of Technology. Department of Chemistry Smith, Albert A. Corzilius, Bjorn Griffin, Robert Guy |
| author_sort | Smith, Albert A. |
| collection | MIT |
| description | For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic field DNP experiments because SE enhancements display an ω[−2 over 0] field dependence. In particular, for nominally forbidden zero and double quantum SE transitions to be partially allowed, it is necessary for mixing of adjacent nuclear spin states to occur, and this leads to the observed field dependence. However, recently we have improved our instrumentation and report here an enhancement of ɛ = 91 obtained with the organic radical trityl (OX063) in magic angle spinning experiments performed at 5 T and 80 K. This is a factor of 6-7 higher than previous values in the literature under similar conditions. Because the solid effect depends strongly on the microwave field strength, we attribute this large enhancement to larger microwave field strengths inside the sample volume, achieved with more efficient coupling of the gyrotron to the sample chamber. In addition, we develop a theoretical model to explain the dependence of the buildup rate of enhanced nuclear polarization and the steady-state enhancement on the microwave power. Buildup times and enhancements were measured as a function of [superscript 1]H concentration for both trityl and Gd-DOTA. Comparison of the results indicates that for trityl the initial polarization step is the slower, rate-determining step. However, for Gd-DOTA the spread of nuclear polarization via homonuclear [superscript 1]H spin diffusion is rate-limiting. Finally, we discuss the applicability of the solid effect at fields > 5 T and the requirements to address the unfavorable field dependence of the solid effect. |
| first_indexed | 2024-09-23T15:20:12Z |
| format | Article |
| id | mit-1721.1/82077 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T15:20:12Z |
| publishDate | 2013 |
| publisher | American Institute of Physics (AIP) |
| record_format | dspace |
| spelling | mit-1721.1/820772022-10-02T02:14:22Z Solid effect in magic angle spinning dynamic nuclear polarization Smith, Albert A. Corzilius, Bjorn Griffin, Robert Guy Massachusetts Institute of Technology. Department of Chemistry Francis Bitter Magnet Laboratory (Massachusetts Institute of Technology) Corzilius, Bjorn Smith, Albert A. Griffin, Robert Guy For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic field DNP experiments because SE enhancements display an ω[−2 over 0] field dependence. In particular, for nominally forbidden zero and double quantum SE transitions to be partially allowed, it is necessary for mixing of adjacent nuclear spin states to occur, and this leads to the observed field dependence. However, recently we have improved our instrumentation and report here an enhancement of ɛ = 91 obtained with the organic radical trityl (OX063) in magic angle spinning experiments performed at 5 T and 80 K. This is a factor of 6-7 higher than previous values in the literature under similar conditions. Because the solid effect depends strongly on the microwave field strength, we attribute this large enhancement to larger microwave field strengths inside the sample volume, achieved with more efficient coupling of the gyrotron to the sample chamber. In addition, we develop a theoretical model to explain the dependence of the buildup rate of enhanced nuclear polarization and the steady-state enhancement on the microwave power. Buildup times and enhancements were measured as a function of [superscript 1]H concentration for both trityl and Gd-DOTA. Comparison of the results indicates that for trityl the initial polarization step is the slower, rate-determining step. However, for Gd-DOTA the spread of nuclear polarization via homonuclear [superscript 1]H spin diffusion is rate-limiting. Finally, we discuss the applicability of the solid effect at fields > 5 T and the requirements to address the unfavorable field dependence of the solid effect. National Institutes of Health (U.S.) (Grant EB002804) National Institutes of Health (U.S.) (Grant EB002026) 2013-11-12T13:57:44Z 2013-11-12T13:57:44Z 2012-08 2012-04 Article http://purl.org/eprint/type/JournalArticle 00219606 1089-7690 http://hdl.handle.net/1721.1/82077 Corzilius, Bjorn, Albert A. Smith, and Robert G. Griffin. “Solid effect in magic angle spinning dynamic nuclear polarization.” The Journal of Chemical Physics 137, no. 5 (2012): 054201. © 2012 American Institute of Physics https://orcid.org/0000-0003-1589-832X en_US http://dx.doi.org/10.1063/1.4738761 The Journal of Chemical Physics Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Institute of Physics (AIP) MIT web domain |
| spellingShingle | Smith, Albert A. Corzilius, Bjorn Griffin, Robert Guy Solid effect in magic angle spinning dynamic nuclear polarization |
| title | Solid effect in magic angle spinning dynamic nuclear polarization |
| title_full | Solid effect in magic angle spinning dynamic nuclear polarization |
| title_fullStr | Solid effect in magic angle spinning dynamic nuclear polarization |
| title_full_unstemmed | Solid effect in magic angle spinning dynamic nuclear polarization |
| title_short | Solid effect in magic angle spinning dynamic nuclear polarization |
| title_sort | solid effect in magic angle spinning dynamic nuclear polarization |
| url | http://hdl.handle.net/1721.1/82077 https://orcid.org/0000-0003-1589-832X |
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