High field dynamic nuclear polarization methods: Microwave sources and mechanisms
In thirty years of active development, dynamic nuclear polarization (DNP) has emerged as a forefront technique for expanding the scope of solid state nuclear magnetic resonance. For the most part, and particularly at high fields, these advances have come with continuous-wave microwave irradiation an...
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| Format: | Thesis |
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Massachusetts Institute of Technology
2024
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| Online Access: | https://hdl.handle.net/1721.1/157830 |
| _version_ | 1824457948613574656 |
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| author | Mardini, Michael |
| author2 | Griffin, Robert G. |
| author_facet | Griffin, Robert G. Mardini, Michael |
| author_sort | Mardini, Michael |
| collection | MIT |
| description | In thirty years of active development, dynamic nuclear polarization (DNP) has emerged as a forefront technique for expanding the scope of solid state nuclear magnetic resonance. For the most part, and particularly at high fields, these advances have come with continuous-wave microwave irradiation and the introduction of nitroxide-based biradicals exploiting the cross effect mechanism. In this thesis, I argue that this approach is not necessarily optimal and report progress towards arbitrary-waveform DNP, in the construction of a suitable solid-state microwave source, and the use of narrow-line monoradicals exploiting the Overhauser effect. My colleagues and I have also investigated the Overhauser mechanism through selective deuteration of radicals, leading to a relatively simple modification which yielded a significant increase in Overhauser enhancement. Finally, I detail studies of two unexplored DNP mechanisms in trityl: the three-spin solid effect and resonant mixing. With solid-state microwave sources and Overhauser radicals, DNP is now more accessible as we can achieve reasonable enhancement without the need for a gyrotron. Moreover, as amplifier and resonator technologies continue to develop, it is likely that pulsed DNP will emerge at high fields and overtake continuous-wave DNP in absolute sensitivity enhancement as well. |
| first_indexed | 2025-02-19T04:18:06Z |
| format | Thesis |
| id | mit-1721.1/157830 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2025-02-19T04:18:06Z |
| publishDate | 2024 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/1578302024-12-12T03:59:11Z High field dynamic nuclear polarization methods: Microwave sources and mechanisms Mardini, Michael Griffin, Robert G. Massachusetts Institute of Technology. Department of Chemistry In thirty years of active development, dynamic nuclear polarization (DNP) has emerged as a forefront technique for expanding the scope of solid state nuclear magnetic resonance. For the most part, and particularly at high fields, these advances have come with continuous-wave microwave irradiation and the introduction of nitroxide-based biradicals exploiting the cross effect mechanism. In this thesis, I argue that this approach is not necessarily optimal and report progress towards arbitrary-waveform DNP, in the construction of a suitable solid-state microwave source, and the use of narrow-line monoradicals exploiting the Overhauser effect. My colleagues and I have also investigated the Overhauser mechanism through selective deuteration of radicals, leading to a relatively simple modification which yielded a significant increase in Overhauser enhancement. Finally, I detail studies of two unexplored DNP mechanisms in trityl: the three-spin solid effect and resonant mixing. With solid-state microwave sources and Overhauser radicals, DNP is now more accessible as we can achieve reasonable enhancement without the need for a gyrotron. Moreover, as amplifier and resonator technologies continue to develop, it is likely that pulsed DNP will emerge at high fields and overtake continuous-wave DNP in absolute sensitivity enhancement as well. Ph.D. 2024-12-11T15:05:01Z 2024-12-11T15:05:01Z 2024-02 2024-12-09T18:07:54.312Z Thesis https://hdl.handle.net/1721.1/157830 Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) Copyright retained by author(s) https://creativecommons.org/licenses/by-nc-nd/4.0/ application/pdf Massachusetts Institute of Technology |
| spellingShingle | Mardini, Michael High field dynamic nuclear polarization methods: Microwave sources and mechanisms |
| title | High field dynamic nuclear polarization methods: Microwave sources and mechanisms |
| title_full | High field dynamic nuclear polarization methods: Microwave sources and mechanisms |
| title_fullStr | High field dynamic nuclear polarization methods: Microwave sources and mechanisms |
| title_full_unstemmed | High field dynamic nuclear polarization methods: Microwave sources and mechanisms |
| title_short | High field dynamic nuclear polarization methods: Microwave sources and mechanisms |
| title_sort | high field dynamic nuclear polarization methods microwave sources and mechanisms |
| url | https://hdl.handle.net/1721.1/157830 |
| work_keys_str_mv | AT mardinimichael highfielddynamicnuclearpolarizationmethodsmicrowavesourcesandmechanisms |