{"id":{"repo_id":"mit","oai_identifier":"oai:dspace.mit.edu:1721.1/157830"},"canonical_url":"https://search.dev.ndltd.org/etd/mit/oai:dspace.mit.edu:1721.1/157830","repository":{"repo_id":"mit","name":"MIT","base_url":"https://dspace.mit.edu/oai/request"},"display":{"title":"High field dynamic nuclear polarization methods: Microwave sources and mechanisms","abstract":"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.","abstract_html":"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.","abstract_has_math":false,"creators":["Mardini, Michael"],"institution":"Massachusetts Institute of Technology","degree_name":"Doctoral","degree_level":null,"degree_discipline":null,"degree_department":"Massachusetts Institute of Technology. Department of Chemistry","school":null,"contributors":[],"advisors":["Griffin, Robert G."],"committee_chairs":[],"committee_members":[],"year":2024,"date_issued":"2024-02","date_published":"2024-02","updated_at":"2026-07-22T22:21:01Z","subjects":[],"languages":[],"rights":["Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)","Copyright retained by author(s)"],"rights_urls":["https://creativecommons.org/licenses/by-nc-nd/4.0/"],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/1721.1/157830","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Griffin, Robert G."]},{"key":"dc:contributor.department","label":"Department","values":["Massachusetts Institute of Technology. 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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."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph.D."]},{"key":"dc:title","label":"Title","values":["High field dynamic nuclear polarization methods: Microwave sources and mechanisms"]}]}],"canonical_facts":{"dc:contributor.advisor":["Griffin, Robert G."],"dc:contributor.department":["Massachusetts Institute of Technology. Department of Chemistry"],"dc:creator":["Mardini, Michael"],"dc:date.accessioned":["2024-12-11T15:05:01Z"],"dc:date.available":["2024-12-11T15:05:01Z"],"dc:date.issued":["2024-02"],"dc:description.abstract":["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."],"dc:description.degree":["Ph.D."],"dc:identifier.uri":["https://hdl.handle.net/1721.1/157830"],"dc:publisher":["Massachusetts Institute of Technology"],"dc:rights":["Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)","Copyright retained by author(s)"],"dc:rights.uri":["https://creativecommons.org/licenses/by-nc-nd/4.0/"],"dc:title":["High field dynamic nuclear polarization methods: Microwave sources and mechanisms"],"dc:type":["Thesis"],"thesis:degree_name":["Doctoral","Doctor of Philosophy"]},"updated_at":"2026-07-22T22:21:01Z"}