Enhanced signal sensitivity by the use of Rapid Scan (RS) electron paramagnetic resonance (EPR), a technique that allows for much faster magnetic field scans than traditional field-swept techniques, has facilitated improved data acquisition for many types of samples. For example, irradiated fingernails for radiation dosimetry have been studied using RS-EPR, which resulted in substantial decreases in detection limits. Samarium-mediated reduction mechanisms in organic synthesis have been investigated by RS-EPR providing evidence for a radical intermediate. Spectra of organic radicals exhibiting both narrow lines and closely spaced hyperfine interactions have been recorded via RS-EPR. Well-resolved spectra can be recorded at a rate of 40 spectra/minute to gain insight into molecular changes on this timescale. RS-EPR performed at low temperatures using a closed cycle helium system and a cryostat containing a region with low electrical conductivity provides very wide (>9000 G) spectra free of passage effects near 5 K, expanding the capabilities of RS-EPR.
Recent developments in arbitrary wave form generators (AWGs) provide digital waveform synthesis at high enough frequencies to be used in EPR experiments at ca. 9 GHz (X-band). A new saturation recovery (SR) EPR spectrometer has been constructed with an AWG as the microwave source. Circuit design focuses on implementation of an X-band crossed-loop resonator with a reduced quality factor (Q) to minimize dead time due to resonator ring down processes. Increased accuracy of the AWG instrument relative to conventional sources has made nitroxide spin-lattice relaxation time measurements possible via SR-EPR with S/N high enough to permit separation of electron and nuclear spin-lattice relaxation contributions. These results enabled more accurate estimation of the saturation factor in dynamic nuclear polarization (DNP) experiments.
","abstract_html":"<p>Enhanced signal sensitivity by the use of Rapid Scan (RS) electron paramagnetic resonance (EPR), a technique that allows for much faster magnetic field scans than traditional field-swept techniques, has facilitated improved data acquisition for many types of samples. For example, irradiated fingernails for radiation dosimetry have been studied using RS-EPR, which resulted in substantial decreases in detection limits. Samarium-mediated reduction mechanisms in organic synthesis have been investigated by RS-EPR providing evidence for a radical intermediate. Spectra of organic radicals exhibiting both narrow lines and closely spaced hyperfine interactions have been recorded via RS-EPR. Well-resolved spectra can be recorded at a rate of 40 spectra/minute to gain insight into molecular changes on this timescale. RS-EPR performed at low temperatures using a closed cycle helium system and a cryostat containing a region with low electrical conductivity provides very wide (>9000 G) spectra free of passage effects near 5 K, expanding the capabilities of RS-EPR.</p> <p>Recent developments in arbitrary wave form generators (AWGs) provide digital waveform synthesis at high enough frequencies to be used in EPR experiments at ca. 9 GHz (X-band). A new saturation recovery (SR) EPR spectrometer has been constructed with an AWG as the microwave source. Circuit design focuses on implementation of an X-band crossed-loop resonator with a reduced quality factor (Q) to minimize dead time due to resonator ring down processes. Increased accuracy of the AWG instrument relative to conventional sources has made nitroxide spin-lattice relaxation time measurements possible via SR-EPR with S/N high enough to permit separation of electron and nuclear spin-lattice relaxation contributions. These results enabled more accurate estimation of the saturation factor in dynamic nuclear polarization (DNP) experiments.</p>","abstract_has_math":false,"creators":["McPeak, Joseph E."],"institution":null,"degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":null,"degree_department":null,"school":null,"contributors":["Gareth R. Eaton","Sandra S. Eaton","Bryan J. Cowen","Alex Huffman","Brian J. Majestic","Anneliese Andrews"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2020,"date_issued":"2020-01-01T08:00:00Z","date_published":"2020-01-01T08:00:00Z","updated_at":"2026-07-24T02:02:19Z","subjects":["Electron paramagnetic resonance","Instrumentation","Magnetic resonance","Physical chemistry","Rapid scan","Saturation recovery","Chemistry","Electrical and Computer Engineering","Other Chemistry"],"languages":["en"],"rights":["Copyright is held by the author. User is responsible for all copyright compliance.
"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://digitalcommons.du.edu/etd/1808","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Gareth R. Eaton","Sandra S. Eaton","Bryan J. Cowen","Alex Huffman","Brian J. Majestic","Anneliese Andrews"]},{"key":"dc:creator","label":"Author","values":["McPeak, Joseph E."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2021-02-25T08:00:00Z"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Electron paramagnetic resonance","Instrumentation","Magnetic resonance","Physical chemistry","Rapid scan","Saturation recovery","Chemistry","Electrical and Computer Engineering","Other Chemistry"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright is held by the author. User is responsible for all copyright compliance.
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Recent developments in arbitrary wave form generators (AWGs) provide digital waveform synthesis at high enough frequencies to be used in EPR experiments at ca. 9 GHz (X-band). A new saturation recovery (SR) EPR spectrometer has been constructed with an AWG as the microwave source. Circuit design focuses on implementation of an X-band crossed-loop resonator with a reduced quality factor (Q) to minimize dead time due to resonator ring down processes. Increased accuracy of the AWG instrument relative to conventional sources has made nitroxide spin-lattice relaxation time measurements possible via SR-EPR with S/N high enough to permit separation of electron and nuclear spin-lattice relaxation contributions. These results enabled more accurate estimation of the saturation factor in dynamic nuclear polarization (DNP) experiments.
"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Instrument and Application Development in Saturation Recovery and Rapid Scan Electron Paramagnetic Resonance"]}]}],"canonical_facts":{"dc:contributor":["Gareth R. Eaton","Sandra S. Eaton","Bryan J. Cowen","Alex Huffman","Brian J. Majestic","Anneliese Andrews"],"dc:creator":["McPeak, Joseph E."],"dc:date.available":["2021-02-25T08:00:00Z"],"dc:description.abstract":["Enhanced signal sensitivity by the use of Rapid Scan (RS) electron paramagnetic resonance (EPR), a technique that allows for much faster magnetic field scans than traditional field-swept techniques, has facilitated improved data acquisition for many types of samples. For example, irradiated fingernails for radiation dosimetry have been studied using RS-EPR, which resulted in substantial decreases in detection limits. Samarium-mediated reduction mechanisms in organic synthesis have been investigated by RS-EPR providing evidence for a radical intermediate. Spectra of organic radicals exhibiting both narrow lines and closely spaced hyperfine interactions have been recorded via RS-EPR. Well-resolved spectra can be recorded at a rate of 40 spectra/minute to gain insight into molecular changes on this timescale. RS-EPR performed at low temperatures using a closed cycle helium system and a cryostat containing a region with low electrical conductivity provides very wide (>9000 G) spectra free of passage effects near 5 K, expanding the capabilities of RS-EPR.
Recent developments in arbitrary wave form generators (AWGs) provide digital waveform synthesis at high enough frequencies to be used in EPR experiments at ca. 9 GHz (X-band). A new saturation recovery (SR) EPR spectrometer has been constructed with an AWG as the microwave source. Circuit design focuses on implementation of an X-band crossed-loop resonator with a reduced quality factor (Q) to minimize dead time due to resonator ring down processes. Increased accuracy of the AWG instrument relative to conventional sources has made nitroxide spin-lattice relaxation time measurements possible via SR-EPR with S/N high enough to permit separation of electron and nuclear spin-lattice relaxation contributions. These results enabled more accurate estimation of the saturation factor in dynamic nuclear polarization (DNP) experiments.
"],"dc:format":["application/pdf"],"dc:identifier":["https://digitalcommons.du.edu/etd/1808"],"dc:language":["en"],"dc:rights":["Copyright is held by the author. User is responsible for all copyright compliance.
"],"dc:subject":["Electron paramagnetic resonance","Instrumentation","Magnetic resonance","Physical chemistry","Rapid scan","Saturation recovery","Chemistry","Electrical and Computer Engineering","Other Chemistry"],"dc:title":["Instrument and Application Development in Saturation Recovery and Rapid Scan Electron Paramagnetic Resonance"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."]},"updated_at":"2026-07-24T02:02:19Z"}