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dc.contributor.advisorRobert G. Griffin.en_US
dc.contributor.authorMarkhasin, Evgenyen_US
dc.contributor.otherMassachusetts Institute of Technology. Department of Chemistry.en_US
dc.date.accessioned2014-05-23T19:34:41Z
dc.date.available2014-05-23T19:34:41Z
dc.date.copyright2013en_US
dc.date.issued2014en_US
dc.identifier.urihttp://hdl.handle.net/1721.1/87469
dc.descriptionThesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, February 2014.en_US
dc.descriptionCataloged from PDF version of thesis. "February 2014."en_US
dc.descriptionIncludes bibliographical references.en_US
dc.description.abstractSolid State Nuclear Magnetic Resonance (ssNMR) spectroscopy has blossomed over the last two decades. As ssNMR is progressively applied to more challenging systems, the sensitivity remains one of its major limiting factors. Gyrotron based high-field dynamic nuclear polarization (DNP) permits increasing the sensitivity of ssNMR by 1-2 orders magnitude, significantly extending the reach of ssNMR. Successful application of ssNMR/DNP at 5T and 9.4T stimulated interest to extending this technique to higher fields and new applications. Here, the progress toward this goal is presented. It has involved completion of the world highest field magic angle spinning (MAS) DNP spectrometer and a probe for 16.4T, initial DNP experiments on ¹⁷ O nuclei, variable temperature studies of a model tripeptide, and a systematic analysis of a novel approach to high efficiency RF circuit design. The extension of DNP-NMR to 16.4T has required the development of probe technology, cryogenics, gyrotrons, and microwave transmission lines. A novel DNP probe and cryogenic instrumentation permit extended operation at 85-90K and 10kHz MAS. Initial enhancements [epsilon]=-40 and further optimization of experimental conditions is underway. ¹⁷ O detected DNP-NMR of a water/glycerol glass at 5T enabled an 80-fold enhancement of signal intensities at 82K permitting ¹⁷ O- ¹H distance measurements and heteronuclear correlation experiments. Variable temperature MAS NMR studies of a model tripeptide APG in combination with cryogenic calorimetry and XRD revealed a first-order phase transition and severe attenuation of the cross polarization MAS signal in a wide temperature range due to interference between decoupling and 3-fold hopping of the Ala-CH₃ and Ala-NH₃+ groups. A new, efficient strategy for designing balanced transmission line RF circuits for MAS NMR probes based on back propagation of a common impedance node (BPCIN) is presented. In this approach, the impedance node is the sole means of achieving mutual RF isolation and balance in all channels. BPCIN is illustrated using a custom double resonance MAS probe operating at 11.7T.en_US
dc.description.statementofresponsibilityby Evgeny Markhasin.en_US
dc.format.extent149 pagesen_US
dc.language.isoengen_US
dc.publisherMassachusetts Institute of Technologyen_US
dc.rightsM.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.en_US
dc.rights.urihttp://dspace.mit.edu/handle/1721.1/7582en_US
dc.subjectChemistry.en_US
dc.titleHigh field DNP and cryogenic MAS NMR : novel instrumentation and applicationsen_US
dc.title.alternativeHigh field dynamic nuclear polarization and cryogenic magic angle spinning Nuclear Magnetic Resonanceen_US
dc.typeThesisen_US
dc.description.degreePh. D.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Chemistry
dc.identifier.oclc879662127en_US


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