High Field DNP NMR probe design and application in crystalline solids

Dynamic nuclear polarization (DNP) is a valuable tool which can be used to enhance nuclear magnetic resonance (NMR) signal intensities in a variety of biological and materials science systems, by transferring polarization from unpaired electrons to nuclei. In this thesis, the mechanical design and radio frequency NMR circuit for a triple channel magic angle spinning (MAS) DNP NMR probe for operation at 5 Tesla are developed, and the construction of the probe is detailed. The probe carries out NMR in three frequency ranges, corresponding to the 1H, 1 3C, and 15N Larmor frequencies at 5 T, but can be tuned to other nuclei as well, in particular 2 H. A 1H cross effect DNP enhancement of 40 on 1 3C labeled urea, using 10 mM TOTAPOL, is reported after cross polarization to 13C. As of writing, the probe is undergoing further optimization to improve the enhancement. The dynamics and interactions of water molecules are studied in lanthanum magnesium nitrate hydrate (La 2Mg3 (NO 3 )12 24H 20) (LMN) using a variety of 2H and 170 NMR techniques. Variable temperature 2H spectra are studied to characterize water dynamics in LMN, and the 170 quadrupole interaction is studied in an attempt to resolve crystallographically distinct water sites. 170 MQMAS is performed. Gadolinium is explored as a polarizing agent for DNP enhanced NMR. LMN crystals doped with Gd are synthesized, with the goal of using the enhancement from DNP to allow further characterization of crystalline solids. Polarization transfer to 1H in LMN doped with 3% Gd through the solid effect at 5 T is observed, and an NMR enhancement of 2.5 is recorded at 85 K. Planned future work on 2H and 15N DNP in LMN, using the MAS DNP NMR probe described here, is outlined.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Physics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2013

Author dc:creator

• Wilson, Christopher Blake

Advisor dc:contributor.advisor

• Robert G. Griffin.

• Physics.

Statement dc:rights

• M.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.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/83777

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/83777