Development of Dynamic Nuclear Polarization for Single-sided Nuclear Magnetic Resonance

Abstract

Nuclear magnetic resonance (NMR) is a tool used to determine molecular structure and chemical dynamics within a magnetic field. This magnetic field creates different energy levels that nuclear spins can occupy. The difference in the number of spins at each energy level determines the amount of polarization, which is proportional to the detected signal. Typically, NMR instruments are expensive, require regular upkeep, restrict sample sizes to small tubes, and give low measurement signal. Single-sided NMR combats some limitations by allowing for larger sample sizes, at the expense of a larger magnetic field gradient which lowers measurement resolution. We aim to circumvent limitations by applying dynamic nuclear polarization (DNP) techniques to single-sided NMR. DNP transfers the polarization from unpaired electrons to hydrogen nuclei, increasing the detected signal and sensitivity. DNP is dependent on factors related to microwave power, radical concentration, and inherent molecular characteristics. This work demonstrates successful construction of a DNP system that maintains the open geometry of single-sided NMR using alternative hardware to excite electron spins. Various experiments reveal a large dependency on power to adequately hyperpolarize samples, leading to further developments in probing thin, interfacial regions within a large field gradient. Future work involves optimizing the DNP system in order to investigate material and biological applications using single-sided NMR.ChemistryBachelors of Science (BS