Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 3 of 3
Full-Text Articles in Physical Sciences and Mathematics
Magic Angle Spinning Spheres And Improved Microwave Coupling For Magnetic Resonance, Pin-Hui Chen
Magic Angle Spinning Spheres And Improved Microwave Coupling For Magnetic Resonance, Pin-Hui Chen
Arts & Sciences Electronic Theses and Dissertations
Nuclear magnetic resonance (NMR) is a nondestructive technique used to characterize molecular structure and dynamics with atomic resolution. In solid-state NMR, magic angle spinning (MAS) is commonly implemented to improve spectral resolution by partially averaging anisotropic interactions. To further improve NMR sensitivity, dynamic nuclear polarization (DNP) is utilized to transfer the polarization from electron spins to nuclei of interest using microwaves. Advanced MAS DNP NMR instrumentation, such as spherical rotors for stable and fast spinning, dielectric lenses to effectively couple the microwaves into the sample, and the separation of receiving and transmitting circuits to decrease measurement noise, are developed to …
Electron Decoupling With Chirped Microwave Pulses For Magic Angle Spinning Dynamic Nuclear Polarization Nuclear Magnetic Resonance Spectroscopy, Edward Paul Saliba
Electron Decoupling With Chirped Microwave Pulses For Magic Angle Spinning Dynamic Nuclear Polarization Nuclear Magnetic Resonance Spectroscopy, Edward Paul Saliba
Arts & Sciences Electronic Theses and Dissertations
Dynamic nuclear polarization (DNP) is a method of generating hyperpolarization of nuclear spins for nuclear magnetic resonance (NMR) spectroscopy. Coherent, time domain techniques make the possibility of DNP directly to spins of interest at room temperature and higher feasible in magic angle spinning (MAS) NMR, allowing for optimal experimental repetition times to be limited by the T_1 of the electron, rather than a much longer T_1DNP, with excellent resolution. The strong hyperfine couplings that make such direct DNP transfers possible, however, can lead to short nuclear relaxation times that result in broadening of nuclear resonances and reduce sensitivity. This dissertation …
Instrumentation For Cryogenic Dynamic Nuclear Polarization And Electron Decoupling In Rotating Solids, Faith Joellen Scott
Instrumentation For Cryogenic Dynamic Nuclear Polarization And Electron Decoupling In Rotating Solids, Faith Joellen Scott
Arts & Sciences Electronic Theses and Dissertations
Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) using the higher polarization of electron radical spins compared to nuclear spins. The addition of electron radicals for DNP to the sample can cause hyperfine broadening, which decreases the resolution of the NMR resonances due to hyperfine interactions between electron and nuclear spins. Electron decoupling has been shown to attenuate the effects of hyperfine coupling in rotating solids. Magic angle spinning (MAS) DNP with electron decoupling requires a high electron Rabi frequency provided by a high-power microwave source such as a frequency-agile gyrotron. This dissertation describes the development …