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Exploring the Limits of Overhauser Dynamic Nuclear Polarization (O-DNP) for Portable Magnetic Resonance Detection of Low γ Nuclei

Yoder, J. L. ; Magnelind, P. E. ; Espy, M. A. ; Janicke, M. T.

Applied magnetic resonance, 2018-07, Vol.49 (7), p.707-724 [Periódico revisado por pares]

Vienna: Springer Vienna

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Título:
Exploring the Limits of Overhauser Dynamic Nuclear Polarization (O-DNP) for Portable Magnetic Resonance Detection of Low γ Nuclei
Autor: Yoder, J. L. ; Magnelind, P. E. ; Espy, M. A. ; Janicke, M. T.
Assuntos: Atomic and Nuclear Physics ; Atoms and Molecules in Strong Fields ; Electron paramagnetic resonance ; Electrons ; Field strength ; Free radicals ; Gyromagnetic ratio ; INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY ; Laser Matter Interaction ; Magnetic fields ; NMR ; NMR Overhauser DNP ULF ; NMR spectroscopy ; Nuclear magnetic resonance ; Nuclei (nuclear physics) ; Organic Chemistry ; Original Paper ; Overhauser effect ; Permanent magnets ; Physical Chemistry ; Physics ; Physics and Astronomy ; Polarization ; Portability ; RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY ; Radio frequency ; Solid State Physics ; Spectrometers ; Spectroscopy/Spectrometry ; Spin exchange
É parte de: Applied magnetic resonance, 2018-07, Vol.49 (7), p.707-724
Notas: USDOE Laboratory Directed Research and Development (LDRD) Program
AC52-06NA25396
LA-UR-17-28705
Descrição: Nuclear magnetic resonance (NMR) spectroscopy in portable, permanent magnet-based spectrometers is primarily limited to nuclei with higher gyromagnetic ratio, γ , such as 1 H, 19 F, and 31 P due to the limited field strength achievable in these systems. Overhauser effect dynamic nuclear polarization (O-DNP), which transfers polarization from an unpaired electron to a nucleus by saturating an electron paramagnetic resonance transition with an oscillating radio frequency magnetic field, B 1e , can increase the polarization of low γ nuclei by hundreds or even thousands, enabling detection in a portable system. We have investigated the potential for O-DNP to enhance signals using (4-amino-2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO hereafter) as a source of unpaired electrons in a homebuilt ultra-low field (ULF) O-DNP-NMR spectrometer. We have found, in general, that larger concentrations of TEMPO are required for effective O-DNP with low γ nuclei, which has a number of important effects. Spin exchange effects cause the EPR lines to overlap and ultimately merge at high concentrations of TEMPO, fundamentally increasing the maximum possible enhancement, while the electron–electron dipolar interaction reduces both longitudinal and transverse relaxation times for the electrons, dramatically increasing the required B 1e strength. The relationship between TEMPO concentration, B 1e magnitude and O-DNP enhancement is quantified, and strategies for achieving these fields are discussed.
Editor: Vienna: Springer Vienna
Idioma: Inglês

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Exploring the Limits of Overhauser Dynamic Nuclear Polarization (O-DNP) for Portable Magnetic Resonance Detection of Low γ Nuclei

Yoder, J. L. ; Magnelind, P. E. ; Espy, M. A. ; Janicke, M. T.

Vienna: Springer Vienna

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