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Dynamic nuclear polarization at 9T using a novel 250GHz gyrotron microwave source
V S Bajaj1, C T Farrar, M K Hornstein
1Francis Bitter Magnet Laboratory, Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Room NW 14-3220, Cambridge, MA 02139, USA.
Journal of Magnetic Resonance (San Diego, Calif. : 1997)
|March 5, 2003
Summary
Dynamic nuclear polarization (DNP) significantly enhances nuclear spin polarization in solids using a thermal mixing mechanism. These high-frequency DNP experiments demonstrate substantial signal gains at elevated magnetic fields.
Area of Science:
- Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy
- Dynamic Nuclear Polarization (DNP)
- Biophysics
Background:
- Nuclear spin polarization is crucial for NMR sensitivity.
- Dynamic Nuclear Polarization (DNP) enhances polarization via electron-spin interactions.
- Previous DNP studies were limited by magnetic field strength and frequency.
Purpose of the Study:
- To report enhancements of nuclear spin polarization using DNP at high magnetic fields (9T).
- To demonstrate the efficacy of the thermal mixing DNP mechanism at high frequencies (250 GHz).
- To validate DNP's applicability in static and spinning solids for various NMR experiments.
Main Methods:
- Utilized dynamic nuclear polarization (DNP) with a thermal mixing mechanism.
- Employed 4-amino-TEMPO as the paramagnetic dopant.
- Conducted experiments on static and magic angle spinning (MAS) solids at 9T and 20K.
Main Results:
- Achieved 1H enhancements up to 170±50 in 1-13C-glycine.
- Observed significant 15N enhancements in pf1-bacteriophage samples.
- Obtained enhancements of approximately 17 in 2D 13C-13C correlation spectra of U-13C, 15N-proline during MAS.
Conclusions:
- High-frequency DNP experiments at 9T yield substantial signal enhancements.
- The thermal mixing DNP mechanism is effective even at elevated magnetic fields.
- DNP is a stable and quantitative technique suitable for advanced NMR experiments.