A 140 GHz pulsed EPR/212 MHz NMR spectrometer for DNP studies
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Griffin_A 140ghz pulsed.pdf
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Author(s)
Smith, Albert A.
Bryant, Jeffrey A.
DeRocher, Ronald
Woskov, Paul P.
Corzilius, Bjorn
Griffin, Robert Guy
Temkin, Richard J
Date Issued
July 2012
Journal
Journal of Magnetic Resonance
Publisher
Elsevier
Citation
Smith, Albert A., Björn Corzilius, Jeffrey A. Bryant, Ronald DeRocher, Paul P. Woskov, Richard J. Temkin, and Robert G. Griffin. “A 140GHz Pulsed EPR/212MHz NMR Spectrometer for DNP Studies.” Journal of Magnetic Resonance 223 (October 2012): 170–179.
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Author's final manuscript
Abstract
We described a versatile spectrometer designed for the study of dynamic nuclear polarization (DNP) at low temperatures and high fields. The instrument functions both as an NMR spectrometer operating at 212 MHz ([superscript 1]H frequency) with DNP capabilities, and as a pulsed-EPR operating at 140 GHz. A coiled TE[subscript 011] resonator acts as both an NMR coil and microwave resonator, and a double balanced ([superscript 1]H, [superscript 13]C) radio frequency circuit greatly stabilizes the NMR performance. A new 140 GHz microwave bridge has also been developed, which utilizes a four-phase network and ELDOR channel at 8.75 GHz, that is then multiplied and mixed to obtain 140 GHz microwave pulses with an output power of 120 mW. Nutation frequencies obtained are as follows: 6 MHz on S = 1/2 electron spins, 100 kHz on [superscript 1]H, and 50 kHz on [superscript 13]C. We demonstrate basic EPR, ELDOR, ENDOR, and DNP experiments here. Our solid effect DNP results demonstrate an enhancement of 144 and sensitivity gain of 310 using OX063 trityl at 80 K and an enhancement of 157 and maximum sensitivity gain of 234 using Gd-DOTA at 20 K, which is significantly better performance than previously reported at high fields (⩾3 T).
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Plasma Science and Fusion Center
Francis Bitter Magnet Laboratory (Massachusetts Institute of Technology)
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DOI of Published Version
https://doi.org/10.1016/j.jmr.2012.07.008
