Modular, triple-resonance, transmission line DNP MAS probe for 500 MHz/330 GHz
Name
nihms-1539348.pdf
Description
Accepted version
Size
2.24 MB
Format
Adobe PDF
Checksum (MD5)
bc0409d5d530144266949e134120e7fe
Author(s)
Reese, Marcel
George, Christy
Yang, Chen
Jawla, Sudheer
Grün, J Tassilo
Schwalbe, Harald
Redfield, Christina
Temkin, Richard J
Griffin, Robert G
Date Issued
2019
Journal
Journal of Magnetic Resonance
Publisher
Elsevier BV
Citation
Reese, Marcel, George, Christy, Yang, Chen, Jawla, Sudheer, Grün, J Tassilo et al. 2019. "Modular, triple-resonance, transmission line DNP MAS probe for 500 MHz/330 GHz." Journal of Magnetic Resonance, 307.
Version
Author's final manuscript
Abstract
© 2019 Elsevier Inc. We describe the design and construction of a modular, triple-resonance, fully balanced, DNP-MAS probe based on transmission line technology and its integration into a 500 MHz/330 GHz DNP-NMR spectrometer. A novel quantitative probe design and characterization strategy is developed and employed to achieve optimal sensitivity, RF homogeneity and excellent isolation between channels. The resulting three channel HCN probe has a modular design with each individual, swappable module being equipped with connectorized, transmission line ports. This strategy permits attachment of a mating connector that facilitates accurate impedance measurements at these ports and allows characterization and adjustment (e.g. for balancing or tuning/matching) of each component individually. The RF performance of the probe is excellent; for example, the 13C channel attains a Rabi frequency of 280 kHz for a 3.2 mm rotor. In addition, a frequency tunable 330 GHz gyrotron operating at the second harmonic of the electron cyclotron frequency was developed for DNP applications. Careful alignment of the corrugated waveguide led to minimal loss of the microwave power, and an enhancement factor ε = 180 was achieved for U-13C urea in the glassy matrix at 80 K. We demonstrated the operation of the system with acquisition of multidimensional spectra of cross-linked lysozyme crystals which are insoluble in glycerol-water mixtures used for DNP and samples of RNA.
MIT Department
Massachusetts Institute of Technology. Plasma Science and Fusion Center
Massachusetts Institute of Technology. Department of Physics
Francis Bitter Magnet Laboratory (Massachusetts Institute of Technology)
Massachusetts Institute of Technology. Department of Chemistry
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Creative Commons Attribution-NonCommercial-NoDerivs License
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DOI of Published Version
https://doi.org/10.1016/J.JMR.2019.106573
