Time domain DNP at 1.2 T

[Display omitted] •NOVEL experiments are performed at 1.2 T.•Ramped-amplitude NOVEL is superior to constant amplitude NOVEL.•The SSE provides the largest signal enhancements at this field.•Interaction of the time dependent microwave field and the high-Q cavity modifies the field profiles. We present...

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Bibliographic Details
Published in:Journal of magnetic resonance (1997) 2021-08, Vol.329, p.107012-107012, Article 107012
Main Authors: Can, T.V., Tan, K.O., Yang, C., Weber, R.T., Griffin, R.G.
Format: Article
Language:English
Subjects:
Dynamic nuclear polarization
Electrons
Integrated solid effect
Magnetic Resonance Spectroscopy
Microwaves
NOVEL
Ramped amplitude NOVEL
Stretched solid effect
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Summary:[Display omitted] •NOVEL experiments are performed at 1.2 T.•Ramped-amplitude NOVEL is superior to constant amplitude NOVEL.•The SSE provides the largest signal enhancements at this field.•Interaction of the time dependent microwave field and the high-Q cavity modifies the field profiles. We present the results of an experimental pulsed DNP study at 1.2 T (33.5 GHz/51 MHz electron and 1H Larmor frequencies, respectively). The results include a comparison of constant-amplitude NOVEL (CA-NOVEL), ramped-amplitude NOVEL (RA-NOVEL) and the frequency-swept integrated solid effect (FS-ISE) experiments all of which were performed at the NOVEL matching condition, ω1S=ω0I, where ω1S is the electron Rabi frequency andω0I the proton Larmor frequency. To the best of our knowledge, this is the first pulsed DNP study carried out at field higher than X-band (0.35 T) using the NOVEL condition. A combination of high microwave power (∼150 W) and a microwave cavity with a high Q (∼500) allowed us to satisfy the NOVEL matching condition. We also observed stretched solid effect (S2E) contributions in the Zeeman field profiles when chirped pulses are applied. Furthermore, the high quality factor of the cavity limits the concentration of the radical to ∼5 mM and generates a hysteresis in the FS-ISE experiments. Nevertheless, we observe very high DNP enhancements that are comparable to the results at X-band. These promising outcomes suggest the importance of further studies at even higher fields that delineate the instrumentation and methods required for time domain DNP.
ISSN:1090-7807
1096-0856
DOI:10.1016/j.jmr.2021.107012