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Frequency‐Swept Integrated Solid Effect
Author(s) -
Can Thach V.,
Weber Ralph T.,
Walish Joseph J.,
Swager Timothy M.,
Griffin Robert G.
Publication year - 2017
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201700032
Subject(s) - polarization (electrochemistry) , microwave , frequency domain , physics , computational physics , materials science , nuclear magnetic resonance , chemistry , computer science , quantum mechanics , computer vision
The efficiency of continuous wave dynamic nuclear polarization (DNP) experiments decreases at the high magnetic fields used in contemporary high‐resolution NMR applications. To recover the expected signal enhancements from DNP, we explored time domain experiments such as NOVEL which matches the electron Rabi frequency to the nuclear Larmor frequency to mediate polarization transfer. However, satisfying this matching condition at high frequencies is technically demanding. As an alternative we report here frequency‐swept integrated solid effect (FS‐ISE) experiments that allow low power sweeps of the exciting microwave frequencies to constructively integrate the negative and positive polarizations of the solid effect, thereby producing a polarization efficiency comparable to (±10 % difference) NOVEL. Finally, the microwave frequency modulation results in field profiles that exhibit new features that we coin the “stretched” solid effect.