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Title: Multi Electron Spin Cluster Enabled Dynamic Nuclear Polarization with Sulfonated BDPA
Dynamic nuclear polarization (DNP) can amplify the solid-state nuclear magnetic resonance (NMR) signal by several orders of magnitude. The mechanism of DNP utilizing α,γ- Bisdiphenylene-β-phenylallyl (BDPA) variants as Polarizing Agents (PA) has been the subject of lively discussions on account of their remarkable DNP efficiency with low demand for microwave power. We propose that electron spin clustering of SA-BDPA is responsible for its DNP performance, as revealed by the temperature-dependent shape of the central DNP profile and strong electron-electron (e-e) crosstalk seen by Electron Double Resonance. We demonstrate that a multi-electron spin cluster can be modeled with three coupled spins, where electron J (exchange) coupling between one of the e-e pairs matching the NMR Larmor frequency induces the experimentally observed absorptive central DNP profile, and the electron T1e modulated by temperature and magic angle spinning alters the shape between an absorptive and dispersive feature. Understanding the microscopic origin is key to designing new PAs to harness the microwave power-efficient DNP effect observed with BDPA variants.  more » « less
Award ID(s):
2411584
PAR ID:
10534417
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
Journal of Physical Chemistry Letters
Date Published:
Journal Name:
The Journal of Physical Chemistry Letters
Volume:
14
Issue:
51
ISSN:
1948-7185
Page Range / eLocation ID:
11640 to 11650
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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