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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.
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This content will become publicly available on November 1, 2026
High-speed, high-memory NMR spectrometer and hyperpolarizer
We report on the development of a novel nuclear magnetic resonance (NMR) spectrometer, incorporating a high-speed, commercially available arbitrary waveform transceiver (AWT) – Tabor Proteus P9484M. The spectrometer is optimized for integrated electron-nuclear spin control and dynamic nuclear polarization (DNP) and leverages the AWT’s rapid sampling rate (9 Gs/s), significant memory capacity (16 GB), and efficient data transfer capabilities (6 Gs/s). These features enable effective NMR transmit–receive operations and electron control for DNP. In particular, the high sampling rates permit NMR pulse synthesis and signal reception directly at the Larmor frequency up to ∼2.7 GHz. This can yield NMR signal-to-noise ratio (SNR) improvements by obviating the need for signal heterodyning. Additionally, the spectrometer features on-board, phase-sensitive detection, enabled by numerically controlled oscillators (NCO); and windowed acquisition can be carried out over extended periods and across millions of pulses, enabling the interrogation of nuclear spin dynamics directly in the rotating frame. The device’s architecture opens up new avenues for NMR pulse control and DNP, including closed-loop feedback control, electron decoupling, 3D spin tracking, and potential applications in quantum sensing.
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- Award ID(s):
- 2320520
- PAR ID:
- 10634756
- Publisher / Repository:
- ScienceDirect
- Date Published:
- Journal Name:
- Journal of Magnetic Resonance
- Volume:
- 380
- Issue:
- C
- ISSN:
- 1090-7807
- Page Range / eLocation ID:
- 107952
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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