Dynamic Nuclear Polarization Using Electron Spin Cluster

Raj K. Chaklashiya, Asif Equbal, Andrey Shernyukov, Yuanxin Li, Karen Tsay, Quentin Stern, Victor Tormyshev, Elena Bagryanskaya, Songi Han

Research output: Contribution to journalArticlepeer-review


Dynamic nuclear polarization (DNP) utilizing narrow-line electron spin clusters (ESCs) to achieve nuclear spin resonance matching (ESC-DNP) by microwave irradiation is a promising way to achieve NMR signal enhancements with a wide design scope requiring low microwave power at high magnetic field. Here we present the design for a trityl-based tetra-radical (TetraTrityl) to achieve DNP for 1H NMR at 7 T, supported by experimental data and quantum mechanical simulations. A slow-relaxing (T1e ≈ 1 ms) 4-ESC is found to require at least two electron spin pairs at <8 Å e-e spin distance to yield 1H ESC-DNP enhancement, while squeezing the rest of the e-e spin distances to <12 Å results in optimal 1H ESC-DNP enhancements. Fast-relaxing ESCs (T1e ≈ 10 μs) are found to require a weakly coupled narrow-line radical (sensitizer) to extract polarization from the ESC. These results provide design principles for achieving a power-efficient DNP at high field via ESC-DNP.

Original languageEnglish (US)
Pages (from-to)5366-5375
Number of pages10
JournalJournal of Physical Chemistry Letters
Issue number20
StatePublished - May 23 2024

ASJC Scopus subject areas

  • General Materials Science
  • Physical and Theoretical Chemistry


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