Abstract: The general theoretical approach for description of different types of spin hyperpolarization have been re-formulated in terms of level crossings (LC) and level anti-crossings (LAC) of interacting spin states[1]. To explore fully the high potential of the unified approach by addressing to different types of LACs through magnetic field variation, a fully automatic low-cost field cycling add-on to cover the ultra-wide magnetic field range from 10 nT to 19.4 T was built in Novosibirsk[2]. Our shuttling device is compact and compatible with any type of commercial high resolution NMR spectrometer. It allows high-throughput of para-hydrogen induced nuclear spin hyperpolarization (PHIP) and SABRE, as well as proton and heteronuclear photo-CIDNP and photo-SSABRE. We proved that the most efficient polarization transfer occurs at LACs and such transfer is of coherent nature. Based on magnetic field dependence, a facile experimental protocols were proposed for highly efficient hyperpolarization of 13C, 15N, 19F, 31P, 77Se nuclei via adiabatic magnetic field modulation at LACs. Proposed approach makes it possible to improve the efficiency of hyperpolarization processes at zero and ultralow magnetic field (ZULF) [3], as well as at weak and strong magnetic fields via application of shaped pulses of oscillating magnetic fields. For nuclear spins of molecular para-hydrogen interacting with catalytic complex we explored the para–ortho conversion rate dependence on magnetic field and found that energy level anti-crossing boosts conversion of para-hydrogen. In spin chemistry, magnetic interactions of electrons and nuclei spin are encoded in field dependence of CIDNP that is modulated by nuclear relaxation dispersion. Theirs combined study over ultra-wide magnetic field range allows to disentangle contributions of the different mechanisms to singlet-triplet conversion and to reveal polarization transfer among nuclei. For set of well-designed of donor-acceptor dyads and flavin-adenine-dinucleotide (FAD) [4] studied by 13C and 1H field-dependent and time-resolved photo-CIDNP and supported by modern theoretical calculations we explained LACs in magnetic field dependence and determined the sign and the values of electronic exchange interaction in transient short-lived biradicals. Funding: This work was supported by the Russian Science Foundation (grant number #23-73-10103)

Cite: Fishman N. , Geniman M. , Kiryutin A. , Kozinenko V. , Lukzen N. , Morozova O. , Markelov D. , Snadin A. , Zhukov I. , Yurkovskaya A.
Low-cost, high-throughput nuclear spin hyperpolarization and high resolution NMR relaxometry over ultra-wide magnetic field range
In compilation Book of abstracts of Spin Chemistry Meeting. 2024.

Dates:

Submitted:	Jun 30, 2024
Published online:	Oct 1, 2024

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