Oral Presentation 23rd International Society of Magnetic Resonance Conference 2023

Nuclear Spin Optical Rotation of Hyperpolarized 1H and 19F at Low Magnetic Field (#121)

Yue Zhu 1 , Yuheng Gao 1 , Shane Rodocker 1 , Christian Hilty 1 , Igor Savukov 2
  1. Texas A&M University, College Station, TX, United States
  2. New Mexico Consortium, Los Alamos, NM, United States

Nuclear spin optical rotation (NSOR) is a Faraday effect induced by nuclear spin magnetic moments [1]. The polarization rotation of light from the NSOR effect in principle occurs in any substance containing NMR active nuclei. Through the NSOR effect, optical signals from a specific location within a molecule can be addressed by radio frequency pulses acting on nuclear spins. The effect therefore holds promise for creating a combined optical/NMR spectroscopy with site selectivity in a molecule. NSOR may further be used for a readout of spin coherence with spatial localization by a focused optical beam, as may be required for future quantum information science applications of NMR. Despite these potential benefits, the detection of the NSOR effect in a wide variety of molecules is challenging. Under typical conditions the signal-to-noise ratio of the optical signal is lower than that of inductively detected NMR. This drawback can be alleviated by nuclear spin hyperpolarization, which increases the overall nuclear spin magnetic moment and enables the detection of NSOR even at low magnetic field. Low-field NMR in an open electromagnet facilitates the collection of the optical signal. Here, we first measure NSOR signals from single quantum coherences in spin-echo sequences using 1H and 19F containing liquids, prepolarizing nuclear spins at a high magnetic field of several Tesla, and circulating the sample into a low-field NMR spectrometer [2]. We then demonstrate the measurement of the same type of signal originating from molecules hyperpolarized by dissolution dynamic nuclear polarization (D-DNP). D-DNP can generate a high nuclear spin polarization for various molecules in dilute solution [3], expanding the applications of NSOR measurements. We measure NSOR constants of trifluoroethanol and dimethyl sulfoxide at 405 nm, where the latter molecule at the otherwise required high concentration would exhibit prohibitive optical absorption [4]. Because of the hyperpolarization, the DNP-NSOR signal can be measured in a single scan, or in a small number of scans. Finally, we discuss the use of in-situ hyperpolarization methods such as para-hydrogen polarization and Overhauser effect DNP, which can produce nuclear spin polarization under suitable low-field conditions without a requirement for moving the sample.

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  2. Y. Zhu, Y. Gao, S. Rodocker, I. Savukov and C. Hilty, J. Phys. Chem. Lett., 2018, 9, 3323–3327.
  3. J. H. Ardenkjaer-Larsen, B. Fridlund, A. Gram, G. Hansson, L. Hansson, M. H. Lerche, R. Servin, M. Thaning and K. Golman, Proc. Natl. Acad. Sci., 2003, 100, 10158–10163.
  4. Y. Zhu, C. Hilty and I. Savukov, Angew. Chem. Int. Ed., 2021, 60, 8823–8826.