Mechanism of spontaneous polarization transfer in high-field SABRE experiments

Mechanism of spontaneous polarization transfer in high-field SABRE experiments Научная публикация

Журнал

Journal of Magnetic Resonance
ISSN: 1090-7807

Вых. Данные

Год: 2018, Том: 287, Страницы: 74-81 Страниц : 8 DOI: 10.1016/j.jmr.2017.12.018

Авторы

Knecht Stephan ¹ , Kiryutin Alexey S. ^2,3 , Yurkovskaya Alexandra V. ^2,3 , Ivanov Konstantin L. ^2,3

Организации

1	Dept. of Radiology, Medical Physics, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Germany
2	International Tomography Center, Siberian Branch of the Russian Academy of Science, Novosibirsk 630090, Russia
3	Novosibirsk State University, Novosibirsk, 630090, Russia

We propose an explanation of the previously reported SABRE (Signal Amplification By Reversible Exchange) effect at high magnetic fields, observed in the absence of RF-excitation and relying only on “spontaneous” polarization transfer from parahydrogen (pH2, the H2 molecule in its nuclear singlet spin state) to a SABRE substrate. We propose a detailed mechanism for spontaneous polarization transfer and show that it is comprised of three steps: (i) Generation of the anti-phase I ̂ 1 z I ̂ 2 z spin order of catalyst-bound H2; (ii) spin order conversion I ̂ 1 z I ̂ 2 z → ( I ̂ 1 z + I ̂ 2 z ) due to cross-correlated relaxation, leading to net polarization of H2; (iii) polarization transfer to the SABRE substrate, occurring due to NOE. Formation of anti-phase polarization is due to singlet-to-T0 mixing in the catalyst-bound form of H2, while cross-correlated relaxation originates from fluctuations of dipole-dipole interactions and chemical shift anisotropy. The proposed mechanism is supported by a theoretical treatment, magnetic field-dependent studies and high-field NMR measurements with both pH2 and thermally polarized H2.

Knecht S. , Kiryutin A.S. , Yurkovskaya A.V. , Ivanov K.L.
Mechanism of spontaneous polarization transfer in high-field SABRE experiments
Journal of Magnetic Resonance. 2018. V.287. P.74-81. DOI: 10.1016/j.jmr.2017.12.018

Поступила в редакцию:	8 нояб. 2017 г.
Принята к публикации:	24 дек. 2017 г.
Опубликована online:	26 дек. 2017 г.

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