Аннотация
SABRE (Signal Amplification By Reversible Exchange) is a technique for enhancement of NMR (Nuclear Magnetic Resonance) signals, which utilises parahydrogen (pH 2, the H 2 molecule in its nuclear singlet spin state) as a source of non-thermal spin order. In SABRE experiments, pH 2 binds transiently to an organometallic complex with a to-be-polarised substrate; subsequently, spin order transfer takes place and the substrate acquires non-thermal spin polarisation resulting in strong NMR signal enhancement. In this work, we argue that the spin order of H 2 in SABRE experiments performed at high magnetic fields is not necessarily the singlet order but rather anti-phase polarisation, S1zS2z. Although SABRE exploits pH 2, i.e. the starting spin order of H 2 is supposed to be the singlet order, in solution, S−T 0 conversion becomes efficient once pH 2 binds to a complex. Such a variation of the spin order, which becomes S1zS2z, has an important consequence: NMR methods used for transferring SABRE polarisation need to be modified. Here we demonstrate that methods proposed for the initial singlet order may not work for the S1zS2z order; however, a simple modification makes them efficient again.
Язык оригинала | английский |
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Страницы (с-по) | 2762-2771 |
Число страниц | 10 |
Журнал | Molecular Physics |
Том | 117 |
Номер выпуска | 19 |
DOI | |
Состояние | Опубликовано - 2 окт. 2019 |