TY - JOUR

T1 - Chemically Induced Spin Hyperpolarization

T2 - Coherence Formation in Reaction Products

AU - Ivanov, Konstantin L.

AU - Yurkovskya, Alexandra V.

AU - Fishman, Natalya N.

AU - Kiryutin, Aleksey S.

AU - Sagdeev, Renad Z.

AU - Vieth, Hans Martin

N1 - Funding Information: N.N. Fishman thanks the Russian Science Foundation (Project No. 19-73-00153) for support of her work. Prof. Konstantin L. Ivanov passed away on the 5th of March, 2021 at the age 44, during the review process of this manuscript. In his early career, he made major contributions to the theory of chemical reaction kinetics in liquid phase. Later, he significantly contributed to unraveling the mechanisms of light-induced nuclear hyperpolarization in liquids and molecular crystals using the concept of level anti-crossing (LAC). In recent years, his main research efforts, both theoretical and experimental, were concentrated on spin and chemical dynamics in PHIP and SABRE methods using LAC; for this, he was awarded the Günther Laukien Prize in 2020. Hyperpolarization and LACs in fast field cycling was his final project. Publisher Copyright: © 2021, The Author(s). Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2022/5

Y1 - 2022/5

N2 - Chemically induced dynamic nuclear polarization (CIDNP) has emerged as a highly informative method to study spin-dependent radical reactions by analyzing enhanced NMR (nuclear magnetic resonance) signals of their diamagnetic reaction products. In this way, one can probe the structure of elusive radical intermediates and determine their magnetic parameters. A careful examination of experimental CIDNP data at variable magnetic fields shows that formation of hyperpolarized molecules in a coherent state is a ubiquitous though rarely discussed phenomenon. The presence of nuclear spin coherences commonly leads to subsequent polarization transfer among coupled spins in the diamagnetic products of radical recombination reaction that must be taken into account when analyzing the results of CIDNP experiments at low magnetic field. Moreover, such coherent polarization transfer can be efficiently exploited to polarize spins, which do not acquire CIDNP directly. Here we explain under what conditions such coherences can be generated, focusing on the key role of level anti-crossings in coherent polarization transfer, and provide experimental approaches to probing nuclear spin coherences and their time evolution. We illustrate the theoretical consideration of the outlined coherent spin phenomena in CIDNP by examples, obtained for the dipeptide tryptophan–tryptophan.

AB - Chemically induced dynamic nuclear polarization (CIDNP) has emerged as a highly informative method to study spin-dependent radical reactions by analyzing enhanced NMR (nuclear magnetic resonance) signals of their diamagnetic reaction products. In this way, one can probe the structure of elusive radical intermediates and determine their magnetic parameters. A careful examination of experimental CIDNP data at variable magnetic fields shows that formation of hyperpolarized molecules in a coherent state is a ubiquitous though rarely discussed phenomenon. The presence of nuclear spin coherences commonly leads to subsequent polarization transfer among coupled spins in the diamagnetic products of radical recombination reaction that must be taken into account when analyzing the results of CIDNP experiments at low magnetic field. Moreover, such coherent polarization transfer can be efficiently exploited to polarize spins, which do not acquire CIDNP directly. Here we explain under what conditions such coherences can be generated, focusing on the key role of level anti-crossings in coherent polarization transfer, and provide experimental approaches to probing nuclear spin coherences and their time evolution. We illustrate the theoretical consideration of the outlined coherent spin phenomena in CIDNP by examples, obtained for the dipeptide tryptophan–tryptophan.

UR - http://www.scopus.com/inward/record.url?scp=85108615528&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/9102aebe-59dd-3bb2-a090-64f5a494950a/

U2 - 10.1007/s00723-021-01348-9

DO - 10.1007/s00723-021-01348-9

M3 - Article

AN - SCOPUS:85108615528

VL - 53

SP - 595

EP - 613

JO - Applied Magnetic Resonance

JF - Applied Magnetic Resonance

SN - 0937-9347

IS - 3-5

ER -