Quantum‐rotor‐induced polarization

Meier, Benno

doi:10.1002/mrc.4725

Cited by 20 publications

(15 citation statements)

References 55 publications

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“…The inherent insensitivity arises due to the small population differences of the energy states that it probes. Dynamic nuclear polarization (DNP), quantum‐rotor induced polarisation, spin‐exchange optical pumping (SEOP) and para hydrogen induced polarization (PHIP) are four hyperpolarization methods that lead to improved population differences. Thus, these methods are extensively used for the analysis and detection of metabolites or pharmaceuticals, catalytic intermediates and for medical imaging purposes…”

Section: Introductionmentioning

confidence: 99%

Hyperpolarization of Pyridyl Fentalogues by Signal Amplification By Reversible Exchange (SABRE)

et al. 2019

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Fentanyl, also known as 'jackpot', is a synthetic opiate that is 50-100 times more potent than morphine. Clandestine laboratories produce analogues of fentanyl, known as fentalogues to circumvent legislation regarding its production. Three pyridyl fentalogues were synthesized and then hyperpolarized by signal amplification by reversible exchange (SABRE) to appraise the forensic potential of the technique. A maximum enhancement of -168-fold at 1.4 T was recorded for the ortho pyridyl 1 H nuclei. Studies of the activation parameters for the three fentalogues revealed that the ratio of ligand loss trans to hydride and hydride loss in the complex [Ir(IMes)(L) 3 (H) 2 ] + (IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazole-2-ylidene) ranged from 0.52 to 1.83. The fentalogue possessing the ratio closest to unity produced the largest enhancement subsequent to performing SABRE at earth's magnetic field. It was possible to hyperpolarize a pyridyl fentalogue selectively from a matrix that consisted largely of heroin (97 : 3 heroin:fentalogue) to validate the use of SABRE as a forensic tool.

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Section: Introductionmentioning

confidence: 99%

Hyperpolarization of Pyridyl Fentalogues by Signal Amplification By Reversible Exchange (SABRE)

et al. 2019

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“…Beyond 100 mT the increase with field persists, but is less than linear. T • 1,H decreases slightly as the temperature is increased from 4.2 to 20 K. As the temperature is increased further from 20 to 40 K T • 1,H decreases significantly, which may be associated with methyl-group-induced relaxation [24][25][26] .…”

Section: Linear Field-dependence Of Radical-induced Relaxationmentioning

confidence: 99%

Radical-induced Hetero-Nuclear Mixing and Low-field $^{13}$C Relaxation in Solid Pyruvic Acid

Kouřilová¹,

Jurkutat²,

Peat³

et al. 2022

Preprint

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In dynamic nuclear polarization, polarization is transferred from electron to nuclear spins at low temperatures. So far, it is not possible to predict the relaxation of hyperpolarized solids, and applications are developed largely by trial and error. Here, we study the low-field nuclear spin relaxation in pyruvic acid, doped with trityl. We find that, at low fields, the relaxation time constants for both 13 C and 1 H scale linearly with the applied field. We model the data using a thermodynamic approach, in which heat is transferred via triple-spin-flips involving two electron spins and one nuclear spin. The triple-spin-flip rate is calculated from first principles using a formalism developed by Wenckebach. The heat capacity of the Non-Zeeman reservoir is determined from the 1 H relaxation data at intermediate fields, which leads to a parameter-free, yet nearly quantitative description of the observed 1 H relaxation rates from 5 mT to 2 T. The observed 13 C relaxation is consistent with the formalism, provided that the direct energy exchange between the 1 H and 13 C reservoirs, and the diffusion barrier are accounted for at low and high fields, respectively. The formalism also describes the observed electron-mediated 1 H-13 C thermal mixing.

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“…Long-lived spin operators in rapidly rotating methyl groups are of great practical relevance, due to their connection to quantum rotor induced polarisation (QRIP) effects, for example [31][32][33][34][35][36][37]52,54,79,80 . Extensive discussions of long-lived spin operators in rotating methyl groups have been given in references 52-54.…”

Section: B Methyl Rotormentioning

confidence: 99%

Centralizer theory for long-lived spin states

Bengs

2021

The Journal of Chemical Physics

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Nuclear long-lived spin states represent spin density operator configurations that are exceptionally well protected against spin relaxation phenomena. Their long-lived character is exploited in a variety of Nuclear Magnetic Resonance (NMR) techniques. Despite growing importance of long-lived spin states in modern NMR strategies for their identification have changed little over the last decade. The standard approach heavily relies on a chain of group theoretical arguments. In this paper we present a more streamlined method for the calculation of such configurations. Instead of focusing on the symmetry properties of the relaxation superoperator, we focus on its corresponding relaxation algebra. This enables us to analyse long-lived spin states with Lie algebraic methods rather than group theoretical arguments. We show that the centralizer of the relaxation algebra forms a basis for the set of long-lived spin states. The characterisation of the centralizer on the other hand does not rely on any special symmetry arguments and its calculation is straightforward. We outline a basic algorithm and illustrate advantages by considering long-lived spin states for some spin-1/2 pairs and rapidly rotating methyl groups.

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Quantum‐rotor‐induced polarization

Cited by 20 publications

References 55 publications

Hyperpolarization of Pyridyl Fentalogues by Signal Amplification By Reversible Exchange (SABRE)

Hyperpolarization of Pyridyl Fentalogues by Signal Amplification By Reversible Exchange (SABRE)

Radical-induced Hetero-Nuclear Mixing and Low-field $^{13}$C Relaxation in Solid Pyruvic Acid

Centralizer theory for long-lived spin states

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