Level anti-crossings in ParaHydrogen Induced Polarization experiments with Cs-symmetric molecules

Buljubasich, L.; Franzoni, María Belén; Spiess, Hans Wolfgang; Münnemann, Kerstin

doi:10.1016/j.jmr.2012.03.020

Cited by 70 publications

(102 citation statements)

References 24 publications

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“…The transformation of total spin magnetization into singlet order, and back again, is an important manipulation in the NMR of long-lived states [13,14,15,16,17,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44] and in parahydrogen-enhanced NMR [18,19,20,21,22,45,46,47,48,49].…”

Section: Magnetization To Singlet Ordermentioning

confidence: 99%

Symmetry constraints on spin dynamics: Application to hyperpolarized NMR

Levitt

2016

Journal of Magnetic Resonance

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Spin dynamical evolution is constrained by the symmetries of the spin Hamiltonians that generate the quantum dynamics. The consequences of symmetry-induced constraints are examined for some common hyperpolarized NMR experiments, including the excitation of singlet order in spin-pair systems, and the transfer of parahydrogen-induced hyperpolarized singlet order to magnetization in systems displaying chemical and magnetic equivalence.

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Section: Magnetization To Singlet Ordermentioning

confidence: 99%

Symmetry constraints on spin dynamics: Application to hyperpolarized NMR

Levitt

2016

Journal of Magnetic Resonance

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“…Previously, pronounced features in the CIDNP field dependence due to LACs were reported 24 and they have also been considered in PHIP. [25][26][27] However, polarization transfer kinetics was never studied in detail and nor was the coherent nature of the transfer efficiently exploited.…”

Section: Introductionmentioning

confidence: 99%

Exploiting level anti-crossings for efficient and selective transfer of hyperpolarization in coupled nuclear spin systems

Pravdivtsev

Yurkovskaya

Kaptein

et al. 2013

Phys. Chem. Chem. Phys.

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Spin hyperpolarization can be coherently transferred to other nuclei in field-cycling NMR experiments.At low magnetic fields spin polarization is redistributed in a strongly coupled network of spins.Polarization transfer is most efficient at fields where level anti-crossings (LACs) occur for the nuclear spin-states. A further condition is that field switching to the LAC positions is non-adiabatic in order to convert the starting population differences into spin coherences that cause time-dependent mixing of states. The power of this method has been demonstrated by studying transfer of photo-Chemically Induced Dynamic Nuclear Polarization (photo-CIDNP) in N-acetyl-tryptophan. We have investigated the magnetic field dependence and time dependence of coherent CIDNP transfer and directly assessed nuclear spin LACs by studying polarization transfer at specific field positions. The proposed approach based on LACs is not limited to CIDNP but is advantageous for enhancing NMR signals by spin order transfer from any type of hyper-polarized nuclei.

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“…More recent work has shown that chemically equivalent [4,[18][19][20] [8,10,19,20]. Specifically, the so-called "M2S" sequence, consisting of precisely spaced π pulses, can interconvert magnetization and singlet-state polarization.…”

mentioning

confidence: 99%

Composite and shaped pulses for efficient and robust pumping of disconnected eigenstates in magnetic resonance

Theis¹,

Feng²,

Wu³

et al. 2014

The Journal of Chemical Physics

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‡ These authors contributed equally.Long-lived (symmetry protected) hyperpolarized spin states offer important new opportunities (for example, in clinical MR imaging), but existing methods for producing these states are limited by either excess energy dissipation or high sensitivity to inhomogeneities. We extend recent work on continuouswave irradiation of nearly-equivalent spins (spin-lock induced crossing) by designing composite pulse and adiabatic shaped-pulse excitations which overcome the limitations. These composite and adiabatic pulses differ drastically from the traditional solutions in two-level systems. We also show this works in chemically equivalent spin pairs, which has the advantage of allowing for polarization transfer from and to remote spins. The approach is broadly applicable to systems where varying excitation strength induces an avoided crossing to a dark state, and thus to many other spectroscopic regimes.Hyperpolarization methods produce nuclear magnetization many orders of magnitude larger than what is available at thermal equilibrium, and are particularly promising in clinical and preclinical applications of magnetic resonance imaging [1][2][3]. However, a fundamental challenge is the nuclear spin-lattice relaxation time T 1 , which typically is too short in solution or tissue (tens of seconds for carbon-13) to monitor many meaningful biological processes. For this reason, symmetry-protected nuclear spin states (such as the singlet, which is a "dark state" with no dipole allowed transitions) have drawn considerable attention [4][5][6][7][8][9][10][11][12][13][14][15][16][17].The first demonstrations [6,7] used inequivalent spins to convert population from the normally accessible triplet stateinto the singlet, then strong spin locking or translation to a low field to preserve the singlet state. More recent work has shown that chemically equivalent [4,[18][19][20] [8,10,19,20]. Specifically, the so-called "M2S" sequence, consisting of precisely spaced π pulses, can interconvert magnetization and singlet-state polarization. It has become clear that multiple families of biologically compatible molecules exist that can bear protected singlet states with lifetimes of many minutes to hours, giving this approach transformative potential.However, serious obstacles remain to using such reagents in MRI. The most important challenge is that in clinical applications, allowable energy deposition is limited. Recently, DeVience et. al. [21,22] introduced a new approach for pumping singlet states in nearly-equivalent spins, called spin-lock induced crossing (SLIC), which drastically decreases power dissipation but is not robust to the inevitable rf or static field inhomogeneities in MRI. Here we extend their approach to the equivalent-spin case, and create an energy-efficient and robust method for population transfer using novel composite and shaped pulses. Composite pulses have been used for decades to improve robustness in magnetic resonance [23,24] and laser [25,26] applications, as have shaped pulses;...

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Level anti-crossings in ParaHydrogen Induced Polarization experiments with Cs-symmetric molecules

Cited by 70 publications

References 24 publications

Symmetry constraints on spin dynamics: Application to hyperpolarized NMR

Symmetry constraints on spin dynamics: Application to hyperpolarized NMR

Exploiting level anti-crossings for efficient and selective transfer of hyperpolarization in coupled nuclear spin systems

Composite and shaped pulses for efficient and robust pumping of disconnected eigenstates in magnetic resonance

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