<i>De novo</i> prediction of cross-effect efficiency for magic angle spinning dynamic nuclear polarization

Mentink-Vigier, Frédéric; Barra, Anne‐Laure; Tol, Johan van; Hediger, Sabine; Lee, Daniel; Paëpe, Gaël De

doi:10.1039/c8cp06819d

Cited by 35 publications

(52 citation statements)

References 77 publications

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“…Additionally, the MAS CE mechanism described in subsection 2.1 is only efficient when the multiple energy level crossings and anti-crossings occur within a time shorter than T1(Si) [74]. As an example for nitroxide biradicals, such as AMUPol, T1(Si) times are about 0.5 ms [83] and as a result, the efficiency of the DNP transfer increases up to a MAS frequency of ca. 2 kHz (see Figure 12a).…”

Section: Mas Frequencymentioning

confidence: 99%

Recent developments in MAS DNP-NMR of materials

Rankin

Trébosc

Pourpoint

et al. 2019

Solid State Nuclear Magnetic Resonance

125

137

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Solid-state NMR spectroscopy is a powerful technique for the characterization of the atomic-level structure and dynamics of materials. Nevertheless, the use of this technique is often limited by its lack of sensitivity, which can prevent the observation of surfaces, defects or insensitive isotopes. Dynamic Nuclear Polarization (DNP) has been shown to improve by one to three orders of magnitude the sensitivity of NMR experiments on materials under Magic-Angle Spinning (MAS), at static magnetic field B0 ≥ 5 T, conditions allowing for the acquisition of high-resolution spectra. The field of DNP-NMR spectroscopy of materials has undergone a rapid development in the last ten years, spurred notably by the availability of commercial DNP-NMR systems. We provide here an in-depth overview of MAS DNP-NMR studies of materials at high B0 field. After a historical perspective of DNP of materials, we describe the DNP transfers under MAS, the transport of polarization by spin diffusion and the various contributions to the overall sensitivity of DNP-NMR experiments. We discuss the design of tailored polarizing agents and the sample preparation in the case of materials. We present the DNP-NMR hardware and the influence of key experimental parameters, such as microwave power, magnetic field, temperature and MAS frequency. We give an overview of the isotopes, which have been detected by this technique, and the NMR methods, which have been combined with DNP. Finally, we show how MAS DNP-NMR has been applied to gain new insights into the structure of organic, hybrid and inorganic materials with applications in fields, such as health, energy, catalysis, optoelectronics etc.

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Section: Mas Frequencymentioning

confidence: 99%

Recent developments in MAS DNP-NMR of materials

Rankin

Trébosc

Pourpoint

et al. 2019

Solid State Nuclear Magnetic Resonance

125

137

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“…20,21 The downward eld dependence of the whole DNP process is also well reproduced by numerical simulations. [21][22][23][24] Several approaches have recently been developed to overcome this unfavorable eld dependence. One solution to achieve high enhancements at very high magnetic elds is to exploit the favorable eld dependence of Overhauser Effect (OE) DNP.…”

Section: Introductionmentioning

confidence: 99%

TinyPols: a family of water-soluble binitroxides tailored for dynamic nuclear polarization enhanced NMR spectroscopy at 18.8 and 21.1 T

et al. 2020

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“…(c,d) Steady-state nuclear polarization, P ∞ , relative to electronic equilibrium polarization as a function of distance (c) and electronic relaxation time (d) obtained from simulations (dots) and from the analytical expressions given in eqs 7 and 8 (lines). All calculations were done for a single electron spin S = 1/2 coupled to a single I = 1/2 nucleus with the gyromagnetic ratio of 17 O in a 9.4 T magnetic field at 100 K under 0.35 MHz microwave irradiation 40 on-resonance with the double-quantum transitions and assuming T 2e = T 1e .…”

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confidence: 99%

Enabling Natural Abundance ¹⁷O Solid-State NMR by Direct Polarization from Paramagnetic Metal Ions

Jardón-Álvarez

Reuveni

Harchol

et al. 2020

J. Phys. Chem. Lett.

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Dynamic nuclear polarization (DNP) significantly enhances the sensitivity of nuclear magnetic resonance (NMR), increasing its applications and the quality of NMR spectroscopy as a characterization tool for materials. Efficient spin diffusion among the nuclear spins is considered to be essential for spreading the hyperpolarization throughout the sample, enabling large DNP enhancements. This scenario mostly limits the polarization enhancement of low-sensitivity nuclei in inorganic materials to the surface sites when the polarization source is an exogenous radical. In metal-ion-based DNP, the polarization agents are distributed in the bulk sample and act as a source of both relaxation and polarization enhancement. We have found that as long as the polarization agent is the main source of relaxation, the enhancement does not depend on the distance between the nucleus and dopant. As a consequence, the requirement of efficient spin diffusion is lifted, and the entire sample can be directly polarized. We exploit this finding to measure high-quality NMR spectra of 17 O in the electrode material Li 4 Ti 5 O 12 doped with Fe(III) despite its low abundance and long relaxation time.

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De novo prediction of cross-effect efficiency for magic angle spinning dynamic nuclear polarization

Abstract: From the polarizing agent geometry and EPR properties to the prediction of magic angle spinning dynamic nuclear polarization efficiency.

Cited by 35 publications

References 77 publications

Recent developments in MAS DNP-NMR of materials

Recent developments in MAS DNP-NMR of materials

TinyPols: a family of water-soluble binitroxides tailored for dynamic nuclear polarization enhanced NMR spectroscopy at 18.8 and 21.1 T

Enabling Natural Abundance ¹⁷O Solid-State NMR by Direct Polarization from Paramagnetic Metal Ions

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De novo prediction of cross-effect efficiency for magic angle spinning dynamic nuclear polarization

Abstract: From the polarizing agent geometry and EPR properties to the prediction of magic angle spinning dynamic nuclear polarization efficiency.

Cited by 35 publications

References 77 publications

Recent developments in MAS DNP-NMR of materials

Recent developments in MAS DNP-NMR of materials

TinyPols: a family of water-soluble binitroxides tailored for dynamic nuclear polarization enhanced NMR spectroscopy at 18.8 and 21.1 T

Enabling Natural Abundance 17O Solid-State NMR by Direct Polarization from Paramagnetic Metal Ions

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Enabling Natural Abundance ¹⁷O Solid-State NMR by Direct Polarization from Paramagnetic Metal Ions