Frequency-chirped dynamic nuclear polarization with magic angle spinning using a frequency-agile gyrotron

Gao, Chukun; Alaniva, Nicholas; Saliba, Edward P.; Sesti, Erika L.; Judge, Patrick T.; Scott, Faith J.; Halbritter, Thomas; Sigurdsson, Snorri Th.; Barnes, Alexander B.

doi:10.1016/j.jmr.2019.106586

Cited by 23 publications

(18 citation statements)

References 43 publications

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“…Using this system, the output frequency can be rapidly modified (sweep rate of 20 MHz/μs over 670 MHz bandwidth) and the power output can be modulated, in tens of microseconds, from full power to complete shutdown . The chirp irradiation from this gyrotron was used for electron decoupling under DNP conditions leading to improved spectral resolution and improved DNP performance for assymetric biradicals . Pending further development, these second‐generation gyrotrons have potential to enable the long‐thought‐after high‐field pulsed DNP experiments.…”

Section: Sub‐thz Sourcesmentioning

confidence: 99%

Recent Advances in Magic Angle Spinning‐Dynamic Nuclear Polarization Methodology

Kaminker

2019

Israel Journal of Chemistry

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Dynamic nuclear polarization (DNP) is a method to boost the nuclear magnetic resonance (NMR) signal and thus alleviate the main limitation of NMR spectroscopy-its low sensitivity. One particularly successful methodology is the combination of DNP with magic angle spinning (MAS). MAS-DNP enables orders of magnitude signal enhancements in solid-state NMR experiments. The success of modern MAS-DNP stems from a combination of multiple developments in hardware, polarization agents design, sample preparation, theoretical understanding, and experimental methodology. Altogether these developments have allowed numerous breakthrough applications in biology and materials science. Despite its proven successes, ongoing research aims to further optimize hardware and polarization agent chemistry. Recent advances in MAS-DNP methodology that will allow unprecedented sensitivity in novel future applications are reviewed in this manuscript. Figure 3. (a) Schematic (left) and photograph (right) of the spinning module of nitrogen drive and bearing gas/helium-cooled design. (b-c) Schematics of the closed-loop helium-based DNP systems as developed (b) at the University of Grenoble Alpes and (c) at the Osaka University. Adapted from references 53, 48, 49 respectively.

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Section: Sub‐thz Sourcesmentioning

confidence: 99%

Recent Advances in Magic Angle Spinning‐Dynamic Nuclear Polarization Methodology

Kaminker

2019

Israel Journal of Chemistry

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“…At high fields ( 3.5 T), continuous-wave (CW) irradiation provided by gyrotrons is usually used, and the transfer is quite slow due to the low microwave power available at high frequencies. Recently, several groups have introduced schemes using broadband frequency-swept excitation (Hovav et al, 2014;Bornet et al, 2014;Kaminker and Han, 2018;Gao et al, 2019;Shimon and Kaminker, 2020). At lower fields and frequencies, quite an appreciable number of pulsed DNP variants are already available (Henstra et al, 1988;Tan et al, 2019a, c;Redrouthu and Mathies, 2022).…”

Section: Introductionmentioning

confidence: 99%

“…The method has potential with respect to investigating the influence of spin diffusion away from a paramagnetic centre (Wolfe, 1973;Stern et al, 2021;Tan et al, 2019b;Jain et al, 2021). On the other hand, we envisage the use of reverse DNP in electron-nuclear double-resonance (ENDOR) experiments of nuclei with substantial hyperfine couplings (Harmer, 2016;Rizzato et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Reverse dynamic nuclear polarisation for indirect detection of nuclear spins close to unpaired electrons

2022

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Abstract. Polarisation transfer schemes and indirect detection are central to magnetic resonance. Using the trityl radical OX063 and a pulse electron paramagnetic resonance spectrometer operating in the Q-band (35 GHz, 1.2 T), we show here that it is possible to use pulsed dynamic nuclear polarisation (DNP) to transfer polarisation from electrons to protons and back. The latter is achieved by first saturating the electrons and then simply using a reverse DNP step. A variable mixing time between DNP and reverse DNP allows us to investigate the decay of polarisation on protons in the vicinity of the electrons. We qualitatively investigate the influence of solvent deuteration, temperature, and electron concentration. We expect reverse DNP to be useful in the investigation of nuclear spin diffusion and envisage its use in electron–nuclear double-resonance (ENDOR) experiments.

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“…However, these experiments have been performed without MAS and at magnetic fields <3 T [15,27,29], primarily due to the difficulty of implementing MAS with the microwave resonators required to generate considerable electron nutation frequencies. Frequency-swept DNP at higher magnetic fields has also been shown to improve DNP performance [30,31], but has only recently been implemented with MAS [32,33]. MAS improves the sensitivity and resolution of solid-state NMR [34][35][36][37][38] by partially averaging anisotropic interactions of the magnetic resonance Hamiltonian, and is a crucial aspect of applying DNP to systems of interest.…”

Section: Introductionmentioning

confidence: 99%

“…Here we characterize the behavior of frequency-chirped DNP experiments performed with MAS, expanding on our recent work [32]. We optimize frequency chirps from a custom-built frequency-agile high-power gyrotron [39] to produce large gains in intensity beyond those obtained with CW DNP.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Frequency-Chirped Dynamic Nuclear Polarization in Rotating Solids

Judge

Sesti²,

Alaniva³

et al. 2020

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Continuous wave (CW) dynamic nuclear polarization (DNP) is used with magic angle spinning (MAS) to enhance the typically poor sensitivity of nuclear magnetic resonance (NMR) by orders of magnitude. In a recent publication we show that further enhancement is obtained by using a frequency-agile gyrotron to chirp incident microwave frequency through the electron resonance frequency during DNP transfer. Here we characterize the effect of chirped MAS DNP by investigating the sweep time, sweep width, center-frequency, and electron Rabi frequency of the chirps. We show the advantages of chirped DNP with a trityl nitroxide biradical, and a lack of improvement with chirped DNP using AMUPol, a nitroxide biradical. Frequency-chirped DNP on a model system of urea in a cryoprotecting matrix yields an enhancement of 142, 21% greater than that obtained with CW DNP. We then go beyond this model system and apply chirped DNP to intact human cells. In human Jurkat cells, frequency-chirped DNP improves enhancement by 24% over CW DNP. The characterization of the chirped DNP effect reveals instrument limitations on sweep time and sweep width, promising even greater increases in sensitivity with further technology development. These improvements in gyrotron technology, frequency-agile methods, and in cell applications are expected to play a significant role in the advancement of MAS DNP.<br>

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Frequency-chirped dynamic nuclear polarization with magic angle spinning using a frequency-agile gyrotron

Cited by 23 publications

References 43 publications

Recent Advances in Magic Angle Spinning‐Dynamic Nuclear Polarization Methodology

Recent Advances in Magic Angle Spinning‐Dynamic Nuclear Polarization Methodology

Reverse dynamic nuclear polarisation for indirect detection of nuclear spins close to unpaired electrons

Characterization of Frequency-Chirped Dynamic Nuclear Polarization in Rotating Solids

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