A field-sweep/field-lock system for superconducting magnets—Application to high-field EPR

Maly, Thorsten; Bryant, Jeff; Ruben, D. J.; Griffin, Robert G.

doi:10.1016/j.jmr.2006.09.012

Cited by 26 publications

(25 citation statements)

References 14 publications

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“…For accurate field measurements, the spectrometer was equipped with a field/frequency lock system. 52 EPR measurements for biradical 7 and 8 were performed on an X-band CW-EPR (9.8 GHz, 0.34 T) spectrometer at room (RT). Spectral simulations have been carried out using the EasySpin package.…”

Section: Methodsmentioning

confidence: 99%

“…9,51,54 The NMR magnet is equipped with a superconducting sweep coil that allows field sweeps over ±750 G. For accurate field measurements the spectrometer is equipped with a field/frequency lock system. 52 All experiments were performed at 90 K at a spinning frequency ω r / 2 π =5 kHz and 100 kHz TPPM 1 H decoupling. 55 The 1 H and 13 C field strengths used for cross-polarization were typically 50 kHz.…”

Section: Methodsmentioning

confidence: 99%

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Rigid Orthogonal Bis-TEMPO Biradicals with Improved Solubility for Dynamic Nuclear Polarization

Dane¹,

Corzilius²,

Rizzato

et al. 2012

J. Org. Chem.

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The synthesis and characterization of oxidized bis-thioketal-trispiro dinitroxide biradicals that orient the nitroxides in a rigid, approximately orthogonal geometry is reported. The biradicals show better performance as polarizing agents in dynamic nuclear polarization (DNP) NMR experiments as compared to biradicals lacking the constrained geometry. In addition, the biradicals display improved solubility in aqueous media due to the presence of polar sulfoxides. The results suggest that the orientation of the radicals is not dramatically affected by the oxidation state of the sulfur atoms in the biradical, and we conclude that a biradical polarizing agent containing a mixture of oxidation states can be used for improved solubility without a loss in performance.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Rigid Orthogonal Bis-TEMPO Biradicals with Improved Solubility for Dynamic Nuclear Polarization

Dane¹,

Corzilius²,

Rizzato

et al. 2012

J. Org. Chem.

Self Cite

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“…For accurate field measurements, the spectrometer is equipped with a field/frequency lock system. 61 …”

Section: Methodsmentioning

confidence: 99%

2H-DNP-enhanced 2H–13C solid-state NMR correlation spectroscopy

Maly

Andreas

Smith

et al. 2010

Phys. Chem. Chem. Phys.

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Perdeuteration of biological macromolecules for magic angle spinning solid-state NMR spectroscopy can yield high-resolution 2H–13C correlation spectra and the method is therefore of great interest for the structural biology community. Here we demonstrate that the combination of sample deuteration and dynamic nuclear polarization yields resolved 2H–13C correlation spectra with a signal enhancement of ε ≥ 700 compared to a spectrum recorded with microwaves off and otherwise identical conditions. To our knowledge, this is the first time that 2H-DNP has been employed to enhance MAS-NMR spectra of a biologically relevant system. The DNP process is studied using several polarizing agents and the technique is applied to obtain 2H–13C correlation spectra of U-[2H, 13C] proline.

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“…Furthermore, if the field profile of a polarizing agent needs to be recorded, the system should be equipped with a field-lock system. 125 In such a system, the NMR signal of a small liquid sample (e.g., water) is monitored, allowing the field determination to very high accuracy.…”

Section: Superconducting Magnetsmentioning

confidence: 99%

Dynamic nuclear polarization at high magnetic fields

Maly¹,

Debelouchina²,

Bajaj³

et al. 2008

The Journal of Chemical Physics

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774

847

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Dynamic nuclear polarization (DNP) is a method that permits NMR signal intensities of solids and liquids to be enhanced significantly, and is therefore potentially an important tool in structural and mechanistic studies of biologically relevant molecules. During a DNP experiment, the large polarization of an exogeneous or endogeneous unpaired electron is transferred to the nuclei of interest (I) by microwave (μw) irradiation of the sample. The maximum theoretical enhancement achievable is given by the gyromagnetic ratios (γ e /γ l ), being ∼660 for protons. In the early 1950s, the DNP phenomenon was demonstrated experimentally, and intensively investigated in the following four decades, primarily at low magnetic fields. This review focuses on recent developments in the field of DNP with a special emphasis on work done at high magnetic fields (≥5 T), the regime where contemporary NMR experiments are performed. After a brief historical survey, we present a review of the classical continuous wave (cw) DNP mechanisms-the Overhauser effect, the solid effect, the cross effect, and thermal mixing. A special section is devoted to the theory of coherent polarization transfer mechanisms, since they are potentially more efficient at high fields than classical polarization schemes. The implementation of DNP at high magnetic fields has required the development and improvement of new and existing instrumentation. Therefore, we also review some recent developments in μw and probe technology, followed by an overview of DNP applications in biological solids and liquids. Finally, we outline some possible areas for future developments.

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A field-sweep/field-lock system for superconducting magnets—Application to high-field EPR

Cited by 26 publications

References 14 publications

Rigid Orthogonal Bis-TEMPO Biradicals with Improved Solubility for Dynamic Nuclear Polarization

Rigid Orthogonal Bis-TEMPO Biradicals with Improved Solubility for Dynamic Nuclear Polarization

2H-DNP-enhanced 2H–13C solid-state NMR correlation spectroscopy

Dynamic nuclear polarization at high magnetic fields

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