A spectrometer for EPR, DNP, and multinuclear high-resolution NMR

Singel, David J.; Seidel, H.; Kendrick, R. D.; Yannoni, C. S.

doi:10.1016/0022-2364(89)90273-4

Cited by 26 publications

(68 citation statements)

References 17 publications

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“…In the late 1980s, Wind et al (110), Yannoni and colleagues (114), and Schaefer and colleagues (115) integrated DNP into MAS NMR experiments using 40-GHz klystrons corresponding to 1 H frequencies of 60 MHz. Because of the low magnetic fields (B 0 = 1.4 T), these investigations were focused on polymers and other materials that yield relatively simple spectra.…”

Section: Evolution and Instrumentationmentioning

confidence: 99%

Magic Angle Spinning NMR of Proteins: High-Frequency Dynamic Nuclear Polarization and ¹H Detection

Andreas²,

Griffin

2015

Annu. Rev. Biochem.

133

100

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Magic angle spinning (MAS) NMR studies of amyloid and membrane proteins and large macromolecular complexes are an important new approach to structural biology. However, the applicability of these experiments, which are based on (13)C- and (15)N-detected spectra, would be enhanced if the sensitivity were improved. Here we discuss two advances that address this problem: high-frequency dynamic nuclear polarization (DNP) and (1)H-detected MAS techniques. DNP is a sensitivity enhancement technique that transfers the high polarization of exogenous unpaired electrons to nuclear spins via microwave irradiation of electron-nuclear transitions. DNP boosts NMR signal intensities by factors of 10(2) to 10(3), thereby overcoming NMR's inherent low sensitivity. Alternatively, it permits structural investigations at the nanomolar scale. In addition, (1)H detection is feasible primarily because of the development of MAS rotors that spin at frequencies of 40 to 60 kHz or higher and the preparation of extensively (2)H-labeled proteins.

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Section: Evolution and Instrumentationmentioning

confidence: 99%

Magic Angle Spinning NMR of Proteins: High-Frequency Dynamic Nuclear Polarization and ¹H Detection

Andreas²,

Griffin

2015

Annu. Rev. Biochem.

133

100

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“…Subsequent to the discovery of the principle of DNP in metals and liquids in 1953 [12], three currently accepted DNP mechanisms in dielectric solids, namely solid effect (SE) [13,14], cross effect (CE) [15][16][17], and thermal mixing (TM) [18], were also established until mid-1980s. In the 1980s, DNP was combined with the magic-angle spinning (MAS) SSNMR, enabling studies on organic polymers and other materials at enhanced sensitivity [18][19][20]. However, its application has long been limited to use under low external field conditions (B 0 < 1.4 T), due to a lack of suitable high-frequency microwave sources for higher fields.…”

Section: Introductionmentioning

confidence: 99%

Helium-cooling and -spinning dynamic nuclear polarization for sensitivity-enhanced solid-state NMR at 14T and 30K

Matsuki

Ueda

Idehara

et al. 2012

Journal of Magnetic Resonance

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“…The receiving horn is followed by a short section (≈ 4 inches or 101 mm) of fundamental mode waveguide that extends to just above the NMR coil, as shown in Figure 3. At this waveguide flange, it is possible to connect either a broad-band antenna such a standard pyramidal scalar gain antenna or a resonant structure consistent with DNP measurements such as a Fabry Perot cavity [52, 53] or a scroll resonator [54]. …”

Section: Millimeter-wave Subsystemmentioning

confidence: 99%

Design and characterization of a W-band system for modulated DNP experiments

Guy

Zhu

Ramanathan

2015

Journal of Magnetic Resonance

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Magnetic-field and microwave-frequency modulated DNP experiments have been shown to yield improved enhancements over conventional DNP techniques, and even to shorten polarization build-up times. The resulting increase in signal-to-noise ratios can lead to significantly shorter acquisition times in signal-limited multi-dimensional NMR experiments and pave the way to the study of even smaller sample volumes. In this paper we describe the design and performance of a broadband system for microwave frequency-and amplitude-modulated DNP that has been engineered to minimize both microwave and thermal losses during operation at liquid helium temperatures. The system incorporates a flexible source that can generate arbitrary waveforms at 94 GHz with a bandwidth greater than 1 GHz, as well as a probe that efficiently transmits the millimeter waves from room temperature outside the magnet to a cryogenic environment inside the magnet. Using a thin-walled brass tube as an overmoded waveguide to transmit a hybrid HE11 mode, it is possible to limit the losses to 1 dB across a 2 GHz bandwidth. The loss is dominated by the presence of a quartz window used to isolate the waveguide pipe. This performance is comparable to systems with corrugated waveguide or quasi-optical components. The overall excitation bandwidth of the probe is seen to be primarily determined by the final antenna or resonator used to excite the sample and its coupling to the NMR RF coil. Understanding the instrumental limitations imposed on any modulation scheme is key to understanding the observed DNP results and potentially identifying the underlying mechanisms. We demonstrate the utility of our design with a set of triangular frequency-modulated DNP experiments.

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A spectrometer for EPR, DNP, and multinuclear high-resolution NMR

Cited by 26 publications

References 17 publications

Magic Angle Spinning NMR of Proteins: High-Frequency Dynamic Nuclear Polarization and ¹H Detection

Magic Angle Spinning NMR of Proteins: High-Frequency Dynamic Nuclear Polarization and ¹H Detection

Helium-cooling and -spinning dynamic nuclear polarization for sensitivity-enhanced solid-state NMR at 14T and 30K

Design and characterization of a W-band system for modulated DNP experiments

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A spectrometer for EPR, DNP, and multinuclear high-resolution NMR

Cited by 26 publications

References 17 publications

Magic Angle Spinning NMR of Proteins: High-Frequency Dynamic Nuclear Polarization and 1H Detection

Magic Angle Spinning NMR of Proteins: High-Frequency Dynamic Nuclear Polarization and 1H Detection

Helium-cooling and -spinning dynamic nuclear polarization for sensitivity-enhanced solid-state NMR at 14T and 30K

Design and characterization of a W-band system for modulated DNP experiments

Contact Info

Product

Resources

About

Magic Angle Spinning NMR of Proteins: High-Frequency Dynamic Nuclear Polarization and ¹H Detection

Magic Angle Spinning NMR of Proteins: High-Frequency Dynamic Nuclear Polarization and ¹H Detection