Sensitivity Enhancement in Solid State 15N NMR by Indirect Detection with High-Speed Magic Angle Spinning

Ishii, Yoshitaka; Tycko, Robert

doi:10.1006/jmre.1999.1976

Cited by 248 publications

(360 citation statements)

References 36 publications

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“…Because of the limited population of the target 15 N species and a broad line width, the signal-to-noise ratio in the direct-detected 15 N CPMAS spectra was low even with 15 N enrichment. Thus, we used 1 H detected 15 N-1 H double CP for the adjustment of the Hartmann-Hahn condition 43,44 . The 1 H polarization was excited by a 1 H π/2 pulse of 3.5-µs width.…”

Section: Methodsmentioning

confidence: 99%

Chemical structures of hydrazine-treated graphene oxide and generation of aromatic nitrogen doping

et al. 2012

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Chemically modified graphene platelets, produced via graphene oxide, show great promise in a variety of applications due to their electrical, thermal, barrier and mechanical properties. understanding the chemical structures of chemically modified graphene platelets will aid in the understanding of their physical properties and facilitate development of chemically modified graphene platelet chemistry. Here we use 13 C and 15 n solid-state nuclear magnetic resonance spectroscopy and X-ray photoelectron spectroscopy to study the chemical structure of 15 nlabelled hydrazine-treated 13 C-labelled graphite oxide and unlabelled hydrazine-treated graphene oxide, respectively. These experiments suggest that hydrazine treatment of graphene oxide causes insertion of an aromatic n 2 moiety in a five-membered ring at the platelet edges and also restores graphitic networks on the basal planes. Furthermore, density-functional theory calculations support the formation of such n 2 structures at the edges and help to elucidate the influence of the aromatic n 2 moieties on the electronic structure of chemically modified graphene platelets.

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Section: Methodsmentioning

confidence: 99%

Chemical structures of hydrazine-treated graphene oxide and generation of aromatic nitrogen doping

et al. 2012

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“…The MAS frequency was 7 kHz, and the temperature was unregulated but remained within the range 98-101 K. In both cases, 16 transients were acquired for each of 128 increments in the t 1 dimension, and the DNP enhancement was approximately 17. In (c) and (d), we show one dimensional 13 C MAS spectra obtained with and without DNP, respectively, using SPC5 recoupling with a double quantum phase cycle; (e) and (f) are CP spectra with and without DNP. The apparent intensity differences between the spectra in (c) and (e) are due to recoupling dynamics at short excitation times [31].…”

Section: Discussionmentioning

confidence: 99%

“…These are based upon indirect detection of low γ nuclei during fast MAS [13,14], improved multiple pulse decoupling [15], or a combination of both [27]. Thermal mixing DNP is complementary to these methods, as the dynamics of electron nuclear polarization transfer do not involve any coherent manipulation of the nuclear spins.…”

Section: Dnp Mas Experiments At 9 Tmentioning

confidence: 99%

“…In all cases, the applicability of these methods to larger systems and those in low abundance is currently limited by the necessity to directly observe signals of low gyromagnetic ratio (γ) nuclei, such as 13 C, 15 N, and 31 P, whose spectra are well-resolved. The indirect detection of dilute spin spectra through the more sensitive 1 H spins has not yet become generally practical in the solid state, due to strong homonuclear couplings among the protons [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

“…The indirect detection of dilute spin spectra through the more sensitive 1 H spins has not yet become generally practical in the solid state, due to strong homonuclear couplings among the protons [13][14][15]. As a result, solid state NMR is less sensitive by two or three orders of magnitude per unit time than solution state NMR.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic nuclear polarization at 9 T using a novel 250 GHz gyrotron microwave source

Bajaj

Farrar

Hornstein

et al. 2011

Journal of Magnetic Resonance

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In this communication, we report enhancements of nuclear spin polarization by dynamic nuclear polarization (DNP) in static and spinning solids at a magnetic field strength of 9T (250 GHz for g = 2 electrons, 380 MHz for 1 H). In these experiments, 1 H enhancements of up to 170 ± 50 have been observed in 1-13 C-glycine dispersed in a 60:40 glycerol/water matrix at temperatures of 20 K; in addition, we have observed significant enhancements in 15 N spectra of unoriented pf1-bacteriophage. Finally, enhancements of ~17 have been obtained in two-dimensional 13 C-13 C chemical shift correlation spectra of the amino acid U-13 C, 15 N-proline during magic angle spinning (MAS), demonstrating the stability of the DNP experiment for sustained acquisition and for quantitative experiments incorporating dipolar recoupling. In all cases, we have exploited the thermal mixing DNP mechanism with the nitroxide radical 4-amino-TEMPO as the paramagnetic dopant. These are the highest frequency DNP experiments performed to date and indicate that significant signal enhancements can be realized using the thermal mixing mechanism even at elevated magnetic fields. In large measure, this is due to the high microwave power output of the 250 GHz gyrotron oscillator used in these experiments.

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Magic‐Angle Spinning Solid‐State Nuclear Magnetic Resonance: Application to Structural Biology

Goldbourt

2009

Encyclopedia of Analytical Chemistry

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The application of magic‐angle spinning (MAS) solid‐state NMR methods to large‐scale problems in structural biology has seen a significant progress in the last decade. Improved hardware, better sample preparation techniques, and new methodologies have resulted in the ability to solve the three‐dimensional structures of proteins, and to study their dynamic properties, making this method a viable and important tool for understanding the relation between biological processes and protein structure and function. One of the biggest advantages of MAS solid‐state NMR is in the ability to study structures, which are not easily accessible by traditional methods such as X‐ray crystallography and solution NMR. Hence, new classes of important proteins and biological complexes such as membrane proteins, amyloid fibrils and prions, metalloenzymes, and viruses, have all been characterized to various extents. It is expected that the role of MAS solid‐state NMR in structural biology will increase significantly as the number of dedicated research groups rises, and methodologies and hardware further improve.

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Sensitivity Enhancement in Solid State 15N NMR by Indirect Detection with High-Speed Magic Angle Spinning

Cited by 248 publications

References 36 publications

Chemical structures of hydrazine-treated graphene oxide and generation of aromatic nitrogen doping

Chemical structures of hydrazine-treated graphene oxide and generation of aromatic nitrogen doping

Dynamic nuclear polarization at 9 T using a novel 250 GHz gyrotron microwave source

Magic‐Angle Spinning Solid‐State Nuclear Magnetic Resonance: Application to Structural Biology

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