Dynamic nuclear polarization of diamond. III. Paramagnetic electron relaxation times from enhanced 13C nuclear magnetic resonance signals

ABSTRACTThe 1H and 13C nuclear magnetic resonance (NMR) of thin diamond films deposited from naturally abundant (1.1 at.%) as well as 50% and 100% 13C-enriched CH4 heavily diluted in H2is described and discussed. Less than 0.6 at.% of hydrogen is found in the films which contain crystallites up to ∼15 μm across. The 1H NMR consists of a broad 50–65 kHz wide Gaussian line attributed to H atoms bonded to carbon and covering the crystallite surfaces. A narrow Lorentzian line was only occasionally observed and found not to be intrinsic to the diamonds. The 13C NMR demonstrates that >99.5% of the C atoms reside in a quaternary diamond-like configuration. The 13C spin-lattice relaxation times T1 are four orders of magnitude shorter than in natural diamond and believed to be due to 13C spin diffusion to paramagnetic centers, presumably carbon dangling bonds. Analysis of T1 indicates that within the 13C spin diffusion length of ∼0.05 μm these centers are uniformly distributed in the diamond crystallites, possibly concentrated on the internal surfaces of a relatively dense system of nanovoids.

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The effect of glassing solvent deuteration and Gd3+ doping on 13C DNP at 5 T

RSC Advances ◽

10.1039/c6ra02864k ◽

2016 ◽

Vol 6 (45) ◽

pp. 38855-38860 ◽

Cited By ~ 17

Author(s):

Andhika Kiswandhi ◽

Bimala Lama ◽

Peter Niedbalski ◽

Mudrekh Goderya ◽

Joanna Long ◽

...

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Dynamic Nuclear Polarization ◽

Sodium Acetate ◽

Nuclear Polarization ◽

Nuclear Magnetic

We report the influence of glassing solvent deuteration and Gd3+ doping on 13C dynamic nuclear polarization (DNP) nuclear magnetic resonance (NMR) performed on [1-13C] sodium acetate at B0 = 5 T and 1.2 K.

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Competing transfer pathways in direct and indirect dynamic nuclear polarization magic anglespinning nuclear magnetic resonance experiments on HIV-1 capsid assemblies: implications for sensitivity and resolution

Magnetic Resonance ◽

10.5194/mr-2-239-2021 ◽

2021 ◽

Vol 2 (1) ◽

pp. 239-249

Author(s):

Ivan V. Sergeyev ◽

Caitlin M. Quinn ◽

Jochem Struppe ◽

Angela M. Gronenborn ◽

Tatyana Polenova

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Dynamic Nuclear Polarization ◽

Nuclear Polarization ◽

Magic Angle Spinning ◽

Magic Angle ◽

Large Signal ◽

Experimental Conditions ◽

Hiv 1 ◽

Nuclear Magnetic

Abstract. Dynamic nuclear polarization (DNP)-enhanced magic angle spinning (MAS) nuclear magnetic resonance (NMR) of biological systems is a rapidly growing field. Large signal enhancements make the technique particularly attractive for signal-limited cases, such as studies of complex biological assemblies or at natural isotopic abundance. However, spectral resolution is considerably reduced compared to ambient-temperature non-DNP spectra. Herein, we report a systematic investigation into sensitivity and resolution of 1D and 2D 13C-detected DNP MAS NMR experiments on HIV-1 CA capsid protein tubular assemblies. We show that the magnitude and sign of signal enhancement as well as the homogeneous line width are strongly dependent on the biradical concentration, the dominant polarization transfer pathway, and the enhancement buildup time. Our findings provide guidance for optimal choice of sample preparation and experimental conditions in DNP experiments.

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