Theoretical Aspects of Dynamic Nuclear Polarization in the Solid State: The Influence of High Radical Concentrations on the Solid Effect and Cross Effect Mechanisms
Theoretical Aspects of Dynamic Nuclear Polarization in the Solid State: The Influence of High Radical Concentrations on the Solid Effect and Cross Effect Mechanisms
Hovav, Y., et al., Theoretical Aspects of Dynamic Nuclear Polarization in the Solid State: The Influence of High Radical Concentrations on the Solid Effect and Cross Effect Mechanisms. Appl. Magn. Reson., 2012. 43(1-2): p. 21-41.
Dynamic nuclear polarization (DNP) is used to enhance signals in NMR and MRI experiments. During these experiments microwave (MW) irradiation mediates transfer of spin polarization from unpaired electrons to their neighboring nuclei. Solid state DNP is typically applied to samples containing high concentrations (i.e. 10–40 mM) of stable radicals that are dissolved in glass forming solvents together with molecules of interest. Three DNP mechanisms can be responsible for enhancing the NMR signals: the solid effect (SE), the cross effect (CE), and thermal mixing (TM). Recently, numerical simulations were performed to describe the SE and CE mechanisms in model systems composed of several nuclei and one or two electrons. It was shown that the presence of core nuclei, close to DNP active electrons, can result in a decrease of the nuclear polarization, due to broadening of the double quantum (DQ) and zero quantum (ZQ) spectra. In this publication we consider samples with high radical concentrations, exhibiting broad inhomogeneous EPR line-shapes and slow electron cross-relaxation rates, where the TM mechanism is not the main source for the signal enhancements. In this case most of the electrons in the sample are not affected by the MW field applied at a discrete frequency. Numerical simulations are performed on spin systems composed of several electrons and nuclei in an effort to examine the role of the DNP inactive electrons. Here we show that these electrons also broaden the DQ and ZQ spectra, but that they hardly cause any loss to the DNP enhanced nuclear polarization due to their spin-lattice relaxation mechanism. Their presence can also prevent some of the polarization losses due to the core nuclei.
Quantitative cw Overhauser effect dynamic nuclear polarization for the analysis of local water dynamics
From The DNP-NMR Blog:
Quantitative cw Overhauser effect dynamic nuclear polarization for the analysis of local water dynamics
Franck, J.M., et al., Quantitative cw Overhauser effect dynamic nuclear polarization for the analysis of local water dynamics. Prog Nucl Magn Reson Spectrosc, 2013. 74(0): p. 33-56.
http://www.ncbi.nlm.nih.gov/pubmed/24083461
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11-21-2013 01:14 AM
Dynamic Nuclear Polarization Enhanced NMR in the Solid-State
From The DNP-NMR Blog:
Dynamic Nuclear Polarization Enhanced NMR in the Solid-State
Akbey, Ü., et al., Dynamic Nuclear Polarization Enhanced NMR in the Solid-State. 2013, Springer Berlin Heidelberg. p. 1-48.
http://dx.doi.org/10.1007/128_2013_436
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08-26-2013 08:46 PM
[NMR paper] Dynamic Nuclear Polarization Enhanced NMR in the Solid-State.
Dynamic Nuclear Polarization Enhanced NMR in the Solid-State.
Dynamic Nuclear Polarization Enhanced NMR in the Solid-State.
Top Curr Chem. 2013 Jul 7;
Authors: Akbey U, Franks WT, Linden A, Rydmark MO, Lange S, Oschkinat H
Abstract
Nuclear magnetic resonance (NMR) spectroscopy is one of the most commonly used spectroscopic techniques to obtain information on the structure and dynamics of biological and chemical materials. A variety of samples can be studied including solutions, crystalline solids, powders and hydrated protein...
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07-09-2013 02:47 PM
The interplay between the solid effect and the cross effect mechanisms in solid state 13C DNP at 95 GHz using trityl radicals
From The DNP-NMR Blog:
The interplay between the solid effect and the cross effect mechanisms in solid state 13C DNP at 95 GHz using trityl radicals
Banerjee, D., et al., The interplay between the solid effect and the cross effect mechanisms in solid state 13C DNP at 95 GHz using trityl radicals. J. Magn. Reson., 2013. 230(0): p. 212-219.
http://dx.doi.org/10.1016/j.jmr.2013.02.010
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05-07-2013 12:31 AM
High-Field (13)C Dynamic Nuclear Polarization with a Radical Mixture
From the The DNP-NMR Blog:
High-Field (13)C Dynamic Nuclear Polarization with a Radical Mixture
Michaelis, V.K., et al., High-Field (13)C Dynamic Nuclear Polarization with a Radical Mixture. J Am Chem Soc, 2013.
http://www.ncbi.nlm.nih.gov/pubmed/23373472
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04-15-2013 08:52 AM
Dual-band Selective Double Cross Polarization for Heteronuclear Polarization Transfer between Dilute Spins in Solid-State MAS NMR
Dual-band Selective Double Cross Polarization for Heteronuclear Polarization Transfer between Dilute Spins in Solid-State MAS NMR
Publication year: 2012
Source:Journal of Magnetic Resonance</br>
Zhengfeng Zhang, Yimin Miao, Xiaoli Liu, Jun Yang, Conggang Li, Feng Deng, Riqiang Fu</br>
A sinusoidal modulation scheme is described for selective heteronuclear polarization transfer between two dilute spins in double cross polarization magic-angle-spinning nuclear magnetic resonance spectroscopy. During the second N->C cross polarization, the 13C RF amplitude is...
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03-09-2012 09:16 AM
Dual-band Selective Double Cross Polarization for Heteronuclear Polarization Transfer between Dilute Spins in Solid-State MAS NMR
Dual-band Selective Double Cross Polarization for Heteronuclear Polarization Transfer between Dilute Spins in Solid-State MAS NMR
Publication year: 2012
Source: Journal of Magnetic Resonance, Available online 5 March 2012</br>
Zhengfeng*Zhang, Yimin*Miao, Xiaoli*Liu, Jun*Yang, Conggang*Li, ...</br>
A sinusoidal modulation scheme is described for selective heteronuclear polarization transfer between two dilute spins in double cross polarization magic-angle-spinning nuclear magnetic resonance spectroscopy. During the second N->C cross polarization, theC RF amplitude is modulated...
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03-06-2012 06:04 AM
Dynamic nuclear polarization experiments at 14.1 T for solid-state NMR.
Dynamic nuclear polarization experiments at 14.1 T for solid-state NMR.
Related Articles Dynamic nuclear polarization experiments at 14.1 T for solid-state NMR.
Phys Chem Chem Phys. 2010 Jun 14;12(22):5799-803
Authors: Matsuki Y, Takahashi H, Ueda K, Idehara T, Ogawa I, Toda M, Akutsu H, Fujiwara T
Instrumentation for high-field dynamic nuclear polarization (DNP) at 14.1 T was developed to enhance the nuclear polarization for NMR of solids. The gyrotron generated 394.5 GHz submillimeter (sub-mm) wave with a power of 40 W in the second harmonic...