000204054 001__ 204054
000204054 005__ 20180913062909.0
000204054 0247_ $$2doi$$a10.1021/ja5088453
000204054 022__ $$a0002-7863
000204054 02470 $$2ISI$$a000344516600043
000204054 037__ $$aARTICLE
000204054 245__ $$aAmplifying Dynamic Nuclear Polarization of Frozen Solutions by Incorporating Dielectric Particles
000204054 260__ $$aWashington$$bAmerican Chemical Society$$c2014
000204054 269__ $$a2014
000204054 300__ $$a8
000204054 336__ $$aJournal Articles
000204054 520__ $$aThere is currently great interest in understanding the limits on NMR signal enhancements provided by dynamic nuclear polarization (DNP), and in particular if the theoretical maximum enhancements can be achieved. We show that over a 2-fold improvement in cross-effect DNP enhancements can be achieved in MAS experiments on frozen solutions by simply incorporating solid particles into the sample. At 9.4 T and similar to 105 K, enhancements up to epsilon(H) = 515 are obtained in this way, corresponding to 78% of the theoretical maximum. We also underline that degassing of the sample is important to achieve highest enhancements. We link the amplification effect to the dielectric properties of the solid material, which probably gives rise to scattering, diffraction, and amplification of the microwave field in the sample. This is substantiated by simulations of microwave propagation. A reduction in sample heating at a given microwave power also likely occurs due to reduced dielectric loss. Simulations indicate that the microwave field (and thus the DNP enhancement) is inhomogeneous in the sample, and we deduce that in these experiments between 5 and 10% of the solution actually yields the theoretical maximum signal enhancement of 658. The effect is demonstrated for a variety of particles added to both aqueous and organic biradical solutions.
000204054 700__ $$0249156$$aKubicki, Dominik J.$$g242993$$uUniv Lyon, UCB Lyon 1, Ctr RMN Tres Hauts Champs, Inst Sci Analyt,ENS Lyon,CNRS, F-69100 Villeurbanne, France
000204054 700__ $$0248569$$aRossini, Aaron J.$$g251584$$uUniv Lyon, UCB Lyon 1, Ctr RMN Tres Hauts Champs, Inst Sci Analyt,ENS Lyon,CNRS, F-69100 Villeurbanne, France
000204054 700__ $$aPurea, Armin$$uBruker Biospin GmbH, D-76287 Rheinstetten, Germany
000204054 700__ $$aZagdoun, Alexandre$$uUniv Lyon, UCB Lyon 1, Ctr RMN Tres Hauts Champs, Inst Sci Analyt,ENS Lyon,CNRS, F-69100 Villeurbanne, France
000204054 700__ $$aOuari, Olivier$$uAix Marseille Univ, CNRS, ICR, UMR 7273, F-13397 Marseille, France
000204054 700__ $$aTordo, Paul$$uAix Marseille Univ, CNRS, ICR, UMR 7273, F-13397 Marseille, France
000204054 700__ $$aEngelke, Frank$$uBruker Biospin GmbH, D-76287 Rheinstetten, Germany
000204054 700__ $$aLesage, Anne$$uUniv Lyon, UCB Lyon 1, Ctr RMN Tres Hauts Champs, Inst Sci Analyt,ENS Lyon,CNRS, F-69100 Villeurbanne, France
000204054 700__ $$0248253$$aEmsley, Lyndon$$g251248$$uUniv Lyon, UCB Lyon 1, Ctr RMN Tres Hauts Champs, Inst Sci Analyt,ENS Lyon,CNRS, F-69100 Villeurbanne, France
000204054 773__ $$j136$$k44$$q15711-15718$$tJournal Of The American Chemical Society
000204054 909C0 $$0252518$$pLRM$$xU12975
000204054 909CO $$ooai:infoscience.tind.io:204054$$pSB$$particle
000204054 917Z8 $$x221596
000204054 937__ $$aEPFL-ARTICLE-204054
000204054 973__ $$aEPFL$$rREVIEWED$$sPUBLISHED
000204054 980__ $$aARTICLE