Document Detail

1H dynamic nuclear polarization in supercritical ethylene at 1.4 T.
MedLine Citation:
PMID:  10698666     Owner:  NLM     Status:  MEDLINE    
(1)H dynamic nuclear polarization (DNP) has been measured in supercritical ethylene in the pressure range 60-300 bar in an external field of 1.4 T. A single-cell sapphire tube was used as a high-pressure cell, and powdered 1,3-bisdiphenylene-2-phenyl allyl (BDPA) free radicals were added and distributed at the wall of the cell. At all pressures the dominant DNP mechanism was a positive Overhauser enhancement, caused by proton-electron contact interactions at the fluid/solid radical interface. The observed enhancements varied from 12 at 60 bar to 17 at 300 bar. Besides the Overhauser enhancement, small solid state and thermal mixing enhancements also were observed, indicating that part of the ethylene was adsorbed at the radical surface for a prolonged time. The impacts of the experimental conditions on the Overhauser enhancement factors are discussed, and enhancements of at least 40-60 are estimated when the EPR saturation factor and the leakage factor become maximal. These data indicate that DNP-enhanced NMR has the potential of extending the impact of NMR in research areas involving supercritical fluids.
R A Wind; S Bai; J Z Hu; M S Solum; P D Ellis; D M Grant; R J Pugmire; C M Taylor; C R Yonker
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of magnetic resonance (San Diego, Calif. : 1997)     Volume:  143     ISSN:  1090-7807     ISO Abbreviation:  J. Magn. Reson.     Publication Date:  2000 Mar 
Date Detail:
Created Date:  2000-05-10     Completed Date:  2000-05-10     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9707935     Medline TA:  J Magn Reson     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  233-9     Citation Subset:  IM    
Copyright Information:
Copyright 2000 Academic Press.
Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
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MeSH Terms
Ethylenes / chemistry*
Magnetic Resonance Spectroscopy / methods*
Reg. No./Substance:
0/Ethylenes; 74-85-1/ethylene

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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