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This content will become publicly available on November 15, 2018

Title: Optimal sample formulations for DNP SENS: The importance of radical-surface interactions

The efficacy of dynamic nuclear polarization (DNP) surface-enhanced NMR spectroscopy (SENS) is reviewed for alumina, silica, and ordered mesoporous carbon (OMC) materials, with vastly different surface areas, as a function of the biradical concentration. Importantly, our studies show that the use of a “one-size-fits-all” biradical concentration should be avoided when performing DNP SENS experiments and instead an optimal concentration should be selected as appropriate for the type of material studied as well as its surface area. In general, materials with greater surface areas require higher radical concentrations for best possible DNP performance. This result is explained with the use of a thermodynamic model wherein radical-surface interactions are expected to lead to an increase in the local concentration of the polarizing agent at the surface. We also show, using plane-wave density functional theory calculations, that weak radical-surface interactions are the cause of the poor performance of DNP SENS for carbonaceous materials.
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [1] ; ORCiD logo [2] ;  [2] ;  [2]
  1. Ames Lab., Ames, IA (United States)
  2. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)
Publication Date:
Report Number(s):
IS-J-9394
Journal ID: ISSN 1359-0294; PII: S1359029417300894
Grant/Contract Number:
EEC-0813570; AC02-07CH11358
Type:
Accepted Manuscript
Journal Name:
Current Opinion in Colloid & Interface Science
Additional Journal Information:
Journal Volume: 33; Journal Issue: C; Journal ID: ISSN 1359-0294
Publisher:
Elsevier
Research Org:
Ames Lab., Ames, IA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; dynamic nuclear polarization; solid-state NMR; surface-enhanced NMR; mesoporous materials; carbonaceous materials
OSTI Identifier:
1411961