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Radical-induced hetero-nuclear mixing and low-field 13C relaxation in solid pyruvic acid

Kouřilová, Hana; Jurkutat, Michael; Peat, David; Kouřil, Karel; Khan, Alixander S.; Horsewill, Anthony J.; MacDonald, James F.; Owers-Bradley, John; Meier, Benno

Radical-induced hetero-nuclear mixing and low-field 13C relaxation in solid pyruvic acid Thumbnail


Hana Kouřilová

Michael Jurkutat

David Peat

Karel Kouřil

Alixander S. Khan

Anthony J. Horsewill

James F. MacDonald

John Owers-Bradley

Benno Meier


Radicals serve as a source of polarization in dynamic nuclear polarization, but may also act as polarization sink, in particular at low field. Additionally, if the couplings between the electron spins and different nuclear reservoirs are stronger than any of the reservoirs’ couplings to the lattice, radicals can mediate hetero-nuclear polarization transfer. Here, we report radical-enhanced 13C relaxation in pyruvic acid doped with trityl. Up to 40 K, we find a linear carbon T1 field dependence between 5 mT and 2 T. We model the dependence quantitatively, and find that the presence of trityl accelerates direct hetero-nuclear polarization transfer at low fields, while at higher fields 13C relaxation is diffusion limited. Measurements of hetero-nuclear polarization transfer up to 600 mT confirm the predicted radical-mediated proton–carbon mixing.

Journal Article Type Article
Acceptance Date Nov 9, 2022
Online Publication Date Nov 14, 2022
Publication Date Dec 14, 2022
Deposit Date Dec 22, 2022
Publicly Available Date Dec 22, 2022
Journal Physical Chemistry Chemical Physics
Print ISSN 1463-9076
Electronic ISSN 1463-9084
Peer Reviewed Peer Reviewed
Volume 24
Issue 46
Pages 28242-28249
Keywords Physical and Theoretical Chemistry, General Physics and Astronomy
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