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Issue 48, 2014
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The role of the glassy dynamics and thermal mixing in the dynamic nuclear polarization and relaxation mechanisms of pyruvic acid

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Abstract

The temperature dependence of 1H and 13C nuclear spin–lattice relaxation rate 1/T1 has been studied in the 1.6–4.2 K temperature range in pure pyruvic acid and in pyruvic acid containing trityl radicals at a concentration of 15 mM. The temperature dependence of 1/T1 is found to follow a quadratic power law for both nuclei in the two samples. Remarkably the same temperature dependence is displayed also by the electron spin–lattice relaxation rate 1/T1e in the sample containing radicals. These results are explained by considering the effect of the structural dynamics on the relaxation rates in pyruvic acid. Dynamic nuclear polarization experiments show that below 4 K the 13C build up rate scales with 1/T1e, in analogy to 13C 1/T1 and consistently with a thermal mixing scenario where all the electrons are collectively involved in the dynamic nuclear polarization process and the nuclear spin reservoir is in good thermal contact with the electron spin system.

Graphical abstract: The role of the glassy dynamics and thermal mixing in the dynamic nuclear polarization and relaxation mechanisms of pyruvic acid

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Publication details

The article was received on 14 Jun 2014, accepted on 27 Oct 2014 and first published on 10 Nov 2014


Article type: Paper
DOI: 10.1039/C4CP02636E
Author version available: Download Author version (PDF)
Citation: Phys. Chem. Chem. Phys., 2014,16, 27025-27036
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    The role of the glassy dynamics and thermal mixing in the dynamic nuclear polarization and relaxation mechanisms of pyruvic acid

    M. Filibian, S. Colombo Serra, M. Moscardini, A. Rosso, F. Tedoldi and P. Carretta, Phys. Chem. Chem. Phys., 2014, 16, 27025
    DOI: 10.1039/C4CP02636E

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